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  • Other Sources  (583)
  • Aerodynamics  (395)
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  • Seismicity
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  • 2015-2019  (316)
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  • 1
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    Unknown
    Seiscloud, a tool for density-based seismicity clustering and visualization (2020)
    Springer Netherlands
    Details
    Publication Date: 2023-06-09
    Description: Clustering algorithms can be applied to seismic catalogs to automatically classify earthquakes upon the similarity of their attributes, in order to extract information on seismicity processes and faulting patterns out of large seismic datasets. We describe here a Python open-source software for density-based clustering of seismicity named seiscloud, based on the pyrocko library for seismology. Seiscloud is a tool to dig data out of large local, regional, or global seismic catalogs and to automatically recognize seismicity clusters, characterized by similar features, such as epicentral or hypocentral locations, origin times, focal mechanisms, or moment tensors. Alternatively, the code can rely on user-provided distance matrices to identify clusters of events sharing indirect features, such as similar waveforms. The code can either process local seismic catalogs or download selected subsets of seismic catalogs, accessing different global seismicity catalog providers, perform the seismic clustering over different steps in a flexible, easily adaptable approach, and provide results in form of declustered seismic catalogs and a number of illustrative figures. Here, the algorithm usage is explained and discussed through an application to Northern Chile seismicity.
    Description: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ (4217)
    Keywords: ddc:551.22 ; Seismicity ; Clustering ; Location ; Moment tensor
    Language: English
    Type: doc-type:article
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  • 2
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    Seismicity in the Northern Rhine Area (1995–2018) (2020)
    Springer Netherlands
    Details
    Publication Date: 2023-06-09
    Description: Since the mid-1990s, the local seismic network of the University of Cologne has produced digital seismograms. The data all underwent a daily routine processing. For this study, we re-processed data of almost a quarter century of seismicity in the Northern Rhine Area (NRA), including the Lower Rhine Embayment (LRE) and the Eifel Mountain region (EMR). This effort included refined discrimination between tectonic earthquakes, mine-induced events, and quarry blasts. While routine processing comprised the determination of local magnitude ML, in the course of this study, source spectra-based estimates for moment magnitude MW for 1332 earthquakes were calculated. The resulting relation between ML and MW agrees well with the theory of an ML ∝ 1.5 MW dependency at magnitudes below 3. By applying Gutenberg-Richter relation, the b-value for ML was less (0.82) than MW (1.03). Fault plane solutions for 66 earthquakes confirm the previously published N118° E direction of maximum horizontal stress in the NRA. Comparison of the seismicity with recently published Global Positioning System–based deformation data of the crust shows that the largest seismic activity during the observation period in the LRE occurred in the region with the highest dilatation rates. The stress directions agree well with the trend of major faults, and declining seismicity from south to north correlates with decreasing strain rates. In the EMR, earthquakes concentrate at the fringes of the area with corresponding the largest uplift.
    Description: Projekt DEAL
    Keywords: ddc:551.22 ; Northern Rhine Area ; Lower Rhine Embayment ; Eifel ; Seismicity ; Moment magnitude ; Crustal deformation
    Language: English
    Type: doc-type:article
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  • 3
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    Journal of Geophysics - Zeitschrift für Geophysik 55 (2019)
    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148
    Details
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 31 Artikel zu Themengebieten der Geophysik, inklusive einer Ausgabe zur "Internationalen Magnetosphären Studie" und einer Ausgabe "Elektromagnetik", veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1984.
    Description: Inhaltsverzeichnis: Journal of Geophysics 55 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0011.pdf"〉Seismicity and dynamics of the Upper Rhinegraben〈/a〉〈br〉 (Bonjer, K.-P., Gelbke, C., Gilg, B., Rouland, D., Mayer-Rosa, D., Massinon, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0012.pdf"〉The crustal structure of the southern Rhinegraben from re-interpretation of seismic refraction data〈/a〉〈br〉 (Zuccu, J. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0013.pdf"〉On the identification of a transition zone in electrical conductivity between the lithosphere and asthenosphere: a plea for more precise phase data〈/a〉〈br〉(Cavaliere, T., Jones, A. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0014.pdf"〉The influence of geomagnetic variations on pipelines and an application for large-scale magnetotelluric depth sounding〈/a〉〈br〉 (Brasse, H., Junge, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0015.pdf"〉Some characteristics of the horizontal field variations around the geomagnetic jerk of 1970〈/a〉〈br〉 (Nevanlinna, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0016.pdf"〉Ground-based observations of a very intense substorm-related pulsation event〈/a〉〈br〉 (Lühr, H., Klöcker, N., Thürey, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0018.pdf"〉Dreidimensionale Seismik in der Exploration auf Kohlenwasserstoff-Lagerstätten〈/a〉〈br〉 (Dürschner, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0019.pdf"〉Long-term variations recorded by extensometers〈/a〉〈br〉 (Varga, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0020.pdf"〉Book reviews〈/a〉〈br〉 (Schneider, G., Jentzsch, G., Schick, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0021.pdf"〉Preface to the special issue ”Sixt Workshop on IMS observations in Northern Europe” held in Cumberland Logde, Windsor from 16-20 May 1983〈/a〉〈br〉 (Orr, D., Untiedt, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0022.pdf"〉Magnetospheric hydromagnetic waves: their eigenperiods, amplitudes and phase variations; a tutorial introduction〈/a〉〈br〉(Orr, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0023.pdf"〉ELF intensity levels at geostationary orbit and pulsating aurora〈/a〉〈br〉 (Ward, I. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0024.pdf"〉Ground observations of geomagnetic pulsations during a quiet magnetospheric interval correlated with satellite plasma measurements〈/a〉〈br〉 (Gough, H., Orr, D., Wedeken, U.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0025.pdf"〉Period, phase and resonant structure of a pulsation event seen by the ISEE 1 and 2 spacecraft on 2–3 April 1978〈/a〉〈br〉(Gardner, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0026.pdf"〉Pc5 pulsations and their possible source mechanisms: a case study〈/a〉〈br〉(Glaßmeier, K., Lester, M., Mier-Jedrzejowicz, W., Green, C., Rostoker, G., Orr, D., Wedeken, U., Junginger, H., Amata, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0027.pdf"〉Ground-satellite coordinated study of the April 5, 1979 events: flux variations of energetic particles and associated magnetic pulsations〈/a〉〈br〉(Wedeken, U., Inhester, B., Korth, A., Glaßmeier, K., Gendrin, R., Lanzerotti, L., Gough, H., Green, C., Amata, E., Pedersen, A., Rostoker, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0028.pdf"〉Ground-satellite coordinated study of the April 5, 1979 events: observation of O〈sup〉+〈/sup〉 cyclotron waves〈/a〉〈br〉(Inhester, B., Wedeken, U., Korth, A., Perraut, S., Stokholm, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0029.pdf"〉Preface to an “electromagnetic issue” initiated by a symposium of IAGA Working Group I-3 on August 23, 1983, during the IUGG General assembly in Hamburg〈/a〉〈br〉(Haak, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0030.pdf"〉Deep electromagnetic studies of the Baltic Shield〈/a〉〈br〉(Hjelt, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0031.pdf"〉Magnetometer array studies in Finland – determination of single station transfer functions〈/a〉〈br〉(Pajunpää, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0032.pdf"〉Models of geoelectrical anomalies in Czechoslovakia〈/a〉〈br〉(Červ, V., Pek, J., Praus, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0033.pdf"〉The electrical conductivity of the Andean crust in northern Chile and southern Bolivia as inferred from magnetotelluric measurements〈/a〉〈br〉(Schwarz, G., Haak, V., Martínez, E., Bannister, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0034.pdf"〉Electrical conductivity of the asthenosphere〈/a〉〈br〉(Vanyan, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0035.pdf"〉A high conductivity anomaly on the West African craton (Mali)〈/a〉〈br〉(Ritz, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0036.pdf"〉Search for a possible electromagnetic coupling between a transatlantic communication cable and the magma chamber in the mid-Atlantic ridge〈/a〉〈br〉(Meloni, A., Gregori, G., Lanzerotti, L., Medford, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0038.pdf"〉A new pulsed audiomagnetotelluric technique〈/a〉〈br〉(Schnegg, P.-A., Fischer, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0039.pdf"〉Preliminary results of MHD test registrations in northern Finland〈/a〉〈br〉(Heikka, J., Zhamaletdinov, A., Hjelt, S., Demidova, T., Velikhov, Y.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0040.pdf"〉Bimodal induction in non-uniform thin sheets: do the present algorithms work for regional studies?〈/a〉〈br〉(Mareschal, M., Vasseur, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0041.pdf"〉Solution of the stationary approximation for MT fields in the layered Earth with 3D and 2D inhomogeneities〈/a〉〈br〉(Hvoždara, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0042.pdf"〉Analogue-model magnetic field responses of an ocean channel, an island and a seamount in the Hainan Island region〈/a〉〈br〉(Hu, W. B., Dosso, H. W., Nienaber, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0055/LOG_0043.pdf"〉Conductivity modellling of the Earth using solar and lunar daily magnetic variations〈/a〉〈br〉(Winch, D. E.)〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DGG, DFG, SUB Göttingen
    Keywords: 550 ; Geophysik ; Africa ; Asthenosphere ; Aurora ; Baltic Shield ; China ; Czechoslovakia ; Earth’s Crust ; ELAS project ; Electrojets ; Electromagnetic Induction ; ELF waves ; Exploration Seismics ; Geomagnetic Induction Studies ; Geomagnetic Pulsations ; Geomagnetic Secular Variation ; Geomagnetic Variations ; Hydromagnetic Waves ; Ion Cyclotron Waves ; Magnetometer Arrays ; Magnetospheric Plasma ; Magnetotellurics ; MHD generator ; Pipelines ; Refraction Seismology ; Rhinegraben ; Satellite Observations ; Seismicity ; South America ; Transatlantic Cable ; FID-GEO-DE-7
    Language: German , English
    Type: anthology_digi
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  • 4
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    Unknown
    Journal of Geophysics - Zeitschrift für Geophysik 45 (2019)
    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148:45
    Details
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 44 Artikel zu Themengebieten der Seismologie, Erdmagnetismus und Gesteinsphysik veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1978.
    Description: Inhaltsverzeichnis: Journal of Geophysics 45 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0010.pdf"〉Magnetotelluric investigation of the lower crust and upper mantle Beneath Iceland〈/a〉〈br〉 (Beblo, M., Björnsson, A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0011.pdf"〉Damped and constrained least squares method with application to gravity interpretation〈/a〉〈br〉 (Vigneresse, J. L.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0012.pdf"〉Reappraisal of palaeomagnetism of the Colli Euganei and Monti Lessini Volcanics (Italy) 〈/a〉〈br〉 (Channell, J. E. T., De Zanche, V., Sedea, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0013.pdf"〉Reinterpretation of palaeomagnetism of the Colli Euganei and Monti Lessini (Italy) 〈/a〉〈br〉 (Soffel, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0014.pdf"〉Observations of the initial develpopment of an auroral and magnetic substorm at magnetic midnight〈/a〉〈br〉 (Untiedt, J., Pellinen, R., Küppers, F., Opgenoorth, H. J., Pelster, W. D., Baumjohann, W., Ranta, H., Kangas, J., Czechowsky, P., Heikkila, W. J.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0015.pdf"〉Ionospheric observation of gravity-waves associated with hurricane Eloise〈/a〉〈br〉 (Hung, R.J., Kuo, J. P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0016.pdf"〉On the annual wave of hemispheric geomagnetic activity〈/a〉〈br〉 (Damaske, D.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0017.pdf"〉Solar electron fluxes, increased geomagnetic activity and ionospheric absorption following selected flares〈/a〉〈br〉 (Märcz, F.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0018.pdf"〉The H amplitude of sudden commencements of magnetic storms at Sabhawala (Dehra Dun) 〈/a〉〈br〉 (Jain, A. R., Sastri, N. S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0019.pdf"〉Crustal structure of the Reykjanes Ridge at 63° N derived from seismic measurements〈/a〉〈br〉 (Snoek, M., Goldflam, S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0020.pdf"〉Book review〈/a〉〈br〉 (Strobach, K.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0021.pdf"〉Electron density in the South Atlantic anomaly region〈/a〉〈br〉 (Noor Sheikh, M., Rawer, K., Neske, E.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0023.pdf"〉Inversion of satellite magnetic anomaly data〈/a〉〈br〉 (Mayhew, M. A.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0026.pdf"〉The effect of earth structure on radial oscillations〈/a〉〈br〉 (Wang, C., Cleary, J. R., Anderssen, R. S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0027.pdf"〉Relationship between the seismic quality factor Q and the effective viscosity η〈/a〉〈br〉 (Meissner, R. O., Vetter, U. R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0028.pdf"〉The wave field associated with a fine structured moho in continents and oceans〈/a〉〈br〉 (Kosminskaya, I. P., Kapustian, N. K.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0029.pdf"〉Tidal triggering of earthquakes in the Swabian jura? 〈/a〉〈br〉 (Young, D., Zürn, W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0030.pdf"〉Theoretical investigations on acoustic remote sensing of ocean surface waves〈/a〉〈br〉 (Essen, H.-H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0031.pdf"〉A comparison of results of geothermal and magnetotelluric investigations in northwestern Germany〈/a〉〈br〉 (Knödel, K., Losecke, W., Wohlenberg, J.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0032.pdf"〉Effect of the coastline configuration of south Indian and Sri Lanka regions on the induced field at short period〈/a〉〈br〉 (Takeda, M., Maeda, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0034.pdf"〉Correction of graphs concerning the Chapman-Ferraro image method〈/a〉〈br〉 (Burkard, O. M., Rucker, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0036.pdf"〉On the difference between polarisation and coherence〈/a〉〈br〉 (Jones, A. G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0037.pdf"〉Palaeosecular variation studies of the Brunhes epoch in the volcanic province of the East-Eifel, Germany〈/a〉〈br〉 (Kohnen, H., Westkämper, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0038.pdf"〉Book review〈/a〉〈br〉 (Vees, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0039.pdf"〉Sixth annual meeting of the European Geophysical Society〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0040.pdf"〉Partial self-reversal of natural remanent magnetization of an historical lava flow of Mt. Etna (Sicily) 〈/a〉〈br〉 (Heller, F., Markert, H., Schmidbauer, E.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0044.pdf"〉Palaeomagnetic study of the tertiary volcanics of Sardinia〈/a〉〈br〉 (Edel, J.-B.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0046.pdf"〉Analysis of an eastward electrojet by means of upward continuation of ground-based magnetometer data〈/a〉〈br〉 (Mersmann, U., Baumjohann, W. Küppers, F., Lange, K.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0048.pdf"〉Non-linear rheology and return flow in the mantle〈/a〉〈br〉 (Jacoby, W. R., Ranalli, G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0051.pdf"〉Crustal and upper mantle structure beneath the Apennines region as inferred from the study of Rayleigh waves〈/a〉〈br〉 (Calcagnile, G., Panza, G. F.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0053.pdf"〉On the coastal effect on geoelectrical soundings〈/a〉〈br〉 (Mundry, E., Worzyk, P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0054.pdf"〉Observations of sPn from Swabian Alb earthquakes at the GRF array〈/a〉〈br〉 (Kind, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0055.pdf"〉Macroseismic intensity map of Austria for the Swabian Alb earthquake of September 3, 1978〈/a〉〈br〉 (Drimmel, J., Fiegweil, E., Lukeschitz, G.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0056.pdf"〉Das Schwerefeld im Bereich der Nordfriesischen Inseln und des benachbarten Festlands〈/a〉〈br〉 (Plaumann, S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0057.pdf"〉Probable relations between seismic anisotropy and a fine structure of the lithosphere〈/a〉〈br〉 (Meissner, R. O., Flüh, E. R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0058.pdf"〉Book reviews〈/a〉〈br〉 (Burkhardt, H.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0059.pdf"〉Reinterpretation of a deep-seismic-sounding profile on the Ukrainian shield〈/a〉〈br〉 (Jentsch, M.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0062.pdf"〉Extensions of the reflectivity method〈/a〉〈br〉 (Kind, R.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0063.pdf"〉Ray amplitudes of compressional, shear and converted seismic body waves in 3D laterally inhomogeneous media with curved interfaces〈/a〉〈br〉 (Pšenčík, I.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0064.pdf"〉Spectral analysis of Pc3 and Pc4 pulsations with regard to the dayside plasmapause position〈/a〉〈br〉 (Palandt, M.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0065.pdf"〉A theoretical investigation of the dipole- and unipole-resistivity methods for geoelectrical prospecting in Marine areas〈/a〉〈br〉 (Sebulke, J., Hildebrandt, W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0066.pdf"〉Paleomagnetism and rock magnetism of the Pliocene Rhyolite at San Vincenzo, Tuscany, Italy〈/a〉〈br〉 (Lowrie, W., Alvarez, W.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0067.pdf"〉On the presence of titanomagnetite in basalts〈/a〉〈br〉 (Radhakrishnamurty, C., Deutsch, E. R., Murthy, G. S.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0045/LOG_0068.pdf"〉Palaeomagnetism of permo-triassic red sandstones from the northern Calcareous Alps〈/a〉〈br〉 (Soffel, H.)〈/a〉〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DGG, DFG, SUB Göttingen
    Keywords: 550 ; Aurora ; Auroral Electrojet ; Austria ; Chapman-Ferraro Model ; Crustal Structure ; Earth Models ; Earthquakes ; Earth's Mantle ; Electrical Conductivity Anomalies ; Electromagnetic Induction ; Explosion Seismology ; Free Oscillation of Earth ; Geoelectrics ; Geomagnetic Activity ; Geomagnetic Pulsations ; Geothermics ; Germany ; Gravity Anomalies ; Hurricanes ; Iceland ; India ; Inverse Problems ; Ionosphere ; Ionosphäre ; Italy ; Lithosphere ; Magnetic Anomalies ; Magnetotellurics ; Moho ; Ocean Surface Waves ; Palaeomagnetism ; Polarisation Analysis ; Plasmapause ; Remote Sensing ; Rock Magnetism ; Seismic Anisotropy ; Seismicity ; Seismic Quality Factor Q ; Seismic Surface Waves ; Theoretical Seismograms ; USSR ; Viscosity of Earth ; FID-GEO-DE-7
    Language: German , English
    Type: anthology_digi
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    InSight's Reconstructed Aerothermal Environments (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: The InSight spacecraft was proposed to be a build-to-print copy of the Phoenix vehicle due to the knowledge that the lander payload would be similar and the trajectory would be similar. However, the InSight aerothermal analysts, based on tests performed in CO2 during the Mars Science Laboratory mission (MSL) and completion of Russian databases, considered radiative heat flux to the aftbody from the wake for the first time for a US Mars mission. The combined convective and radiative heat flux was used to determine if the as-flown Phoenix thermal protection system (TPS) design would be sufficient for InSight. All analyses showed that the design would be adequate. Once the InSight lander was successfully delivered to Mars on November 26, 2018, work began to reconstruct the atmosphere and trajectory in order to evaluate the aerothermal environments that were actually encountered by the spacecraft and to compare them to the design environments.The best estimated trajectory (BET) reconstructed for the InSight atmospheric entry fell between the two trajectories considered for the design, when looking at the velocity versus altitude values. The maximum heat rate design trajectory (MHR) flew at a higher velocity and the maximum heat load design trajectory (MHL) flew at a lower velocity than the BET. For TPS sizing, the MHL trajectory drove the design. Reconstruction has shown that the BET flew for a shorter time than either of the design environments, hence total heat load on the vehicle should have been less than used in design. Utilizing the BET, both DPLR and LAURA were first run to analyze the convective heating on the vehicle with no angle of attack. Both codes were run with axisymmetric, laminar flow in radiative equilibrium and vibrational non-equilibrium with a surface emissivity of 0.8. Eight species Mitcheltree chemistry was assumed with CO2, CO, N2, O2, NO, C, N, and O. Both codes agreed within 1% on the forebody and had the expected differences on the aftbody. The NEQAIR and HARA codes were used to analyze the radiative heating on the vehicle using full spherical ray-tracing. The codes agreed within 5% on most aftbody points of interest.The LAURA code was then used to evaluate the conditions at angle of attack at the peak heating and peak pressure times. Boundary layer properties were investigated to confirm that the flow over the forebody was laminar for the flight.Comparisons of the aerothermal heating determined for the reconstructed trajectory to the design trajectories showed that the as-flown conditions were less severe than design
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN70187 , International Planetary Probe Workshop (IPPW) 2019; Jul 08, 2019 - Jul 12, 2019; Oxford; United Kingdom
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    Lessons from Modeling Flexible Aircraft for Active Flutter Suppression (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: These slides describe a method and technology of modeling flexible aircraft for active control of structural dynamics. Objective: Generate models useful for the design and evaluation of control laws for active structural control and flutter suppression that are able to accurately predict body freedom flutter.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN66921 , Aerospace Control and Guidance Systems Committee (ACGSC) Meeting; Mar 27, 2019 - Mar 29, 2019; Santa Fe, NM; United States
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    Influence of Strain-Gage Balance Characteristics on the Precision Error of the Drag Coefficient (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Improvements and results of a new method are presented that computes a pre-test estimate of the precision error of the drag coefficient of a wind tunnel model. The error estimate is defined as the part of the drag coefficient's precision error that is primarily associated with the precision error of the angle of attack measurement and physical characteristics of the chosen strain-gage balance. The method indirectly describes the precision error of the angle of attack measurement by using an assumed balance gage output variation of one microV/V. The physical characteristics of the balance, on the other hand, are described by partial derivatives of the axial and normal forces with respect to the strain-gage outputs. These derivatives can directly be obtained from the data reduction matrix of the balance. The precision error estimate itself is calculated by applying a simple explicit equation that uses the model reference area, the dynamic pressure, the angle of attack, the coefficients of the linear terms of the data reduction matrix, and the electrical output variation of one microvolt per volt as input. Precision errors at constant angle of attack may be visualized as contour plots by plotting them, for example, versus the Mach number and the total pressure. Characteristics of NASA's MC60E balance are used in combination with the reference area of a generic wind tunnel model in order to demonstrate that error estimates are independent of both the balance load format and the units chosen for the description of balance loads, model reference area, and the dynamic pressure. Finally, experimental data from a wind tunnel test of the Ames Check Standard Model in the NASA Ames 11-foot Transonic Wind Tunnel illustrates the application of the method to real-world test data.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN63164 , AIAA SciTech 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Bowles-Tatnall Wake Vortex Encounter Hazard Metric (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Wake vortex spacing standards constrict the terminal area throughput and impose severe constraints on the overall capacity and efficiency of the National Airspace System. For more than two decades starting in the early 1990s, the National Aeronautics and Space Administration conducted extensive research on characterizing the formation and evolution of aircraft wakes. This multidisciplinary work included comprehensive field experiments (Pruis et al. 2016), flight tests (Vicroy et al. 1998), and wind tunnel tests (Rossow 1994; Chow et al. 1997). Parametric studies using large eddy simulations (Proctor 1998; Proctor et al. 2006) were conducted in order to develop fast-time models for the prediction of wake transport and decay (Ahmad et al. 2016). Substantial effort was spent on the formulation of acceptable vortex hazard metrics (Tatnall 1995; Hinton and Tatnall 1997). Several wake encounter severity metrics have been suggested in the past, which include the wake circulation strength, vortex-induced rolling moment coefficient (Clv), bank angle, and the roll control ratio (Tatnall 1995; Hinton and Tatnall 1997; Van der Geest 2012). The vortex-induced rolling moment coefficient introduced by Bowles and Tatnall (Tatnall 1995; Gloudemans et al. 2016) has been used extensively for risk and safety analysis of newly proposed air traffic management concepts and procedures. The original method of Bowles and Tatnall assumed a constant wing loading (the wing lift-curve slope, CL is constant), which resulted in an overestimation of the vortexinduced rolling moment coefficient. Bowles (2014) suggested a correction to the original method that provides more accurate values of Clv and which is also consistent with the underlying physics of the problem. The overestimation of Clv in the original method can be corrected by assuming an elliptical lift distribution. Figure 1.1 illustrates the correction in Clv achieved by the modified method.
    Keywords: Aerodynamics
    Type: NF1676L-33235 , NASA/TM-2019-220285 , L-21029
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    Time-varying Weights in Multi-Objective Optimal Control for Flexible Wing Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A multi-objective optimal control technique is modified to accommodate changing cost function weights and is used to control a flexible wing aircraft model. Variation of the weights is used to adjust the relative importance of each objective according to either a prescribed function of time or of the state. Several techniques for obtaining a practical approximation to the optimal control solution are presented, and stability of a specific weight structure with the optimal controller is demonstrated. Functionality of the multi-objective control design with weight variation is demonstrated in simulation of a flexible wing transport aircraft and is shown to improve performance over the fixed weight version both at a constant flight condition and across changing flight conditions.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN64647 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Multi-Objective Optimal Control of the 6-DoF Aeroservoelastic Common Research Model with Aspect Ratio 13.5 Wing (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A new 6-DoF aeroservoelastic (ASE) Common Research Model (CRM) provided by The Boeing Company with aspect ratio 13.5 and 17 control surfaces per wing is utilized to demonstrate combined tracking and optimal multi-objective control. The multi-objective controller is derived on the closed loop tracking controller, and utilizes state and gust estimates provided by an extended state observer. Various methods of model reduction useful for control and estimation are presented. A computationally efficient MATLAB/Simulink simulation is presented which includes actuator dynamics, rate and deflection saturation limits, and gust disturbance inputs. The platform is used to demonstrate excellent 6-DoF tracking control performance coupled with the multi-objective controller, which is shown to effectively reduce structural mode movement, wing root bending moment, and drag. State and gust estimation is also shown to perform well, even when derived and/or implemented with significantly fewer states than the original full-sized model.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN271828 , AIAA Science and Technology Forum and Exposition; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Surviving the Improbable: Upset Prevention and Recovery in Flight Control (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Slides for an invited presentation (as part of a series) at Santa Clara University, invited by prof. Mohammad Ayoubi. The slides are an overview and summary of past and current research projects in the field of envelope protection, upset prevention and stall recovery guidance, with the aim to avoid loss of control accidents and improve safety in air transportation. The overall aim of this presentation series is to inspire students and to show them possible opportunities that they can pursue for their later careers paths.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN52363 , Santa Clara University Invited Lecture Series; Santa Clara, CA; United States
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    Overflow Simulations of Unmanned Aircraft Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: National airspace, the management for access and operation of these vehicles is required. This management is being developed under the unmanned aircraft system traffic management system (UTM) program. To determine the aerodynamic characteristics of drones, wind tunnel experiments and computation fluid dynamic (CFD) analysis have been conducted. These experiments and analyses are undertaken to understand the flight capabilities of these vehicles in variable head and cross wind conditions. The results of these investigations will provide metrics for the safe operation of these vehicles in and around civil populations and in urban settings. The focus of this paper is to model a drone installed in a wind tunnel for varying pitch attitudes and rotor rpm settings. Specifically, the IRIS drone is modeled in the NASA-Ames 7x10 ft. W/T. The tunnel mounting hardware and the tunnel enclosure are modeled with the IRIS drone geometry. The rotors of the drone are modeled using two methodologies: a rotor disk model and individual blade representations. The results of the analysis are compared with available experimental data to validate the computational approach.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN64165 , AIAA Science and Technology Forum and Exposition 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Mid-Lift-to-Drag Ratio Rigid Vehicle 6-DOF EDL Performance Using Tunable Apollo Powered Guidance (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The Mid-Lift-to-Drag ratio Rigid Vehicle (MRV) is a candidate in the NASA multi-center effort to determine the most cost effective vehicle to deliver a large-mass payload to the surface of Mars for a human mission. Products of this effort include six-degree-of-freedom (6DoF) entry-to-descent trajectory performance studies for each candidate vehicle. These high fidelity analyses help determine the best guidance and control (G&C) strategies for a feasible, robust trajectory. This paper presents an analysis of the MRV's G&C design by applying common entry and descent associated uncertainties using a Fully Numerical Predictor-corrector Entry Guidance (FNPEG) and tunable Apollo powered descent guidance.
    Keywords: Aerodynamics
    Type: JSC-E-DAA-TN64439 , 2019 AAS/AIAA Space Flight Mechanics Meeting; Jan 13, 2019 - Jan 17, 2019; Ka''anapali, HI; United States
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    Additional Comparison of Iced Aerodynamic Measurements on a Swept Wing from Two Wind Tunnels (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Artificial ice shapes of various geometric fidelity were tested on a wing model based on the Common Research Model. Low Reynolds number test were conducted at Wichita State University's Walter H. Beech Memorial Wind utilizing an 8.9% scale model, and high Reynolds number tests were conducted at ONERA's F1 wind tunnel utilizing a 13.3% scale model. Several identical geometrically-scaled ice shapes were tested at both facilities, and the results were compared at overlapping Reynolds and Mach numbers. This was to ensure that the results and trends observed at low Reynolds number could be applied and continued to high, near-flight Reynolds number. The data from Wichita State University and ONERA F1 agreed well at matched Reynolds and Mach numbers. The lift and pitching moment curves agreed very well for most configurations. This confirmed results from previous tests with other ice shapes that indicated the data from the low Reynolds number tests could be used to understand ice-swept-wing aerodynamics at high Reynolds number. This allows ice aerodynamics testing to be performed at low Reynolds number facilities with much lower operating costs and generate results that are applicable to flight Reynolds number.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN67168 , International Conference on Icing of Aircraft, Engines and Structures; Jun 17, 2019 - Jun 21, 2019; Minneapolis, MN; United States
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    The Intermediate Wake of a Thin Flat Plate with a Circular Trailing Edge (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-11
    Description: The intermediate wakes of thin flat plates with circular trailing edges (TEs) are investigated here with direct numerical simulations (DNSs). The separating boundary layers are turbulent in all cases. The near wake in two thin-plate cases (IN & NS), with a focus on the vortex shedding process, was explored in a recent article. Intermittent shedding was observed in Case IN. Case NS, with half the TE diameter of Case IN, was an essentially non-shedding case. A third case (ST) with a sharp trailing edge was also investigated and found to exhibit an intermittent wake instability. The objectives of the present study are twofold. The first is to determine if the wake instability found in Case ST exists in Cases IN and NS as well. The second is to provide the distributions of the turbulent normal intensities and shear stress in the wake and to understand these distributions via the budget terms in the corresponding transport equations. The results show that both Cases IN & NS exhibit a wake instability in the intermediate wake region, that is similar to that found earlier in Case ST. We note that in Case IN, the presence of an intermediate-wake instability results in the co-existence of two different types of instability within a single wake. The distributions of the turbulent normal intensities and shear stress, and the budget terms for the streamwise intensity are included and discussed here. All the budget terms contribute appreciably to the overall budget in the transport equation for streamwise normal intensity.
    Keywords: Aerodynamics
    Type: NASA/TM-2019-220195 , ARC-E-DAA-TN67460
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    Shape and Angle-Of-Attack Measurements of Ram-Air Parachutes by Stereo Photogrammetry in the National Full-Scale Aerodynamics Complex (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: US Army MC-4/5 ram-air parachutes were tested in the 80- by 120-Ft test section of the National Full-Scale Aerodynamics Complex. Arrays of targets on the upper and lower surfaces of the central cell of the canopies were measured by stereo photogrammetry, and the target positions were used to estimate both the shape of the cell and angle of attack of the canopy. Forces and moments were measured by a six-axis load cell. Based on the photogrammetry and load-cell measurements, the relationships between lift, drag, and angle of attack were determined over a range of trailing-edge flap deflections, front riser lengths, and free-stream airspeeds. This paper describes the test, with an emphasis on the photogrammetry measurements, and presents a summary of results.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN68756 , 2019 AIAA Aviation and Aeronautics Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Indianapolis, IN; United States
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    ASPIRE Aerodynamic Models and Flight Performance (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: The Advanced Supersonic Parachute Inflation Research Experiments (ASPIRE) project waslaunched to develop the capability for testing supersonic parachutes at Mars-relevant conditions.Three initial parachute tests, targeted as a risk-reduction activity for NASA's upcomingMars2020 mission, successfully tested two candidate parachute designs and provided valuabledata on parachute inflation, forces, and aerodynamic behavior. Design of the flight tests dependedon flight mechanics simulations which in turn required aerodynamic models for the payload, andthe parachute. Computational Fluid Dynamics (CFD) was used to generate these models preflightand are compared against the flight data after the tests. For the payload, the reconstructedaerodynamic behavior is close to the pre-flight predictions, but the uncertainties in thereconstructed data are high due to the low dynamic pressures and accelerations during the flightperiod of comparison. For the parachute, the predicted time to inflation agrees well with the preflightmodel; the peak aerodynamic force and the steady state drag on the parachute are withinthe bounds of the pre-flight models, even as the models over-predict the parachute drag atsupersonic Mach numbers. Notably, the flight data does not show the transonic drag decreasepredicted by the pre-flight model. The ASPIRE flight tests provide previously unavailablevaluable data on the performance of a large full-scale parachute behind a slender leading bodyat Mars-relevant Mach number, dynamic pressure and parachute loads. This data is used topropose a new model for the parachute drag behind slender bodies to aid future experiments.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN68662 , AIAA Aviation Forum 2019; May 17, 2019 - May 21, 2019; Dallas, TX; United States
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    Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-31
    Description: Objectives: Reliable evaluation of mass flow rates through permeable boundaries - Estimate and control discretization error- Consider both computational domain outflow and inflow- Applicable to simulating propulsion-system effects, as well as secondary flow paths - Explore feasibility of handling more general outputs at domain boundaries. Design optimization subject to mass-flow-rate constraints - Improve aerodynamic performance and reduce noise due to sonic boom - Control discretization error in design space to improve confidence in final designs.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN69972 , AIAA Aviation and Aeronautics Forum (Aviation 2019); Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Further Development of the NASA X-57 Maxwell Mission Planning Tool for Mods II, III, and IV (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The experimental, fully electric X-57 Maxwell is designed to enable lower energy con-sumption at cruise compare to a fuel burning baseline. This is to be achieved using a sumof subsystem benefits incorporated in the electric, airframe, and propulsion systems. AMission Planning Tool captures the three stages of X-57 development in order to assess thedesign of each subsystem in the context of the whole aircraft. The Mission Planning Toolfor the fully electric X-57 Maxwell captures the aerodynamics, propulsion, heat transfer,and power system of the aircraft with trajectory optimization capabilities. It is able tomodel these subsystems through all phases of flight, from taxi to landing. Through thismultidisciplinary approach, we are able to predict the benefit of each subsystem and theeffect of key design assumptions and how the aircraft will react if they are not met or ex-ceeded. As the aircraft progresses and systems are tested, we can use the Mission PlanningTool to continue to predict performance. This paper details the continued development ofthe X-57 Mission Planning Tool and demonstrates its capabilities.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN71098 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    MRAC with Time-Varying Reference Model from Convex Combination (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-13
    Description: An extension of model reference adaptive control is presented that accommodates use of a time-varying reference model. Specifically, the reference model is taken to be a time-varying convex combination of two linear, time-invariant models. The design is intended to act as a way to smoothly transition between two different reference models without resorting to a scheduled switch. It also provides the ability to use an interpolated reference model when the plant is operating between design points. The time variation of the combination must satisfy some requirements to ensure stability but is otherwise user choice. Subject to these requirements, bounded tracking error behavior is demonstrated via Lyapunov stability analysis for the single-input, single-output, output feedback case. Tracking error convergence is asymptotic when time variation ceases. The proposed design is demonstrated in simulation of a numerical model.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN66631 , American Control Conference; Jul 10, 2019 - Jul 12, 2019; Philadelphia, PA; United States
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    NASA Armstrong Flight Research Center Dynamics and Controls (530) (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-30
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN74004
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    Large-Scale Boundary Layer Ingesting Propulsor Research (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-04
    Description: NASAs Advanced Air Transport Technology (AATT) project is investigating boundary layer ingesting (BLI) propulsors for advanced subsonic commercial vehicle concepts to enable the reduction of fuel burn. A multidisciplinary team of researchers from NASA, United Technologies Research Center (UTRC), Virginia Polytechnic University, and the Air Force Arnold Engineering Development Complex developed and tested an embedded BLI inlet and distortion-tolerant fan (BLI2DTF) system in the NASA Glenn Research Center (GRC) 8- foot by 6-foot (8x6) transonic wind tunnel. The test demonstrated the component performance goals necessary for an overall fuel burn reduction of 3 to 5 percent on a large hybrid wing body (HWB) aircraft. Special test equipment, including a raised floor with flow effectors and a bleed system, was developed for use in the 8x6 to produce the appropriate incoming boundary layer representative of an HWB application. Detailed measurements were made to determine the inlet total pressure loss and distortion, fan stage efficiency, and aeromechanic performance including blade vibration stress and displacement response. Results from this test were used as input to a vehicle-level system study performed by the AATT project to assess the impact of BLI on an alternative advanced concept aircraft referred to as the NASA D8 (ND8), which is somewhat similar to the HWB in its integration of the propulsor. This paper will provide an overview of the project timeline, special test equipment needed in the wind tunnel to develop the appropriate incoming boundary layer, and the difficulties in designing a propulsor for the test. The paper will conclude with some representative aerodynamic and aeromechanic data from the test itself and conclude with how this data was used in the ND8 system study.
    Keywords: Aerodynamics
    Type: ISABE-2019-24264 , GRC-E-DAA-TN72111 , International Society for Air Breathing Engines (ISABE) Conference; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    FUN3D Manual: 13.6 (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-30
    Description: This manual describes the installation and execution of FUN3D version 13.6, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
    Keywords: Aerodynamics
    Type: NF1676L-34707 , NASA/TM-2019-220416
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    Large-Scale Boundary Layer Ingesting Propulsor Research (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-29
    Description: _NASA's Advanced Air Transport Technology (AATT) project is investigating boundary layer ingesting (BLI) propulsors for advanced subsonic commercial vehicle concepts to enable the reduction of fuel burn. A multidisciplinary team of researchers from NASA, United Technologies Research Center (UTRC), Virginia Polytechnic University, and the Air Force Arnold Engineering Development Complex developed and tested an embedded BLI inlet and distortion-tolerant fan (BLI2DTF) system in the NASA Glenn Research Center (GRC) 8-foot by 6-foot (8x6) transonic wind tunnel. The test demonstrated the component performance goals necessary for an overall fuel burn reduction of 3 to 5 percent on a large hybrid wing body (HWB) aircraft. Special test equipment, including a raised floor with flow effectors and a bleed system, was developed for use in the 8x6 to produce the appropriate incoming boundary layer representative of an HWB application. Detailed measurements were made to determine the inlet total pressure loss and distortion, fan stage efficiency, and aeromechanic performance including blade vibration stress and displacement response. Results from this test were used as input to a vehicle-level system study performed by the AATT project to assess the impact of BLI on an alternative advanced concept aircraft referred to as the NASA D8 (ND8), which is somewhat similar to the HWB in its integration of the propulsor. This paper will provide an overview of the project timeline, special test equipment needed in the wind tunnel to develop the appropriate incoming boundary layer, and the difficulties in designing a propulsor for the test. The paper will conclude with some representative aerodynamic and aeromechanic data from the test itself and conclude with how this data was used in the ND8 system study.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN73213 , International Society for Air Breathing Engines (ISABE) Conference; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    Micro-scale Artificial Weave Generation Capabilities for Thermal Protection System Material Modeling (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-22
    Description: Thermal Protection System (TPS) modeling requires accurate representation and prediction of the thermomechanical behavior of ablative materials. State-of-the-art TPS materials such as Phenolic Impregnated Carbon Ablator (PICA) have a proven flight record and demonstrate exceptional capabilities for handling extreme aerothermal heating conditions. The constant push for lightweight materials that are flexible in their design and performance, and hence allow for a wide range of mission profiles, has led NASA over the past years to develop its Heatshield for Extreme Entry Environment Technology (HEEET). HEEET is based primarily on a dual layer woven carbon fiber architecture and the technology has successfully been tested in arc-jet facilities. These recent developments have sparked interest in the accurate micro-scale modeling of composite weave architectures, to predict the structural response of macro-scale heatshields upon atmospheric entry. This effort can be extended to incorporate in-depth failure mechanics analyses as a result of local thermal gradients or high-velocity particle impact.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73345 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    Effect of Out-Gassing on the Onset of Hypersonic Boundary Layer Transition (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: Prediction and control of the onset of transition and the associated variation in aerothermodynamic parameters in high-speed flows is key to optimize the performance and design of Thermal Protection Systems (TPS) of next-generation aerospace vehicles [1]. Boundary Layer Transition (BLT) characteristics can influence the surface heating budget determining the TPS thickness and consequently its weight penalty. Ablative heatshields are designed to alleviate the high heat flux at the surface through pyrolysis of their polymeric matrix and subsequent fiber ablation [2]. Pyrolysis leads to out-gassing and non-uniform ablation lead to surface roughness, both of which are known to influence the transition process. An ablator impacts BLT through three main routes: gas injecting into the boundary layer from the wall, changing the surface heat transfer due to wall-flow chemical reactions, and modifying surface roughness [3]. In preparation to Mars 2020 mission post-flight analysis, the predictive transition capability has been initiated toward hard-coupling porous material response analysis and aerothermal environment calculation.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73347 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    Progress Towards Modeling the Ablation Response of NuSil-Coated PICA (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: The Mars Science Laboratory (MSL) Entry, Descent and Landing Instrumentation (MEDLI) collected in-flight data largely used by the ablation community to verify and validate physics-based models for the response of the Phenolic Impregnated Carbon Ablator (PICA) material [1-4]. MEDLI data were recently used to guide the development of NASAs high-fidelity material response models for PICA, implemented in the Porous material Analysis Toolbox based on OpenFOAM (PATO) software [5-6]. A follow-up instrumentation suite, MEDLI2, is planned for the upcoming Mars 2020 mission [7] after the large scientific impact of MEDLI. Recent analyses performed as part of MEDLI2 development draw the attention to significant effects of a protective coating to the aerothermal response of PICA. NuSil, a silicone-based overcoat sprayed onto the MSL heatshield as contamination control, is currently neglected in PICA ablation models. To mitigate the spread of phenolic dust from PICA, NuSil was applied to the entire MSL heatshield, including the MEDLI plugs. NuSil is a space grade designation of the siloxane copolymer, primarily used to protect against atomic oxygen erosion in the Low Earth Orbit environment. Ground testing of PICA-NuSil (PICA-N) models all exhibited surface temperature jumps of the order of 200 K due to oxide scale formation and subsequent NuSil burn-off. It is therefore critical to include a model for the aerothermal response of the coating in ongoing code development and validation efforts.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73344 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    Verification of a Motion Cueing Strategy for Stall Recovery Training in a Commercial Transport Simulator (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper verifies a motion cueing strategy for improved pilot stall recovery training in commercial transport simulators. Eight airline transport pilots flew a high-altitude stall recovery task in the NASA B747 level-D-certified full flight simulator under three different motion configurations: no motion, baseline motion, and enhanced motion. For each motion condition, pilots performed the task with both baseline aircraft dynamics and aircraft dynamics enhanced with lateral-directional characteristics of the airplane at angle of attack approaching stall. Motion configuration significantly affected: 1) pilot opinions on the helpfulness of motion in performing the task, 2) the maximum roll angle in the stall maneuver, 3) the minimum load factor in the recovery, 4) the number of secondary stick shakers in the stall recovery, and 5) the maximum airspeed in the recovery. The two different aircraft dynamics significantly affected: 1) pilot opinions on the noticeability of the banking roll off near the stall and 2) the maximum roll angle in the stall maneuver. These results indicate that the relatively minor enhancements to the motion logic of heritage commercial transport simulators presented here can significantly improve pilot performance in simulated stall recoveries, and potentially improve stall recovery training.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN65276 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Flight Control Research at NASA Ames (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An overview of the flight control work in the Intelligent Systems Division at NASA Ames is presented. The highlight focuses on efforts surrounding performance-adaptive aeroelastic wing shaping for aircraft with flexible wings. Topics covered include aeroservoelastic modeling capabilities, online drag-optimizing control designs, gust and maneuver load alleviation techniques, and related wind tunnel demonstrations.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN67091 , Aerospace Control and Guidance Systems Committee Meeting; Mar 27, 2019 - Mar 29, 2019; Santa Fe, NM; United States
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    Evaluating the Aerodynamic Impact of Circumferentially Grooved Fan Casing Treatments with Integrated Acoustic Liners on a Turbofan Rotor (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA is investigating the potential of integrating acoustic liners into fan cases to reduce fan noise, while maintaining the fans aerodynamic performance. An experiment was conducted to quantify the aerodynamic impact of circumferentially grooved fan cases with integrated acoustic liners on a 1.5 pressure ratio turbofan rotor. In order to improve the ability to measure small performance changes, fan performance calculations were updated to include real gas effects including the effect of humidity. For all fan cases tested, the measured difference in fan isentropic efficiency was found to be less than the measurement repeatability for a torque-based efficiency calculation (approx. = 0.2%), however, an unintended tip clearance difference between configurations makes it difficult to determine if circumferentially grooved fan cases degraded fan performance. Fan exit turbulence measurements showed a 1.5% reduction in total turbulence intensity between hardwall and circumferentially grooved fan cases in the tip vortex region, which is attributed to a disruption in the formation of the tip leakage vortex. This decrease in fan exit turbulence could potentially lead to a 1-2dB reduction in broadband rotor-stator interaction noise. Reduced aerodynamic performance losses associated with over-the-rotor liners could enable further fan noise reduction.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN62158 , ASME Turbo Expo 2019 Turbomachinery Technical Conference & Exposition; Jun 17, 2019 - Jun 21, 2019; Phoenix, AZ; United States
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    CPAS Main Parachute Cluster Asymmetry: A Second Look (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: JSC-E-DAA-TN69878-2 , AIAA AVIATION Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Revisit of Load Asymmetry Observed During Orion Main Parachute Inflation (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aircraft Stability and Control
    Type: JSC-E-DAA-TN69878-1 , AIAA AVIATION Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Correlation of Full-Scale Isolated Proprotor Performance and Loads (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A full-scale isolated proprotor test is currently being conducted in the USAF National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames. The test article is a 3-bladed research rotor derived from the right-hand rotor of the AW609; this rotor was manufactured by Bell Helicopter under contract to NASA. In this paper, this research rotor is referred to as "699". The test, nearly completed, is an integral part of the initial checkout test of the newly developed Tiltrotor Test Rig (TTR), whose purpose is to test advanced, full-scale proprotors in the NFAC. Figure 1 shows the TTR/699 installed in the 40- by 80-Foot test section. The TTR rotor axis is horizontal and the rig rotates in yaw on the wind tunnel turntable for conversion (transition) and helicopter mode testing. To date, a substantial amount of wind tunnel test data has already been acquired. The completed operational conditions include hover, airplane mode (cruise, wind tunnel airspeed V=61 to 267 knots), and the helicopter and conversion conditions (with a comprehensive sweep of the TTR yaw angle ranging, to date, from 90-deg yaw helicopter mode to 30-deg yaw conversion mode, at varying airspeeds). This 699 proprotor performance and loads correlation study uses these newly acquired wind tunnel test data. This paper represents the third analytical study, coming after two earlier analytical studies on the TTR/699; that is, a 2018 paper on pre-test predictions of 699 performance and loads, Ref. 1, and an upcoming January 2019 paper on aeroelastic stability analysis of the TTR/699 installed in the 40- by 80-Foot Wind Tunnel, Ref. 2. Reference 8 will present an overview of the entire TTR/699 test program. For completeness, Ref. 3 addresses the development and initial testing of the TTR. Background information on the TTR effort at NASA Ames can be found at the Aeromechanics website: https://rotorcraft.arc.nasa.gov/Research/Facilities/ttr.html. To the authors' knowledge, the full-scale results presented in this paper are the first of their kind. A literature survey brought up several existing correlation studies, but these were either based on small-scale test data (for example, the studies performed by the University of Maryland) or full-scale aircraft flight test data (for example, flight tests conducted by Bell Helicopter). Separately, the 2009 NASA study involving the JVX rotor is relevant (see Ref.4). The JVX is closely similar to the 699 in size and aerodynamics, and is accordingly a good reference for performance calculations. In Ref. 1 (as mentioned above), pre-test reality checks of the current analytical model were made by comparing JVX and 699 predictions in hover and forward flight (airplane mode).
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN61869 , Vertical Flight Society''s Annual Forum and Technology Display; May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    Evaluation of Full Reynolds Stress Turbulence Models in FUN3D for Axisymmetric Jet Flow (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two full seven-equation turbulence models have been implemented into the FUN3D code to evaluate their ability to improve the computation of challenging flows encountered in aerospace propulsion, including mixing flows. These models are the SSG/LRR and Wilcox full second-moment Reynolds stress models. They solve equations for the six components of the Reynolds stress and a seventh equation for the mixing length. Two standard eddy viscosity models are also evaluated for comparison, the Spalart-Allmaras (SA) one-equation model and the Menter Shear Stress Transport (SST-V) two-equation turbulence model. Flow through an axisymmetric reference nozzle is examined at three flow conditions: subsonic unheated, subsonic heated, and near sonic unheated. Centerline profiles of velocity and turbulent kinetic energy and radial profiles of velocity, turbulent kinetic energy and turbulent stresses are examined. characteristics, no significant changes in the downstream flow behavior compared to the baseline case are observed. Furthermore, the total power consumed by the fans for different incoming flow conditions also remain marginally the same. It is hoped that the results, albeit obtained at very low speeds. would serve as a database for this technologically interesting flow field that has not been explored adequately before.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN63722 , AIAA Science and Technology Forum (AIAA SciTech); Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Physical Simulation of Rocket Exhaust Aerodynamics Using Heated Ethane: Conceptual Foundations (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-13
    Description: Heated ethane (C2H6) has been proposed as an alternative to inert gases for use as a motive fluid in the experimental simulation of rocket exhaust plumes. By adjusting stagnation temperature, the isentropic exponent of ethane can be tuned to approximate those produced by common rocket propellants including hydrogen, hypergols, alcohols, and hydrocarbons. As a result, ethane can be made to follow a nozzle expansion process which is nearly identical to realistic rocket engine flow fields. Additionally, its high auto-ignition temperature and resistance to condensation enable the testing of expansion ratios much larger than conventional inertgas testing. NASA SSC has performed quasi-one-dimensional analyses using the Chemical Equilibrium with Applications (CEA) code as a preliminary means to compare flow fields produced by non-reacting ethane to those of reacting combustion products. A LO2/LH2 rocket engine operating at a chamber pressure of 5.0 MPa and a mixture ratio of 6.1 was used as an example case to demonstrate ethanes efficacy as a simulant. Errors for key similarity parameters were compared to legacy cold-flow test methods. Additional errors induced by machining tolerances and chemical impurities were also examined. Results suggest that at a 3% geometric scale and ~500 K ethane stagnation temperature, an error of less than 2.5% throughout the flow field is realistically achievable along the dimensions of Mach number, Reynolds number, pressure ratio, and isentropic exponent. The development of an experimental test bed for validation of this configuration is currently underway.
    Keywords: Aerodynamics
    Type: NASA/TM-2019-220446 , SREP-2220-0003
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    Design of a Slotted, Natural-Laminar-Flow Airfoil for a Transport Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-03
    Description: A 13.49-percent-thick, slotted, natural-laminar-flow airfoil, the S207, for a transport aircraft has been designed and analyzed theoretically. The two primary objectives of high maximum lift, insensitive to roughness, and low profile drag have been achieved. The drag-divergence Mach number is predicted to be greater than 0.70.
    Keywords: Aerodynamics
    Type: NF1676L-34040 , NASA-CR-2019-220403
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    Aerodynamic Performance of Supersonic Parachutes Behind Slender Bodies (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-09
    Description: NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project was launched to investigate the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) parachutes. Three flight tests (October 2017, March 2018 and July 2018) deployed and examined parachutes meant for the upcoming "Mars 2020" mission. Mars-relevant conditions were achieved by performing the tests at high altitudes over Earth on a sounding rocket platform, with the parachute deploying behind a slender body (roughly 1/6-th the diameter of the capsule that will use this parachute for descent at Mars). All three tests were successful and delivered valuable data and imagery on parachute deployment and performance. CFD simulations were used in designing the flight test, interpreting the flight data, and extrapolating the results obtained during the flight test to predict parachute behavior at Mars behind a blunt capsule. This presentation will provide a brief overview of the test program and flight test data, with emphasis on differences in parachute performance due to the leading body geometry.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN71648 , Annual Meeting of the APS Division of Fluid Dynamics; Nov 23, 2019 - Nov 26, 2019; Seattle, WA; United States
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    Experimental Aerodynamic Simulation of Glaze Ice Accretion on a Swept Wing (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-07
    Description: Aerodynamic assessment of icing effects on swept wings is an important component of a larger effort to improve three-dimensional icing simulation capabilities. An understanding of ice-shape geometric fidelity and Reynolds and Mach number effects on iced-wing aerodynamics is needed to guide the development and validation of ice-accretion simulation tools. To this end, wind-tunnel testing was carried out for 8.9% and 13.3% scale semispan wing models based upon the Common Research Model airplane configuration. Various levels of geometric fidelity of an artificial ice shape representing a realistic glaze-ice accretion on a swept wing were investigated. The highest fidelity artificial ice shape reproduced all of the three-dimensional features associated with the glaze ice accretion. The lowest fidelity artificial ice shapes were simple, spanwise-varying horn ice geometries intended to represent the maximum ice thickness on the wing upper surface. The results presented in this paper show that changes in Reynolds and Mach number have only a small effect on the iced-wing aerodynamics relative to the clean-wing configuration. Furthermore, the addition of grit roughness to some lower-fidelity artificial ice shapes resulted in favorable lift and pitching moment comparisons to the wing with the highest fidelity artificial ice shape. For the wing with simple horn ice shapes, the dependence of maximum lift coefficient on horn height and angle are generally consistent with the trends observed for similar experiments conducted on iced airfoils in past research. In terms of usable lift however, the horn height did have a significant effect even for lower horn angles. This could be an important finding since usable lift may be more indicative of the impending iced-swept wing stall and need for additional pitch control than maximum lift coefficient.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN66891 , International Conference on Icing of Aircraft, Engines, and Structures; Jun 17, 2019 - Jun 21, 2019; Minneapolic, MN; United States
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    Preliminary Scale-Resolving Simulations of Laminar-To-Turbulent Transition in Swept-Wing Flow (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-13
    Description: Swept wings and control surfaces are common elements of modern aircraft, and it has been shown both experimentally and theoretically that laminar-to-turbulent transition of the three-dimensional boundary layer that develops over them is highly sensitive to surface roughness. Numerous studies have been conducted on the effect of discrete roughness elements or distributed roughness elements on swept flow transition, however so far limited computational effort has been dedicated to the study of transition over swept wings with randomly distributed micron-sized roughness. In the present work, we set up to reproduce the extensive experimental data base generated by Dagenhart et al for the infinite swept wing NLF(2)-0415. To this purpose, we perform scale-resolving simulations of flow transition over smooth and rough surfaces using a high-order space-time spectral-element Discontinuous-Galerkin solver. Different types of surface roughnesses are implemented by elastically deforming the original mesh. The study shows that the experimental results cannot be accounted for by a perfectly smooth wing and reveals a strong sensitivity of the transition process to the representation of the surface roughness. The crossflow patterns and transition location approach those measured for some of the surface profiles, however a correlation between the wavenumber spectrum of the surface, grid resolution and boundary layer stability is yet to be established.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN69562 , AIAA AVIATION Forum 2019; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Journal of Geophysics - Zeitschrift für Geophysik 46 (2018)
    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148
    Details
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 35 Artikel zu Themengebieten der Geophysik, veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1979.
    Description: Inhaltsverzeichnis: Journal of Geophysics 46 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0008.pdf"〉Wave Propagation in Stratifield Anisotropic Media〈/a〉〈br〉 (Bossy, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0009.pdf"〉Radio Pulse Dispersion in the Ionosphere〈/a〉〈br〉 (Paul, A. K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0010.pdf"〉Ionospheric Absorption and Profiles of Electron Density and Loss-Rate in the Lower Ionosphere〈/a〉〈br〉 (Kotadia, K. M., Gupta, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0011.pdf"〉Effective Energy Reception of the Electron Gas per Created Ion Electron Pair〈/a〉〈br〉 (Bilitza, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0012.pdf"〉Empirical Model of Global Electron Temperature Distribution Between 300 and 700 km Based on Data From Aeros-A〈/a〉〈br〉 (Spenner, K., Plugge, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0013.pdf"〉Intercomparison Between Aeros Electron Temperature Model and Mean Temperature Profiles of Different Incoherent Scatter Radar Stations〈/a〉〈br〉 (Spenner, K., Bilitza, D., Plugge, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0014.pdf"〉Simultaneous Smoothed Variations of Signal Amplitude and Mean Doppler Shift in 42 MHz Auroral Backscatter〈/a〉〈br〉 (Haldoupis, C. I., Sofko, G. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0015.pdf"〉Overnight Statiscal Variation of the North-South Movements of Radio Auroral Irregularities〈/a〉〈br〉 (Haldoupis, C. I., Sofko, G. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0016.pdf"〉Q of Mode 〈sub〉O〈/sub〉S〈sub〉O〈/sub〉〈/a〉〈br〉 (Knopoff, L., Zürn, W., Rydelek, P. A., Yogi, T.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0017.pdf"〉Finite Element Convection Models: Comparison of Shallow and Deep Mantle Convection, and Temperatures in the Mantle 〈/a〉〈br〉 (Kopitzke, U.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0018.pdf"〉Detection Probabilities for Weak Regional Seismic Events〈/a〉〈br〉 (Shapira, A., Kulhánek, O., Wahlström, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0019.pdf"〉Accuracy of Ray Theoretical Seismograms〈/a〉〈br〉 (Červený, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0020.pdf"〉Auroral Particle Fluxes in the Ionosphere〈/a〉〈br〉 (Wilhelm, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0021.pdf"〉The Shape of the Cosmic Ray Modulation Region of the April 30, 1976, Event, as Deduced from HELIOS-1, HELIOS-2, IMP-8, and Neutron Monitor Data〈/a〉〈br〉 (Geranios, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0022.pdf"〉Magnetic Rotational Hysteresis Loss in Titanomagnetites and Titanomaghemites – Application to Non-Destructive Mineral Identification in Basalts〈/a〉〈br〉 (Manson, A. J., O’Donovan, J. B., O’Reilly, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0023.pdf"〉The Geomagnetic Field and Its Secular Variation on Finland and Nearby Countries〈/a〉〈br〉 (Nevanlinna, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0024.pdf"〉Age and Crustal Structure of the Canary Islands〈/a〉〈br〉 (Schmincke, H.-U.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0025.pdf"〉Rinneite-Dating of Episodic Events on Potash Salt Deposits〈/a〉〈br〉 (Lippolt, H. J., Raczek, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0026.pdf"〉Magnetic ULF-Waves in the Vicinity of Active Auroral Forms〈/a〉〈br〉 (Klöcker, N., Theile, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0027.pdf"〉Bursts of Irregular Magnetic Pulsations During the Substorm〈/a〉〈br〉 (Kangas, J., Pikkarainen, T., Golikov, Y., Baransky, L., Troitskaya, V., Sterlikova, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0028.pdf"〉Cosmic Noise Absorption Events and Magnetic Pulsation Activity During Substorms〈/a〉〈br〉 (Wedeken, U., Hillebrand, O., Krenzien, E., Ranta, A., Ranta, H., Voelker, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0029.pdf"〉On the Sources of the 12-Month Wave in the An and As Geomagnetic Activity Indices〈/a〉〈br〉 (Mayaud, P. N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0030.pdf"〉Calculation of the Effect of the Oceans on Geomagnetic Variations With an Application to the Sq Field During the IGY〈/a〉〈br〉 (Hobbs, B. A., Dawes, G. J. K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0031.pdf"〉Localized Source Effects on Magnetotelluric Apparent Resistivities〈/a〉〈br〉 (Quon, C., Vozoff, K., Hoversten, M., Morrison, H. F., Lee, K.-H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0032.pdf"〉Long-Wavelength Magnetic Anomalies as a Source of Information About Deep Crustal Structure〈/a〉〈br〉 (Krutikhovskaya, Z., Pashkevich, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0033.pdf"〉Palaeomagnetism and the Early Magmatic History of Fuerteventura (Canary Islands)〈/a〉〈br〉 (Storetvedt, K. M., Mongstad Våge, H., Aase, S., Løvlie, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0034.pdf"〉Ray Theoretical Seismograms for Laterally Inhomogeneous Structures〈/a〉〈br〉 (Červený, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0035.pdf"〉Macroseismic Field of the Earthquake of September 3, 1978, in the Swabian Jura〈/a〉〈br〉 (Procházková, D., Schneider, G., Schmedes, E., Drimmel, J., Fiegweil, E., Lukeschitz, G., Vogt, J., Courtot, P., Godefroy, P., Grünthal, G., Mayer-Rosa, D., Berger, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0036.pdf"〉Approximate Diffraction Theory for Transparent Half-Planes with Application to Seismic-Wave Diffraction at Coal Seams〈/a〉〈br〉 (Fertig, J., Müller, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0037.pdf"〉Seismic Investigations of the Subcrustal Lithosphere Beneath Fennoscandia〈/a〉〈br〉 (Cassell, B. R., Fuchs, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0038.pdf"〉Northern Part of the Tonga Region: A Complicated Subduction Closure〈/a〉〈br〉 (Hanuš, V., Vaněk, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0039.pdf"〉Palaeomagnetic and Rockmagnetic Properties of the Permian Volcanics in the Western Southern Alps〈/a〉〈br〉 (Heiniger, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0040.pdf"〉Palaeomagnetism of Upper Cretaceous Limestones from the Münster Basin, Germany〈/a〉〈br〉 (Heller, F., Channell, J. E. T.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0041.pdf"〉A Two-Dimensional Magnetometer Array for Ground-Based Observations of Auroral Zone Electric Currents During the International Magnetospheric Study (IMS)〈/a〉〈br〉 (Küppers, F., Untiedt, J., Baumjohann, W., Lange, K., Jones, A. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0046/LOG_0042.pdf"〉Estimation of the Dispersion of Compressional Waves in Rocks From Ultrasonic to Seismic Frequencies〈/a〉〈br〉 (Ramananantoandro, R.)〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 550 ; Geophysik ; AEROS Satellite ; Alps ; Auroral Zone Phenomena ; Canary Islands ; Coal Prospection ; Cosmic Rays ; Cretaceous ; Crust of Earth ; Electromagnetic Induction ; Electromagnetic Wave Propagation ; Explosion Seismology ; Fennoscandia ; Free Oscillations ; Geochronology ; Geomagnetic Activity ; Geomagnetic Field ; Geomagnetic Pulsations ; Ionosphere ; Lithosphere ; Magnetotellurics ; Mantle of Earth ; Palaeomagnetism ; Rock Magnetism ; Salt Rocks ; Secular Variation ; Seismic Quality Factor Q ; Seismic Waves ; Seismicity ; Sq Variation ; Subduction Zones ; Theoretical Seismograms ; ULF Waves ; FID-GEO-DE-7
    Language: English
    Type: anthology_digi
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    CITATION GEO-LEO
  • 41
    facet.materialart.
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    Journal of Geophysics - Zeitschrift für Geophysik 47 (2018)
    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148
    Details
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 34 Artikel zu Themengebieten der Geophysik, veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1980.
    Description: Inhaltsverzeichnis: Journal of Geophysics 47 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0011.pdf"〉Iceland: Evolution, Active Tectonics, and Structure. A Preface〈/a〉〈br〉 (Jacoby, W. R., Björnsson, A., Möller, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0012.pdf"〉Tectonic Framework, Evolution. A Continuum Model of Crustal Generation in Iceland; Kinematic Aspects〈/a〉〈br〉 (Pálmason, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0013.pdf"〉Hawaiian Rifts and Recent Icelandic Volcanism: Expressions of Plume Generated Radial Stress Fields〈/a〉〈br〉 (Wyss, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0014.pdf"〉Observations of the Morphology and Structure of the Sea Floor South and West of Iceland〈/a〉〈br〉 (Johnson, G. L., Pálmason, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0015.pdf"〉Stratigraphy and Paleomagnetism of the Esja, Eyrarfjall and Akrafjall Mountains, SW-Iceland〈/a〉〈br〉 (Kristjansson, L., Fridleifsson, I. B., Watkins, N. D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0016.pdf"〉Magnetic Anomalies (〈i〉ΔZ〈/i〉) in NE-Iceland and Their Interpretation Based on Rock-Magnetic Investigations〈/a〉〈br〉 (Becker, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0017.pdf"〉Palaeointensity Measurement on Postglacial Lavas From Iceland〈/a〉〈br〉 (Schweitzer, Ch., Soffel, H. C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0018.pdf"〉On the Evolution of the Reykjanes Ridge South of 60° N Between 40 and 12 Million Years Before Present〈/a〉〈br〉 (Voppel, D., Rudloff, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0019.pdf"〉Morphology and Magnetic Anomalies North of Iceland〈/a〉〈br〉 (Vogt, P. R., Johnson, G. L., Kristjansson, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0020.pdf"〉Morphology of the Reykjanes Ridge Crest Near 62°N〈/a〉〈br〉 (Jacoby, W. R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0021.pdf"〉New Heat Flow Observations on the Reykjanes Ridge〈/a〉〈br〉 (Bram, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0022.pdf"〉Gravity and a Model of the Median Valley〈/a〉〈br〉 (Collette, B. J., Verhoef, J., de Mulder, A. F. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0023.pdf"〉Deformation, Stress, Seismicity. Statistical Analysis of Damaging Earthquakes and Volcanic Eruptions in Iceland From 1550–1978〈/a〉〈br〉 (Gudmundsson, G., Saemundsson, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0024.pdf"〉Geodetic Measurements and Horizontal Crustal Movements in the Rift Zone of NE-Iceland〈/a〉〈br〉 (Möller, D., Ritter, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0025.pdf"〉Results of Height Measurements in Northern Iceland 1965/1977〈/a〉〈br〉 (Spickernagel, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0026.pdf"〉Gravity and Height Variations During the Present Rifting Episode in Northern Iceland〈/a〉〈br〉 (Torge, W., Kanngieser, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0027.pdf"〉Gravity and Elevation Changes Caused by Magma Movement Beneath the Krafla Caldera, Northeast Iceland〈/a〉〈br〉 (Johnson, G. V., Björnsson, A., Sigurdsson, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0028.pdf"〉Subsidence Events in the Krafla Area, North Iceland, 1975–1979〈/a〉〈br〉 (Tryggvason, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0029.pdf"〉Surface Deformation of the Krafla Fissure Swarm in Two Rifting Events〈/a〉〈br〉 (Sigurdsson, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0030.pdf"〉Seismological Evidence for Lateral Magma Intrusion During the July 1978 Deflation of the Krafla Volcano in NE-Iceland〈/a〉〈br〉 (Einarsson, P., Brandsdóttir, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0031.pdf"〉Measurement of Distance and Tilt Changes in Fissures of Northern Iceland〈/a〉〈br〉 (Pelzer, H., Gerstenecker, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0032.pdf"〉Recent Earthquakes in the Hengill-Hellisheidi Area in SW-Iceland〈/a〉〈br〉 (Foulger, G., Einarsson, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0033.pdf"〉Rock Stress in an Icelandic Thermal Area, With Implications on Stresses in the Oceanic Lithosphere〈/a〉〈br〉 (Voight, B., Simon, R., Thorsteinsson, T., Pálmason, G., Taylor, C., Seret Opzoomer-Talma, S. H., Haimson, B. C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0034.pdf"〉Crustal and Upper Mantle Structure. A Model of Electrical Resistivity Beneath NE-Iceland, Correlation with Temperature〈/a〉〈br〉 (Beblo, M., Björnsson, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0035.pdf"〉A Seismic Study of the Rift Zone in Northern Iceland〈/a〉〈br〉 (Zverev, S. M., Litvinenko, I. V., Pálmason, G., Yaroshevskaya, G. A., Osokin, N. N., Akhmetjev, M. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0036.pdf"〉A Seismic Crustal Study of the Axial Rift Zone in Southwest Iceland〈/a〉〈br〉 (Zverev, S. M., Litvinenko, I. V., Pálmason, G., Yaroshevskaya, G. A., Osokin, N. N.)〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0037.pdf"〉Seismic Structure of the Icelandic Crust Above Layer Three and the Relation Between Body Wave Velocity and the Alteration of the Basaltic Crust〈/a〉〈br〉 (Flóvenz, Ó. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0038.pdf"〉Crustal Structure of the Iceland-Faeroe Ridge〈/a〉〈br〉 (Bott, M. H. P., Gunnarsson, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0039.pdf"〉Reykjanes Ridge Iceland Seismic Experiment (RRISP 77)〈/a〉〈br〉 (Angenheister, G., Gebrande, H., Miller, H., Goldflam, P., Weigel, W., Jacoby, W. R., Pálmason, G., Björnsson, S., Einarsson, P., Pavlenkova, N. I., Zverev, S. M., Litvinenko, I. V., Loncarevic, B., Solomon, S. C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0040.pdf"〉Seismic Structure of Iceland Along RRISP-Profile I〈/a〉〈br〉 (Gebrande, H., Miller, H., Einarsson, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0041.pdf"〉Seismic Structure Along RRISP – Profile I on the Southeast Flank of the Reykjanes Ridge〈/a〉〈br〉 (Goldflam, P., Weigel, W., Loncarevic, B. D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0042.pdf"〉Crustal Development of the Reykjanes Ridge From Seismic Refraction〈/a〉〈br〉 (Bunch, A. W. H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0043.pdf"〉Reykjanes Ridge Crest Studied by Surface Waves With an Earthquake-Pair Technique〈/a〉〈br〉 (Keen, C. E., Fricker, A., Keen, M. J., Blinn, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1015067948_0047/LOG_0044.pdf"〉The Evolution of the Lithosphere at the Southeast Flank of Reykjanes Ridge From Surface Wave Data〈/a〉〈br〉 (Jacoby, W. R., Girardin, N.)〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 550 ; Geophysik ; Asthenosphere ; Crust and Upper Mantle ; Deformation ; Dynamic Models ; Earthquake Statistics ; Evolution of Crust and Lithosphere ; Geodetic Measurements ; Geothermics ; Gravity ; Heat Flow, Geothermics ; History of Geophysics ; lsostasy ; Lithosphere ; Magma Movement ; Magnetic Anomalies ; Magnetotellurics ; Paleomagnetism ; Plate Tectonics ; Plume Hypothesis ; Ridge Model ; Ridge Structure ; Ridge Topography ; Rifting and Volcanism ; Rock Magnetism ; Seafloor Spreading ; Seafloor Morphology ; Seismic Anisotropy ; Seismicity ; Seismic Reflection ; Seismic Refraction ; Stress, Strain ; Surface Waves ; Temperature ; Velocity-Density Systematics ; Viscosity ; FID-GEO-DE-7
    Language: English
    Type: anthology_digi
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    CITATION GEO-LEO
  • 42
    facet.materialart.
    Unknown
    Numerical Study of Turbulent Separation Bubbles with Varying Pressure Gradient and Reynolds Number (2018)
    In:  CASI
    Details
    Publication Date: 2019-06-29
    Description: A family of cases each containing a small separation bubble is treated by direct numerical simulation (DNS), varying two parameters: the severity of the pressure gradients, generated by suction and blowing across the opposite boundary, and the Reynolds number. Each flow contains a well-developed entry region with essentially zero pressure gradient, and all are adjusted to have the same value for the momentum thickness, extrapolated from the entry region to the centre of the separation bubble. Combined with fully defined boundary conditions this will make comparisons with other simulations and turbulence models rigorous; we present results for a set of eight Reynolds-averaged NavierStokes turbulence models. Even though the largest Reynolds number is approximately 5.5 times higher than in a similar DNS study we presented in 1997, the models have difficulties matching the DNS skin friction very closely even in the zero pressure gradient, which complicates their assessment. In the rest of the domain, the separation location per se is not particularly difficult to predict, and the most definite disagreement between DNS and models is near reattachment. Curiously, the better models tend to cluster together in their predictions of pressure and skin friction even when they deviate from the DNS, although their eddy-viscosity levels are widely different in the outer region near the bubble (or they do not rely on an eddy viscosity). Stratfords square-root law is satisfied by the velocity profiles, both at separation and reattachment. The Reynolds-number range covers a factor of two, with the Reynolds number based on the extrapolated momentum thickness equal to approximately 1500 and 3000. This allows tentative estimates of the improvements that even higher values will bring to the model comparisons. The solutions are used to assess models through pressure, skin friction and other measures; the flow fields are also used to produce effective eddy-viscosity targets for the models, thus guiding turbulence-modelling work in each region of the flow.
    Keywords: Aerodynamics
    Type: NF1676L-28495 , Journal of Fluid Mechanics (ISSN 0022-1120) (e-ISSN 1469-7645); 847; 28-70
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    AEROM: NASA's Unsteady Aerodynamic and Aeroelastic Reduced-Order Modeling Software (2018)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The origins, development, implementation, and application of AEROM, NASA's patented reduced-order modeling (ROM) software, are presented. Full computational fluid dynamic (CFD) aeroelastic solutions and ROM aeroelastic solutions, computed at several Mach numbers using the NASA FUN3D CFD code, are presented in the form of root locus plots in order to better reveal the aeroelastic root migrations with increasing dynamic pressure. The method and software have been applied successfully to several con figurations including the Lockheed-Martin N+2 supersonic configuration and the Royal Institute of Technology (KTH, Sweden) generic wind-tunnel model, among others. The software has been released to various organizations with applications that include CFD-based aeroelastic analyses and the rapid modeling of high- fidelity dynamic stability derivatives. Recent results obtained from the application of the method to the AGARD 445.6 wing will be presented that reveal several interesting insights.
    Keywords: Aerodynamics
    Type: NF1676L-29554 , Aerospace (e-ISSN 2226-4310); 5; 2
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    Measurement of Elastic Microfence Deflection for Aerodynamic Flow Sensing (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: Bio-inspired artificial hair sensors have the potential to detect aerodynamic flow features such as stagnation point, flow separation, and flow reattachment that could be beneficial for ight control and performance enhancement of aircraft. In this work, elastic microfence structures were tested on a at-plate setup. The microfences were fabricated from a two-part silicone molded against a template patterned by laser ablation. The response of the microfences to different freestream velocities and to flow reversal at the sensor were recorded via an optical microscope.
    Keywords: Aerodynamics
    Type: NF1676L-28893 , (ISSN 0957-0233) (e-ISSN 1361-6501)
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    Project Link!: Dynamics and Control of In-Flight Wing Tip Docking (2018)
    In:  CASI
    Details
    Publication Date: 2019-06-22
    Description: Project Link! is a NASA-led effort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a dynamic model and control architecture for a system of fixed-wing vehicles with this capability. The dynamic model consists of the 6 degree-of-freedom fixed-wing aircraft equations of motion, a spring-damper-magnet system to represent the linkage force between constituent vehicles, and the NASA-Burnham-Hallock wingtip vortex model to represent the close-proximity aerodynamic interactions between constituents before the linking occurs. The control architecture consists of a guidance algorithm to autonomously drive the constituents towards their linking partners and an inner-loop angular rate controller. A simulation was constructed from the model, and the flight dynamic modes of the linked system were compared to the individual vehicles. Simulation results for both before and after linking are presented.
    Keywords: Aerodynamics
    Type: NF1676L-28271 , Journal of Guidance, Control, and Dynamics (ISSN 0731-5090) (e-ISSN 1533-3884); 41; 11
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    Aeroelastic Optimization with an Economical Transonic Flutter Constraint Using NavierStokes Aerodynamics (2018)
    In:  CASI
    Details
    Publication Date: 2019-06-21
    Description: Structural optimization with a flutter constraint for a vehicle designed to fly in the transonic regime is a particularly difficult task. In this speed range, the flutter boundary is very sensitive to aerodynamic nonlinearities, typically requiring high-fidelity Navier-Stokes simulations. However, the repeated application of unsteady computational fluid dynamics to guide an aeroelastic optimization process is very computationally expensive. This expense has motivated the development of methods that incorporate aspects of the aerodynamic nonlinearity, classical tools of flutter analysis, and more recent methods of optimization. While it is possible to use doublet lattice method aerodynamics, this paper focuses on the use of an unsteady high-fidelity aerodynamic reduced order model combined with successive transformations that allows for an economical way of utilizing high-fidelity aerodynamics in the optimization process. This approach is applied to the common research model wing structural design. The high-fidelity aerodynamics produces a heavier wing than that optimized with doublet lattice aerodynamics. It is found that the optimized lower wing skin thickness distribution using high-fidelity aerodynamics differs significantly from that using doublet lattice aerodynamics.
    Keywords: Aerodynamics
    Type: NF1676L-27633 , Journal of Aircraft (ISSN 0021-8669) (e-ISSN 1533-3868); 55; 4; 1522-1530
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    Nosetip Bluntness Effects on Transition at Hypersonic Speeds: Experimental and Numerical Analysis Under NATO STO AVT-240 (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The existing database of transition measurements in hypersonic ground facilities has established that the onset of boundary layer transition over a circular cone at zero angle of attack shifts downstream as the nosetip bluntness is increased with respect to a sharp cone. However, this trend is reversed at suciently large values of the nosetip Reynolds number, so that the transition onset location eventually moves upstream with a further increase in nosetip bluntness. This transition reversal phenomenon, which cannot be ex- plained on the basis of linear stability theory, was the focus of a collaborative investigation under the NATO STO group AVT-240 on Hypersonic Boundary-Layer Transition Predic- tion. The current paper provides an overview of that e ort, which included wind tunnel measurements in three di erent facilities and theoretical analysis related to modal and nonmodal ampli cation of boundary layer disturbances. Because neither rst and second- mode waves nor entropy-layer instabilities are found to be substantially ampli ed to ini- tiate transition at large bluntness values, transient (i.e., nonmodal) disturbance growth has been investigated as the potential basis for a physics-based model for the transition reversal phenomenon. Results of the transient growth analysis indicate that disturbances that are initiated within the nosetip or in the vicinity of the juncture between the nosetip and the frustum can undergo relatively signi cant nonmodal ampli cation and that the maximum energy gain increases nonlinearly with the nose radius of the cone. This nding does not provide a de nitive link between transient growth and the onset of transition, but it is qualitatively consistent with the experimental observations that frustum transition during the reversal regime was highly sensitive to wall roughness, and furthermore, was dominated by disturbances that originated near the nosetip.
    Keywords: Aerodynamics
    Type: NF1676L-27370 , AIAA SciTech 2018; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Fast Sensitivity-Based Optimal Trajectory Updates for Descent Operations Subject to Time Constraints (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The ability to meet a controlled time of arrival during a continuous descent operation will enable environmentally friendly and fuel efficient descent operations while simultaneously maintaining airport throughput. Previous work showed that guidance strategies based on a frequent recalculation of the optimal trajectory during the descent result in excellent environmental impact mitigation figures while meeting operational constraints in the presence of modelling errors. However, the time lag of recalculating the trajectory using traditional optimisation algorithms could lead to performance degradation and stability issues. This paper proposes an alternative strategy, which allows for fast updates of the optimal trajectory based on parametric sensitivities. Promising results show that the performance of this method is comparable to that of instantaneously recalculating the optimal descent trajectory at each time sample.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-30424 , AIAA/IEEE Digital Avionics Systems Conference (DASC); Sep 23, 2018 - Sep 27, 2018; London, England; United Kingdom
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    Performance of Supersonic Parachutes Behind Slender Bodies (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: NASAs ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project is investigating the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) parachutes. The first two flight tests were carried out in October 2017 and March 2018, while a third test is planned for the fall of 2018. In these tests, Mars-relevant conditions are achieved by deploying the parachutes at high altitudes over Earth using a sounding rocket test platform. As a result, the parachute is deployed behind a slender body (roughly 1/6-th the diameter of the capsule that will use this parachute for descent at Mars). Because there is limited flight and experimental data for supersonic DGBs behind slender bodies, the development of the parachute aerodynamic models was informed by CFD simulations of both the leading body wake and the parachute canopy. This presentation will describe the development of the pre-flight parachute aerodynamic models and compare pre-flight predictions with the reconstructed performance of the parachute during the flight tests. Specific attention will be paid to the differences in parachute performance behind blunt and slender bodies.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN59603 , American Physics Society, Division of Fluid Dynamics; Nov 18, 2018 - Nov 20, 2018; Atlanta,GA; United States
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    Frequency-Domain Deconvolution for Flight Dynamics Applications (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A deconvolution method is presented for estimating input data from measured output data and a model of the dynamic process involved. The method uses an optimal Wiener filter for separating the measured data into signal and noise components, and a high-accuracy Fourier transform for inverting the model dynamics in the frequency domain. The method is an extension of optimal Fourier smoothing, and uses a technique to enhance the contrast between the signal and noise spectra in designing the Wiener filter. The deconvolution method was applied to simulation and flight test data for the purposes of removing unwanted distortions introduced by signal-conditioning filters and sensor dynamics, and for reconstructing turbulence inputs from measured sensor data. Results indicated hat the method performs well given good signal-to-noise levels and accurate models of the dynamic process.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28783 , AIAA Aviation and Aeronautics Forum and Exposition; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Numerical Simulation of a Simplified High-Lift CRM Configuration Embedded with Fluidic Actuators (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Numerical simulations have been performed for a simplified high-lift configuration that is representative of a modern transport airplane. This configuration includes a leading-edge slat, fuselage, wing, nacelle-pylon and a simple hinged flap. The suction surface of the flap is embedded with multiple rows of fluidic actuators to reduce the extent of reversed flow regions and improve the aerodynamic performance of the configuration with flap in a deployed state. In the current paper, a Lattice Boltzmann Method based high-fidelity computational fluid dynamics (CFD) code, known as PowerFLOW is used to simulate the entire flow field associated with this configuration, including the flow inside the actuators. A fully compressible version of the PowerFLOW code that has been validated for high speed flows is used for the present simulations to accurately represent the transonic flow regimes that are encountered in the flow field generated by the actuators operating at higher mass flow (momentum) rates required to mitigate reverse flow regions on the suction surfaces of the main wing and the flap. The numerical solutions predict the expected trends in aerodynamic forces as the actuation levels are increased. More efficient active flow control (AFC) systems and actuator arrangement for lift augmentation are emerging based on the parametric studies conducted here prior to wind tunnel tests. These numerical solutions will be compared with experimental data, once such data becomes available.
    Keywords: Aerodynamics
    Type: AIAA 2018-3063 , NF1676L-28525 , AIAA Aviation Forum 2018; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Practical Aspects of the Frequency Domain Approach for Aircraft System Identification (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Practical aspects of the frequency-domain approach for aircraft system identification are explained and demonstrated. Topics related to experiment design, flight data analysis, and dynamic modeling are included. For demonstration purposes, simulated time series data and simulated flight data from an F-16 nonlinear simulation with realistic noise are used. This approach enables detailed evaluations of the techniques and results, because the true characteristics of the data and aircraft dynamics are known for the simulated data. Analytical techniques and practical considerations are examined for the finite Fourier transform, nonparametric frequency response estimation, parametric modeling in the frequency domain, experiment design for frequency-domain modeling, data analysis and modeling in the frequency domain, and real-time calculations. Flight data from a subscale jet transport aircraft are used to demonstrate some of the techniques and technical issues.
    Keywords: Aerodynamics
    Type: NF1676L-28745 , AIAA Aviation Forum 2018; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Modal Test and Analysis of the NASA Tiltrotor Test Rig (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The Tiltrotor Test Rig (TTR) is being developed at the NASA Ames Research Center for testing full-scaleproprotors in the National Full-scale Aerodynamics Complex (NFAC) wind tunnel. The TTR is currentlyundergoing checkout testing to ensure its proper functionality. Part of the checkout process is a groundvibration test, or shake test, to characterize the modal characteristics of the test rig once it is installed in the wind tunnel. This paper presents a summary of the shake test procedure and an overview of the test results. The results include frequency response functions for a number of different test configurations as well as visualizations of the major mode shapes. Excitation methods included random and swept sine shaking as well as hammer impacts. At the conclusion of this paper, some recommendations are given for future shake tests.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN50736 , AHS Specialist''s Conference on Aeromechanics Design for Transformative Vertical Flight; Jan 16, 2018 - Jan 19, 2018; San Francisco, CA; United States
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    Measurements of Freestream Fluctuations in the NASA Langley 20-Inch Mach 6 Tunnel (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: An experimental campaign was conducted to measure and to characterize the freestream disturbance levels in the NASA Langley Research Center 20-Inch Mach 6 Wind Tunnel. A pitot rake was instrumented with fast pressure transducers, hot wires, and an atomic layer thermopile to quantify the fluctuation levels of pressure, mass flux, and heat flux, respectively. In conjunction with these probe-based measurements, focused laser differential interferometry was used to optically measure density fluctuations. Measurements were made at five nominal different unit Reynolds numbers ranging from (3.28 to 26.5) times 10 (sup 6) per meter. The rake was positioned at two different stream-wise locations and several different roll angles to measure flow uniformity within the test section. In general, noise levels were spatially consistent within the tested region. Pitot pressure fluctuation levels ranged from 0.84 percent at the highest Reynolds number tested to 1.89 percent at the lowest Reynolds number tested. Freestream mass-flux fluctuations remained relatively constant between 1.8-2.5 percent of the freestream. The pressure transducers were also used to determine the dominant disturbance speed and angle of propagation. The disturbances were estimated to travel at approximately 54-81 percent of the freestream speed at an angle of approximately 21-44 degrees from the freestream direction, but these measurements had a significant amount of uncertainty. A comparison to previous measurements of pressure made in 2012 and of mass flux made in 1994 show almost no change in the RMS (Root Mean Square) fluctuation of these flow quantities.
    Keywords: Aerodynamics
    Type: NF1676L-28570
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    Real-Time Parameter Estimation for Flexible Aircraft (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A method for estimating aeroelastic stability and control derivatives for flexible aircraft is developed and demonstrated using flight test data for the X-56A subscale demonstrator. The method uses the equation-error approach with frequency-domain data, and can be applied post-flight or in real time during flight. The non-dimensional aeroelastic forces and moments and the explanatory variables (including generalized displacement, rate, and acceleration states for the vibration modes) are estimated using a finite element model and onboard sensor measurements in both a least squares and Kalman filtering framework. The data are then transformed into the frequency domain for parameter estimation using equation error. This method can result in a more efficient analysis than with other iterative methods, and can leverage existing statistical tools for model structure determination, data collinearity detection, combining multiple maneuvers or prior information, and others to improve model quality.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28533 , AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Heat Transfer Measurements on the Endwall of a Variable Speed Power Turbine Blade Cascade (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Heat transfer measurements were obtained on the endwall and a 2-D section of a variable speed power turbine (VSPT) rotor blade. Infrared thermography was used to help determine the transition of flow from laminar to turbulent as well asdetermine regions of flow separation. Steady state data was obtained for six incidence angles ranging from +50 degree to-17 degree, and at five flow conditions for each angle.
    Keywords: Aerodynamics
    Type: NASA/TM-2018-220033 , E-19632 , GRC-E-DAA-TN60642 , AHS International Annual Forum & Technology Display; May 14, 2018 - May 17, 2018; Phoenix, AZ; United States
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    Active Flutter Suppression Controllers Derived from Linear and Nonlinear Aerodynamics: Application to a Transport Aircraft Model (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Active flutter suppression has been demonstrated in simulation by many researchers, generally using methods based on linear aerodynamics and often with simplistic geometries. In this paper, active flutter suppression is demonstrated in a simulation using a Navier-Stokes aerodynamics code, FUN3D (Fully Unstructured Navier-Stokes Three-Dimensional), and a realistic transport aircraft configuration. This is accomplished using simple observer-feedback controllers derived from linear aeroelastic models, including reduced order models built via FUN3D data. The development of these reduced order models is described here. It is shown that controllers derived from reduced order models of the nonlinear aerodynamics outperform controllers based on linear aerodynamics.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28523 , AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Systems Engineering for the PRANDTL-D 3c Aircraft (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of the Preliminary Research in AerodyNamicDesign to Lower Drag (PRANDTL-D) project is to show that birds fly using a "bell" shaped spanload rather than using an elliptical shaped spanload and to demonstrate the extensive benefits of this alternative spanload. This validation is done by flying a research glider with a twenty five foot wingspan that collects a range of parameters in flight. To ensure the data collection computers and suite of sensors work together and mesh well with the aircraft, systems engineering principles are applied. Needs for new one-off parts require a systems engineering approach as all the criteria of the plane, such as aerodynamics, structures, and avionics, must be taken into account when making decisions. The result of this approach were effective solutions that had a minimal negative impact on other systems that were not related to the original problem.
    Keywords: Aerodynamics
    Type: AFRC-E-DAA-TN62418 , Southern California Conference on Undergraduate Research SCCUR 2018; Nov 17, 2018; Pasadena, CA; United States
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    Scale-Resolving Simulations of Low-Pressure Turbine Cascades with Wall Roughness Using A Spectral-Element Method (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The accurate prediction of wall-roughness effects in turbomachinery is becoming critical as turbine designers address airfoil surface quality and degradation concerns arising from the shift to advanced ceramic matrix composite (CMC) or additively-manufactured airfoils operating in higher temperature environments. In this paper, a recently developed computational capability for accurate and efficient scale-resolving simulations of turbomachinery is extended to analyze the boundary- layer separation and transition characteristics in a rough-wall low-pressure turbine (LPT) cascade. The computational capability is based on an entropy-stable discontinuous-Galerkin spectral-element approach that extends to arbitrarily high orders of spatial and temporal accuracy, and is implemented in an efficient manner for a modern high performance computer architecture. Results from the scale-resolving simulations of both smooth and rough airfoil cascades are presented and compared to previous experiments and numerical simulations. The results show that the suction surface boundary layer undergoes laminar separation, transition, and turbulent reattachment for the smooth airfoil cascade, while in the presence of roughness the separation and transition behavior of the suction surface boundary layer is substantially modified. The differences between the smooth and rough airfoil cascades are then highlighted by a detailed analysis of their respective turbulent flow fields.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN53398 , ASME Turbo Expo 2018; Jun 11, 2018 - Jun 15, 2018; Oslo; Norway
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    Piloted Simulator Evaluation Results of Flight Physics Based Stall Recovery Guidance (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In recent studies, it has been observed that loss of control in flight is the most frequent primary cause of accidents. A significant share of accidents in this category can be remedied by upset prevention if possible, and by upset recovery if necessary, in this order of priorities. One of the most important upsets to be recovered from is stall. Recent accidents have shown that a correct stall recovery maneuver remains a big challenge in civil aviation, partly due to a lack of pilot training. A possible strategy to support the flight crew in this demanding context is calculating a recovery guidance signal, and showing this signal in an intuitive way on one of the cockpit displays, for example by means of the flight director. Different methods for calculating the recovery signal, one based on fast model predictive control and another using an energy based approach, have been evaluated in four relevant operational scenarios by experienced commercial as well as test pilots in the Vertical Motion Simulator at NASA Ames Research Center. Evaluation results show that this approach could be able to assist the pilots in executing a correct stall recovery maneuver.
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN50867 , SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Development of an Integrated Nonlinear Aeroservoelastic Flight Dynamic Model of the NASA Generic Transport Model (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes a recent development of an integrated fully coupled aeroservoelastic flight dynamic model of the NASA Generic Transport Model (GTM). The integrated model couples nonlinear flight dynamics to a nonlinear aeroelastic model of the GTM. The nonlinearity includes the coupling of the rigid-body aircraft states in the partial derivatives of the aeroelastic angle of attack. Aeroservoelastic modeling of the control surfaces which are modeled by the Variable Camber Continuous Trailing Edge Flap is also conducted. The R.T. Jones' method is implemented to approximate unsteady aerodynamics. Simulations of the GTM are conducted with simulated continuous and discrete gust loads..
    Keywords: Aircraft Stability and Control
    Type: ARC-E-DAA-TN50754 , AIAA SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Use of the Ames Check Standard Model for the Validation of Wall Interference Corrections (2018)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The new check standard model of the NASA Ames 11-ft Transonic Wind Tunnel was chosen for a future validation of the facility's wall interference correction system. The chosen validation approach takes advantage of the fact that test conditions experienced by a large model in the slotted part of the tunnel's test section will change significantly if a subset of the slots is temporarily sealed. Therefore, the model's aerodynamic coefficients have to be recorded, corrected, and compared for two different test section configurations in order to perform the validation. Test section configurations with highly accurate Mach number and dynamic pressure calibrations were selected for the validation. First, the model is tested with all test section slots in open configuration while keeping the model's center of rotation on the tunnel centerline. In the next step, slots on the test section floor are sealed and the model is moved to a new center of rotation that is 33 inches below the tunnel centerline. Then, the original angle of attack sweeps are repeated. Afterwards, wall interference corrections are applied to both test data sets and response surface models of the resulting aerodynamic coefficients in interference-free flow are generated. Finally, the response surface models are used to predict the aerodynamic coefficients for a family of angles of attack while keeping dynamic pressure, Mach number, and Reynolds number constant. The validation is considered successful if the corrected aerodynamic coefficients obtained from the related response surface model pair show good agreement. Residual differences between the corrected coefficient sets will be analyzed as well because they are an indicator of the overall accuracy of the facility's wall interference correction process.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN48993 , AIAA SciTech 2018 Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Experimental Investigation of Roughness Effects on Transition on Blunt Spherical Capsule Shapes (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The present contribution reviews recent experimental results of roughness effects on boundary layer transition on capsule geometries with spherical windward geometries. Experiments in three wind tunnel facilities are considered. The ACE Tunnel of Texas AM University, USA, provided Mach 6 experiments with distributed roughness at relatively low Reynolds numbers, 2.5 10(exp 5) 〈 Re(sub d) 〈 5 10(exp 5), with d denoting the capsule diameter. The observed boundary layer transition compared well with correlations based on transient growth theory, even though the roughness heights were in the order of boundary layer thickness. Larger Reynolds numbers, 1 10(exp 6) 〈 Re(sub d) 〈 310(exp 6), could be assessed in the hypersonic Ludwieg tube, HLB, of TU Braunschweig, Germany. Transition is observed at rather low, subcritical roughness values in the order of 20 m for a roughness patch placed about the geometric center of the capsule model. These experiments varied fluctuation levels of the freestream. The authors assume that the observed transitions that occur downstream of the subcritical roughness patch are due to freestream disturbances in the tunnel, which interact with small roughness heights. Additional experiments in the HLB facility with patches of larger roughness height support the relevance of transient growth theory for low-to-medium roughness heights, relative to boundary layer thickness. The effects of Reynolds numbers and total flow enthalpy on transition with isolated roughness were investigated in the HIEST facility of JAXA, Japan. Here, a model insert with roughness elements of varying height for tripping transition to turbulence was employed. The results are compared to known trip effectiveness correlations for isolated roughness. Overall, the transient growth correlation seems to represent roughness-induced transition behavior on the ACE and HLB entry capsule shapes with roughness over the entire capsule surface. These experiment are however for perfect gases. Comparable experiments on roughness induced transition in a high-enthalpy facility are still needed to confirm the validity of transient-growth correlation for vehicle design.
    Keywords: Aerodynamics
    Type: JSC-E-DAA-TN60438 , STO-TR-AVT-240 , Benchmarks in Multidisciplinary Optimization and Design for Affordable Military Vehicles
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    Progress in Accuracy & Stability Improvement of Nonlinear Filter Methods for Long Time Integration of Compressible Flows (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN56933 , International Conference on Spectral and High Order Methods (ICOSAHOM-2018); Jul 09, 2018 - Jul 13, 2018; London; United Kingdom
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    Nonlinear Evolution and Breakdown of Azimuthally Compact Crossflow Vortex Pattern over a Yawed Cone (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Hypersonic boundary-layer flows over a circular cone at moderate angle of incidence can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to the more efficient excitation of stationary crossflow vortices by surface roughness, a possible path to transition in such flows corresponds to rapid amplification of the high-frequency secondary instabilities of finite amplitude stationary crossflow vortices. In the present paper, the previous analyses of crossflow instability over a 7- degree half-angle, yawed circular cone in a Mach 6 free stream have been extended to the nonlinear evolution of azimuthally localized crossflow vortex packets and the amplification characteristics and nonlinear breakdown of high-frequency secondary instabilities associated with those packets. A comparison between plane marching PSE and direct Navier-Stokes simulations (DNS) reveals favorable agreement in regard to mode shapes, most amplified disturbance frequencies, and N-factor evolution. In contrast, the quasi-parallel predictions are found to result in severe underprediction of the N-factors. The direct numerical simulations also indicate that the breakdown of secondary instabilities in a 3D hypersonic boundary layer shares certain common features with the previous computations of crossflow transition over subsonic swept wings.
    Keywords: Aerodynamics
    Type: NF1676L-27338 , AIAA SciTech 2018; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Computational Fluid Dynamics Analysis of the Stall Characteristics of a Wing Design Based on Prandtl's Minimum Induced Drag (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Stall characteristics of a wing whose design was based on Prandtls minimum induced drag analysis is presented. Flow field is resolved using RANS CFD (Computational Fluid Dynamics) solver OVERFLOW-2. Both in freestream and in ground effect are analyzed. In addition, effect of low-Mach preconditioner on the stall characteristic is presented. Results show that simulations that lack preconditioner predicts higher stall angle as well as much more benign behavior near the stall angle. Stall analysis in freestream show that flow begins to separate at the inboard region. The flow at the tip remains attached until approximately 19.0 degrees angle of attack.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN48257 , AIAA Applied Aerodynamics Conference; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States|AIAA Aviation and Aeronautics Forum (Aviation 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Heat Transfer Measurements on the Endwall of a Variable Speed Power Turbine Blade Cascade (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Heat transfer measurements were obtained on the endwall of a 2-D section of a variable speed power turbine (VSPT) rotor blade linear cascade. Infrared thermography was used to help determine the transition of flow from laminar to turbulent as well as determine regions of flow separation. Steady state data was obtained for six incidence angles ranging from +15.8 deg to -51 deg, and at five flow conditions for each angle. Nusselt number was used as a method to visualize flow transition and separation on the endwall surface and showed the effects of secondary flows on the surface. Nusselt correlation with Reynolds number from multiple flow conditions was used to plot local values of the correlation exponent and indicated the state of the local boundary layer as the flow transitioned from laminar to turbulent as well as secondary flow features.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN54896 , AHS International Annual Forum & Technology Display; May 14, 2018 - May 17, 2018; Phoenix, AZ; United States
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    Design, Development, and Flight Evaluation of Pilot Displays and Long-Track Control for Wake Surfing Applications (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: These slides are the companion to the paper on the ACT experiment flown using a G-III autopilot and ADS-B datalink.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN58037 , AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Spanwise Adaptive Wing (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This presentation discusses the NASA Armstrong PTERA-SAW flight simulation. The uses of this simulation are to study the aerodynamic effects of moving outer wing panels in flight, develop a flight control system, flight safety analysis, mission planning, flight envelope expansion, and post-flight data analysis.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN57916 , AIAA Aviation 2018; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Performance Calculations for a Boundary-Layer-Ingesting Fan Stage from Sparse Measurements (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A test of the Boundary Layer Ingesting-Inlet / Distortion-Tolerant Fan was completed in NASA Glenn's 8-Foot by 6-Foot supersonic wind tunnel. Inlet and fan performance were measured by surveys using a set of rotating rake arrays upstream and downstream of the fan stage. Surveys were conducted along the 100 percent speed line and a constant exit corrected flow line passing through the aerodynamic design point. These surveys represented only a small fraction of the data collected during the test. For other operating points, data was recorded as snapshots without rotating the rakes which resulted in a sparser set of recorded data. This paper will discuss analysis of these additional, lower measurement density data points to expand our coverage of the fan map. Several techniques will be used to supplement the snapshot data at test conditions where survey data also exists. The supplemented snapshot data will be compared with survey results to assess the quality of the approach. Effective methods will be used to analyze the data set for which only snapshots exist.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN50320 , AIAA SciTech 2018; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Code TS: Entry Systems and Technology Division (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The TS division (Entry Systems and Technology Division) includes people who 1) Help design spacecraft for different exploration missions; 2) Figure out how hot the environments around a spacecraft will get; 3) Invent new materials that can protect the spacecraft; 4) Figure out how those materials will behave on a spacecraft and how thick they need to be; 5) Plan and perform tests on those materials and spacecraft designs to prove they will fly successfully; and 6) Help get those spacecraft ready to launch. This presentation will describe a little bit about all 6 areas.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN63834 , NASA Ames Holiday Festival; Dec 08, 2018; Moffett Field, CA; United States
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    Wall-Resolved Large Eddy Simulations of Transonic Shock-Induced Flow Separation (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper reports the wall-resolved large eddy simulations of shock-induced boundary layer separation over an axisymmetric bump for a flow Mach number of 0.875 and a chord-based Reynolds number of 2.763 million. The incoming boundary layer has a momentum-thickness Reynolds number of 6600 at one and a half chord lengths upstream of the leading edge. The calculations simulate the experiment by Bachalo and Johnson (AIAA Journal, Vol. 24, No. 3, 1986), except that the tunnel walls are ignored and the simulations are performed assuming free air with as many as 24 billion grid points. The effects of domain span, grid resolution and time step on the predictions are examined. The results are found to show some sensitivity to the studied parameters. Owing to the outer boundary conditions, the predicted surface pressure distribution as well as the flow separation and reattachment locations tend to agree better with the experimental results from the larger (6 6 ft) tunnel than those from the smaller (2 2 ft) tunnel. The predicted Reynolds shear stress profiles in the separated region differ by as much as 31%from the experimental results that were only obtained in the smaller tunnel. The most accurate surface pressure distribution obtained in this study lies within the scatter of the measurements taken in the two facilities.
    Keywords: Aerodynamics
    Type: NF1676L-27292 , AIAA SciTech 2018; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    Aerothermal Design of a Common Probe for Multiple Planetary Destinations (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The idea of a single design of a capsule, for atmospheric entry at Venus, Jupiter, Saturn, Uranus, and Neptune and delivery of payloads for in situ scientific experiments, is currently being pursued by a team of scientists and engineers drawn from four NASA centers - Ames, Langley, JPL, and Goddard. For notional suites of instruments (the selection depending on the destination), interplanetary trajectories have been developed by team members at JPL and Goddard. Using the entry states provided by these trajectories, 3DOF atmospheric flight trajectories have been developed by Langley [4] and Ames. The range of entry flight path angles for each destination is chosen such that the deceleration load lies between 50 g (shallow) and 150-200 g (steep) for a 1.5 m (diameter) rigid aeroshell based on a 45deg sphere-cone geometry and an entry mass of 400 kg.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN53538 , International Planetary Probe Workshop; Jun 11, 2018 - Jun 15, 2018; Boulder, CO; United States
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    High-resolution Wave Propagation Method for Stratified Flows (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: The implementation of the multidimensional f-waves Riemann solver for the time-dependent, three-dimensional, nonhydrostatic, meso- and microscale atmospheric flows is described in detail. The Riemann solver employs flux-based wave decomposition (f-waves) for the calculation of Godunov fluxes in which the flux differences are written directly as the linear combination of the right eigenvectors of the hyperbolic system. The scheme incorporates the source term due to gravity without introducing discretization errors which is an important property in the context of atmospheric flows. The resulting flow solver is conservative, accurate, stable, and well-balanced. The implementation of the solver is evaluated using benchmark test cases for atmospheric dynamics.
    Keywords: Aerodynamics
    Type: NF1676L-28626 , 2018 AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Formation Flight System Extremum-Seeking-Control Using Blended Performance Parameters (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: An extremum-seeking control system for formation flight that uses blended performance parameters in a conglomerate performance function that better approximates drag reduction than performance functions formed from individual measurements. Generally, a variety of different measurements are taken and fed to a control system, the measurements are weighted, and are then subjected to a peak-seeking control algorithm. As measurements are continually taken, the aircraft will be guided to a relative position which optimizes the drag reduction of the formation. Two embodiments are discussed. Two approaches are shown for determining relative weightings: "a priori" by which they are qualitatively determined (by minimizing the error between the conglomerate function and the drag reduction function), and by periodically updating the weightings as the formation evolves.
    Keywords: Aircraft Stability and Control
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    Full-Scale Testing of Active Flow Control Enhanced Vertical Tail (2018)
    In:  Other Sources
    Details
    Publication Date: 2019-10-26
    Description: This paper describes wind tunnel test results from a joint NASA/Boeing research effort to advance active flow control (AFC) technology to enhance aerodynamic efficiency. A full-scale Boeing 757 vertical tail model equipped with 37 sweeping jet actuators was tested at the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel (40x80) at NASA Ames Research Center. The model was tested at a nominal airspeed of 100 knots and across rudder deflections and sideslip angles that covered the vertical tail flight envelope. The flow separation control optimization was performed at the maximum rudder deflection of 30 and sideslip angles of 0 and -7.5. Greater than 20% increase in side force were achieved at maximum rudder deflection and the two sideslip angles with a 31-actuator configuration. AFC caused significant increases in suction pressure on the actuator side and associated side force enhancement. The successful demonstration of this application cleared the way for a subsequent flight demonstration on the Boeing 757 ecoDemonstrator in 2015.
    Keywords: Aerodynamics
    Type: NF1676L-27629 , AIAA Journal (ISSN 0001-1452) (e-ISSN 1533-385X); 56; 9; 3393-3398
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    Dynamics and Control of In-Flight Wing Tip Docking (2018)
    In:  CASI
    Details
    Publication Date: 2019-10-19
    Description: Project Link! is a NASA-led effort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a dynamic model and control architecture for a system of fixed-wing vehicles with this capability. The dynamic model consists of the 6 degree-of-freedom fixedwing aircraft equations of motion, a spring-damper-magnet system to represent the linkage force between constituent vehicles, and the NASA-Burnham-Hallock wingtip vortex model to represent the close-proximity aerodynamic interactions between constituents before the linking occurs. The control architecture consists of a guidance algorithm to autonomously drive the constituents towards their linking partners and an inner-loop angular rate controller. A simulation was constructed from the model, and the flight dynamic modes of the linked system were compared to the individual vehicles. The main contributions of this work are twofold. First is the introduction of close-proximity aerodynamic effects to create a realistic simulation framework for this problem. Second is the application of a sophisticated leaderfollower guidance algorithm to achieve in-air wingtip docking. Simulation results for both before and after linking are presented.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-28646 , Journal of Guidance, Control, and Dynamics (ISSN 0731-5090) (e-ISSN 1533-3884); 41; 11; 2327-2337
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    Nosetip Bluntness Effects on Transition at Hypersonic Speeds: Experimental and Numerical Analysis (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-08
    Description: The existing database of transition measurements in hypersonic ground facilities has established that the onset of boundary layer transition over a circular cone at zero angle of attack shifts downstream as the nosetip bluntness is increased with respect to a sharp cone. However, this trend is reversed at sufficiently large values of the nosetip Reynolds number, so that the transition onset location eventually moves upstream with a further increase in nosetip bluntness. This transition reversal phenomenon, which cannot be explained on the basis of linear stability theory, was the focus of a collaborative investigation under the NATO STO group AVT-240 on Hypersonic Boundary-Layer Transition Prediction. The current paper provides an overview of that effort, which included wind tunnel measurements in three different facilities and theoretical analysis related to modal and nonmodal amplification of boundary layer disturbances. Because neither first and second-mode waves nor entropy-layer instabilities are found to be substantially amplified to initiate transition at large bluntness values, transient (i.e., nonmodal) disturbance growth has been investigated as the potential basis for a physics based model for the transition reversal phenomenon. Results of the transient growth analysis indicate that stationary disturbances that are initiated within the nosetip or in the vicinity of the juncture between the nosetip and the frustum can undergo relatively significant nonmodal amplification and that the maximum energy gain increases nonlinearly with the nose radius of the cone. This finding does not provide a definitive link between transient growth and the onset of transition, but it is qualitatively consistent with the experimental observations that frustum transition during the reversal regime was highly sensitive to wall roughness, and furthermore, was dominated by disturbances that originated near the nosetip. Furthermore, the present analysis shows significant nonmodal growth of traveling disturbances that peak within the entropy layer and could also play a role in the transition reversal phenomenon.
    Keywords: Aerodynamics
    Type: NF1676L-29701
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    Laser Tracker Utilization Methodology in Measuring Truth Trajectories for INS Testing on 6 Degree of Freedom Table at the Marshall Space Flight Center's Contact Dynamics Simulation Laboratory with Lessons Learned (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: When performing Inertial Navigation System (INS) testing at the Marshall Space Flight Center's (MSFC) Contact Dynamics Simulation Laboratory (CDSL) early in 2017, a Leica Geosystems AT901 Laser Tracker system (LLT) measured the twist & sway trajectories as generated by the 6 Degree Of Freedom (6DOF) Table in the CDSL. These LLT measured trajectories were used in the INS software model validation effort. Several challenges were identified and overcome during the preparation for the INS testing, as well as numerous lessons learned. These challenges included determining the position and attitude of the LLT with respect to an INS-shared coordinate frame using surveyed monument locations in the CDSL and the accompanying mathematical transformation, accurately measuring the spatial relationship between the INS and a 6DOF tracking probe due to lack of INS visibility from the LLT location, obtaining the data from the LLT during a test, determining how to process the results for comparison with INS data in time and frequency domains, and using a sensitivity analysis of the results to verify the quality of the results. While many of these challenges were identified and overcome before or during testing, a significant lesson on test set-up was not learned until later in the data analysis process. It was found that a combination of trajectory-dependent gimbal locking and environmental noise introduced non-negligible noise in the angular measurements of the LLT that spanned the evaluated frequency spectrum. The lessons learned in this experiment may be useful for others performing INS testing in similar testing facilities.
    Keywords: Aerodynamics
    Type: M17-6256 , AAS Guidance and Control Conference 2018; Feb 02, 2018 - Feb 08, 2018; Breckenridge, CO; United States
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    The Evaluation of Cryogenic Force Balance Calibration Methodologies with Respect to Wind Tunnel Results (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Independent tests of the NASA Common Research Model (CRM) at NASA's National Transonic Facility (NTF) and the European Transonic Windtunnel (ETW) revealed discrepancies at low operating temperatures and high Reynolds numbers that warranted further investigation. Since each facility used their own force balance for their tunnel entry, one suggestion for the discrepancy was the temperature compensation methodology developed and applied for each balance. This hypothesis is explored through simulation and experimentally. Independent calibrations of NASA's NTF-118A balance at NASA Langley and ETW reveal discrepancies in the thermal compensation of the normal force and pitching moment primary sensitivities with temperature, while the axial force primary sensitivities are in good agreement. The application of the force balance calibrations performed at NASA and ETW to the prior wind tunnel data suggests that the thermal compensation discrepancies are an order of magnitude less than the discrepancies observed between the wind tunnel aerodynamic coefficients.
    Keywords: Aerodynamics
    Type: NF1676L-29145 , International Symposium on Strain-Gage Balances; May 14, 2018 - May 17, 2018; Cologne; Germany
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    Output Measurement Equations for Flexible Aircraft Flight Dynamics (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A summary of output measurement equations for onboard sensors used in flight testing of flexible aircraft is presented. These equations include the effects of structural flexibility and are considerably more complex than the standard equations for rigid-body aircraft. The output equations discussed include accelerations from linear accelerometers, strains, angular rates, angular accelerations, Euler angles, true airspeed, and air flow angles. The output equations are derived in full form and then simplified in some cases. Linearized output equations, suitable for state-space or transfer function models, are also developed. Example flight test data from the X-56A subscale aeroelastic demonstrator is discussed, for reference.
    Keywords: Aircraft Stability and Control
    Type: NASA/TM-2018-220102 , L-20956 , NF1676L-31027
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    Convergence Analysis of Turbulent Flow Solutions (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Data from the "Turbulence Modeling Resource" website for turbulent flow over an NACA-0012 airfoil is analyzed to determine the convergence behavior of three second-order CFD (Computational Fluid Dynamics) codes: CFL3D (Computational Fluids Lab 3 Dimensional flow solver), FUN3D (Fully Unstructured Navier-stokes flow solver), and TAU (German Aerospace Center (DLR) 2 dimensional code for unstructured hybrid grids solving the Reynolds-Averaged Navier-Stokes equations or the Euler equations). The convergence of both integrated properties and pointwise data are examined. Several different methods for estimating errors and computing convergence rates are compared. A high-order extension to the Richardson extrapolation is developed that improves the accuracy of the mesh limit values and provides a quantitative estimate of the threshold of the asymptotic regime. The coefficient of total drag exhibits second-order convergence for all three codes, and convergence is monotone over a sequence of 7 grids. Other force coefficients are not so well behaved. The convergence rates of the viscous component of drag on the three nest grids ranges from 3:0 for CFL3D to 1:0 for FUN3D. The three codes are converging to similar but not identical solutions. The largest differences between the codes are in the coefficient of lift for which the difference between CFL3D and FUN3D is greater than 10 (sup minus 4). The best agreement occurs in the viscous component of drag, which is the only force component for which all three codes are converging towards each other at a rate of second-order. The agreement between the two unstructured grid codes is good with all properties except lift converging towards common values at a rate of second-order. No one code was universally better than the other. The TAU code has the lowest error in total drag, FUN3D has the lowest error in lift, and CFL3D has the lowest error in the viscous component of drag.
    Keywords: Aerodynamics
    Type: NASA/TM-2018-220106 , L-20961 , NF1676L-31175
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    FUN3D Manual: 13.4 (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This manual describes the installation and execution of FUN3D version 13.4, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
    Keywords: Aerodynamics
    Type: NASA/TM-2018-220096 , L-20969 , NF1676L-31476
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    Using Pressure Sensitive Paint to Measure Aerodynamic Forces on a Rotor Blade in Hover (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on rotorcraft blades in hover at the Rotor Test Cell located in the 14- by 22-Foot Subsonic Tunnel complex at the NASA Langley Research Center. This work builds upon previous entries and focused on collecting measurements from the upper and lower surface simultaneously. From these results, normal force (F (sub z)) values can be obtained. To date, this is the first time that the Pressure Sensitive Paint technique has been used for these types of measurements on rotor blades. In addition, several areas of improvement have been identified and are currently being developed for future testing.
    Keywords: Aerodynamics
    Type: NF1676L-31309 , NASA/TM-2018-220093 , L-20965
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    FUN3D Manual: 13.3 (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This manual describes the installation and execution of FUN3D version 13.3, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
    Keywords: Aerodynamics
    Type: NASA/TM-2018-219808 , L-20909 , NF1676L-29418
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    Characterization of Freestream Disturbances in Conventional Hypersonic Wind Tunnels (2018)
    In:  CASI
    Details
    Publication Date: 2019-12-13
    Description: While low disturbance (quiet) hypersonic wind tunnels are believed to provide more reliable extrapolation of boundary layer transition behavior from ground to flight, the presently available quiet facilities are limited to Mach 6, moderate Reynolds numbers, low freestream enthalpy, and subscale models. As a result, only conventional (noisy) wind tunnels can reproduce both Reynolds numbers and enthalpies of hypersonic flight configurations, and must therefore be used for flight vehicle test and evaluation involving high Mach number, high enthalpy, and larger models. This article outlines the recent progress and achievements in the characterization of tunnel noise that have resulted from the coordinated effort within the AVT-240 specialists group on hypersonic boundary layer transition prediction. New Direct Numerical Simulation datasets elucidate the physics of noise generation inside the turbulent nozzle wall boundary layer, characterize the spatiotemporal structure of the freestream noise, and account for the propagation and transfer of the freestream disturbances to a pitot-mounted sensor. The new experimental measurements cover a range of conventional wind tunnels with different sizes and Mach numbers from 6 to 14 and extend the database of freestream fluctuations within the spectral range of boundary layer instability waves over commonly tested models. Prospects for applying the computational and measurement datasets for developing mechanism-based transition prediction models are discussed.
    Keywords: Aerodynamics
    Type: NF1676L-29893 , Journal of Spacecraft and Rockets (ISSN 0022-4650) (e-ISSN 1533-6794); 56; 2; 357-368
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    Study of Laminar-Turbulent Transition Modeled by Amplification Factor Transport Within the LAVA Solver (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: The Amplification Factor Transport (AFT) transition model proposed by Coder and Maughmer is implemented in the unstructured and curvilinear Reynolds-Averaged Navier-Stokes (RANS) solvers of the Launch Ascent and Vehicle Aerodynamics (LAVA) platform. It is coupled to the Spalart-Allmaras (SA) turbulence model through a modified intermittency variable. As part of the model verification and validation phase, laminar-turbulent transition is studied over 2D flat plates, wind turbine and general aviation airfoils, as well as a 3D inclined prolate spheroid and the JAXA Standard Model (JSM). This work will analyze the sensitivity of the results to grid refinement, grid paradigm, flow conditions and numerical schemes. The numerical efficiency of the unstructured and curvilinear solvers will be compared and convergence acceleration techniques will be explored to address a broad range of aerodynamics applications.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN49782 , 2018 AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Using Adaptive Mesh Refinement to Study Grid Resolution Effects for Shock/Boundary-Layer Interactions (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Adaptive Mesh Refinement (AMR) promises a much more computationally efficient meansto obtain a discrete approximation to a continuous boundary value problem of a specifiedaccuracy than classic isotropic grid refinement. The AMR capability of OVERFLOW is utilizedto provide estimates of the exact analytical solutions to problems of interest to turbulencemodeling. Predictions of surface pressure and skin friction, essentially the state of stress at thesurface, shows little difference with grids believed to be "grid resolved." Velocity profiles, on theother hand, show marked differences in flows with shocks. The AMR method, as implementedin OVERFLOW2.2k, appears to provide the ability to produce arbitrarily accurate solutionsat a predictable cost much smaller than classic uniform mesh refinement.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN58039 , 2018 AIAA AVIATION Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Distributed-Flap Layout Trade Study on a Highly Flexible Common Research Model (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN58800 , AIAA Aviation Forum 2018; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    The NASA Juncture Flow Test as a Model for Effective CFD/Experimental Collaboration (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Juncture Flow test, whose purpose is CFD validation for wing juncture trailing edge separation and progression, was designed from the outset to be a highly collaborative effort between CFD computationalists and experimentalists. This paper highlights key aspects of the planning and execution of the project, which has recently completed its first phase of wind tunnel testing. The joint CFD/experimental team is described, and its accomplishments to date are summarized.
    Keywords: Aerodynamics
    Type: NF1676L-28138 , AIAA Aviation and Aeronautics Forum and Exposition; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Design, Development, and Flight Evaluation of Pilot Displays and Long-Track Control for Wake Surfing Applications (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: From April to May 2017, the National Aeronautics and Space Administration Armstrong Flight Research Center completed a series of flights with a trail C-20A airplane surfing in the wake of a Gulfstream III airplane using a commercially available datalink as the primary communication between the two aircraft. The purpose of this test was to characterize the aerodynamic benefits received by the trail airplane flying in the upwash portion of the wake generated from the lead airplane. Lateral and vertical relative position to the wake were automatically controlled through an experimental programmable autopilot on the C-20A airplane. Long-track, the separation distance between the two aircraft, was maintained by test pilots managing throttle position using customized cockpit displays. These displays provided the pilots with throttle cues for maintaining long-track position and situational awareness of the wake vortex relative to the position of the trail airplane. Flight testing demonstrated the ability of the pilots to use these displays to maintain a safe long-track distance, but found there to be trades between tracking performance and the frequency of throttle motion. The wake awareness display provided the pilots with adequate situational awareness of the wake vortex during the flight experiment. This paper presents a summary of the design, development, and flight evaluation of the pilot displays and long-track control.
    Keywords: Aircraft Stability and Control
    Type: AFRC-E-DAA-TN54320 , AIAA Aviation and Aeronautics Forum and Exposition; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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    Transition Prediction in Hypersonic Boundary Layers Using Receptivity and Freestream Spectra (2017)
    In:  CASI
    Details
    Publication Date: 2019-06-15
    Description: Boundary-layer transition in hypersonic flows over a straight cone can be predicted using measured freestream spectra, receptivity, and threshold values for the wall pressure fluctuations at the transition onset points. Simulations are performed for hypersonic boundary-layer flows over a 7-degree half-angle straight cone with varying bluntness at a freestream Mach number of 10. The steady and the unsteady flow fields are obtained by solving the two-dimensional Navier-Stokes equations in axisymmetric coordinates using a 5th-order accurate weighted essentially nonoscillatory (WENO) scheme for space discretization and using a third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The calculated N-factors at the transition onset location increase gradually with increasing unit Reynolds numbers for flow over a sharp cone and remain almost the same for flow over a blunt cone. The receptivity coefficient increases slightly with increasing unit Reynolds numbers. They are on the order of 4 for a sharp cone and are on the order of 1 for a blunt cone. The location of transition onset predicted from the simulation including the freestream spectrum, receptivity, and the linear and the weakly nonlinear evolutions yields a solution close to the measured onset location for the sharp cone. The simulations overpredict transition onset by about twenty percent for the blunt cone.
    Keywords: Aerodynamics
    Type: NF1676L-26446 , AIAA Journal (ISSN 0001-1452) (e-ISSN 1533-385X); 56; 1; 193-208
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    Instability Wave-Streak Interactions in a Supersonic Boundary Layer (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-26
    Description: Optimal initial conditions for transient growth in a two-dimensional boundary layer flow correspond to stationary, counter-rotating vortices that subsequently develop into streamwise elongated streaks, which are characterized by an alternating pattern of low and high streamwise velocity. For incompressible flows, previous studies have shown that boundary layer modulation due to streaks below a threshold amplitude level can stabilize the Tollmien-Schlichting instability waves, resulting in a delay in the onset of laminar-turbulent transition. In the supersonic regime, the linearly, most-amplified waves become three-dimensional, corresponding to oblique, first-mode waves. This change in the character of dominant instabilities leads to an important change in the transition process, which is now dominated by oblique breakdown via nonlinear interactions between pairs of first-mode waves that propagate at equal but opposite angles with respect to the free stream. Because the oblique breakdown process is characterized by a rapid amplification of stationary streamwise streaks, artificial excitation of such streaks may be expected to promote transition in a supersonic boundary layer. Indeed, suppression of those streaks has been shown to delay the onset of transition in prior literature. Consistent with those findings, the present study shows that optimally growing stationary streaks indeed destabilize the first-mode waves, but only when the spanwise wavelength of the instability waves is equal to or smaller than twice the streak spacing. Transition in a benign disturbance environment typically involves first-mode waves with significantly longer spanwise wavelengths, and hence, these waves are stabilized by the optimal growth streaks. Thus, as long as the amplification factors for the destabilized, short wavelength instability waves remain below the threshold level for transition, a significant net stabilization is achieved, yielding a transition delay that is comparable to the length of the laminar region in the uncontrolled case.
    Keywords: Aerodynamics
    Type: NF1676L-26301 , Journal of Fluid Mechanics (ISSN 0022-1120) (e-ISSN 1469-7645); 831; 524-553
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    Unseeded Velocity Measurements Around a Transonic Airfoil Using Femtosecond Laser Tagging (2017)
    In:  CASI
    Details
    Publication Date: 2019-06-11
    Description: Femtosecond laser electronic excitation tagging (FLEET) velocimetry was used to study the flowfield around a symmetric, transonic airfoil in the NASA Langley 0.3-m TCT facility. A nominal Mach number of 0.85 was investigated with a total pressure of 125 kPa and total temperature of 280 K. Two-components of velocity were measured along vertical profiles at different locations above, below, and aft of the airfoil at angles of attack of 0, 3.5, and 7. Velocity profiles within the wake showed sufficient accuracy, precision, and sensitivity to resolve both the mean and fluctuating velocities and general flow physics such as shear layer growth. Evidence of flow separation is found at high angles of attack. Velocity measurements were assessed for their accuracy, precision, dynamic range, spatial resolution, and overall measurement uncertainty as they relate to the present experiments. Measurement precisions as low as 1 m/s were observed, while the velocity dynamic range was found to be nearly a factor of 500. The spatial resolution of between 1 mm and 5 mm was found to be primarily limited by the FLEET spot size and advection of the flow. Overall measurement uncertainties ranged from 3 to 4 percent.
    Keywords: Aerodynamics
    Type: NF1676L-26518 , AIAA Journal (ISSN 0001-1452) (e-ISSN 1533-385X); 55; 12; 4142-4154
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    Flight-Test Techniques for Quantifying Pitch Rate and Angle-of-Attack Rate Dependencies (2017)
    In:  CASI
    Details
    Publication Date: 2019-06-11
    Description: Three different types of maneuvers were designed to separately quantify the pitch rate and angle-of-attack rate contributions to the nondimensional aerodynamic pitching moment coefficient. These maneuvers combined pilot inputs and automatic multisine excitations, and they were demonstrated with the subscale T-2 and Bat-4 airplanes using the NASA Airborne Subscale Transport Aircraft Research flight-test facility. Stability and control derivatives (in particular, Cmq and Cm) were accurately estimated from the flight-test data. These maneuvers can be performed with many types of aircraft, and the results can be used to improve physical insight into the flight dynamics, facilitate more accurate comparisons with wind-tunnel experiments or numerical investigations, and increase simulation prediction fidelity.
    Keywords: Aircraft Stability and Control
    Type: NF1676L-26357 , Journal of Aircraft (ISSN 0021-8669) (e-ISSN 1533-3868); 54; 6; 2367-2377
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    Aerodynamic Coefficients from Aeroballistic Range Testing of Deployed- and Stowed-SIAD SFDT Models (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This report documents a ballistic-range test campaign conducted in 2012 in order to estimate the aerodynamic stability characteristics of two configurations of the Supersonic Flight Dynamics Test (SFDT) vehicle prior to its initial flight in 2014. The SFDT vehicle was a test bed for demonstrating several new aerodynamic decelerator technologies then being developed under the Low-Density Supersonic Decelerator (LDSD) Project. Of particular interest here is the Supersonic Inflatable Aerodynamic Decelerator (SIAD), an inflatable attached torus used to increase the drag surface area of an entry vehicle during the supersonic portion of the entry trajectory. Two model configurations were tested in the ballistic range: one representing the SFDT vehicle prior to deployment of the SIAD, and the other representing the nominal shape with the SIAD inflated. Both models were fabricated from solid metal, and therefore, the effects of the flexibility of the inflatable decelerator were not considered. The test conditions were chosen to match, as close as possible, the Mach number, Reynolds number, and motion dynamics expected for the SFDT vehicle in flight, both with the SIAD stowed and deployed. For SFDT models with the SIAD stowed, 12 shots were performed covering a Mach number range of 3.2 to 3.7. For models representing the deployed SIAD, 37 shots were performed over a Mach number range of 2.0 to 3.8. Pitch oscillation amplitudes covered a range from 0.7 to 20.6 degrees RMS. Portions of this report (data analysis approach, aerodynamic modeling, and resulting aerodynamic coefficients) were originally published as an internal LDSD Project report [1] in 2012. In addition, this report provides a description of the test design approach, the test facility, and experimental procedures. Estimated non-linear aerodynamic coefficients, including pitch damping, for both model configurations are reported, and the shot-by-shot trajectory measurements, plotted in comparison with calculated trajectories based on the derived non-linear aerodynamic coefficients, are provided as appendices. Since the completion of these tests, two full-scale SFDT flights have been successfully conducted: one in June 2014 [2, 3], and one in June 2015 [3].
    Keywords: Aerodynamics
    Type: NASA/TM-2017-219693 , ARC-E-DAA-TN47243
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    Estimates for the Aerodynamic Coefficients of Ringsail and Disk-Gap-Band Parachutes Operating on Mars (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Models are presented for the aerodynamic coefficients of Supersonic Ringsail and Disk-Gap-Band parachutes as functions of total porosity, Lambda(sub t), Mach number, M, and total angle of attack, Alpha(sub t) (when necessary). The source aerodynamic coefficients data used for creating these models were obtained from a wind tunnel test of subscale parachutes. In this wind tunnel test, subscale parachutes of both parachute types were fabricated from two different fabrics with very different permeabilities. By varying the fabric permeability, while maintaining the parachute geometry constant, it was possible to vary Alpha(sub t). The fabric permeability test data necessary for the calculation of Alpha(sub t) were obtained from samples of the same fabrics used to fabricate the subscale parachutes. Although the models for the aerodynamic coefficients are simple polynomial functions of Alpha(sub t) and M, they are capable of producing good reproductions of the source data. The (Alpha(sub t), M) domains over which these models are applicable are clearly defined. The models are applicable to flight operations on Mars.
    Keywords: Aerodynamics
    Type: NASA/TM-2017-219619 , L-20812 , NF1676L-27003
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    Status, Emerging Ideas and Future Directions of Turbulence Modeling Research in Aeronautics (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: In July 2017, a three-day Turbulence Modeling Symposium sponsored by the University of Michigan and NASA was held in Ann Arbor, Michigan. This meeting brought together nearly 90 experts from academia, government and industry, with good international participation, to discuss the state of the art in turbulence modeling, emerging ideas, and to wrestle with questions surrounding its future. Emphasis was placed on turbulence modeling in a predictive context in complex problems, rather than on turbulence theory or descriptive modeling. This report summarizes many of the questions, discussions, and conclusions from the symposium, and suggests immediate next steps.
    Keywords: Aerodynamics
    Type: NASA/TM-2017-219682 , L-20880 , NF1676L-28239
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    Wind Tunnel Investigation of Passive Porosity Applied to the Leading-Edge Extension and Leading-Edge Flaps on a Slender Wing at Subsonic Speed (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A wind tunnel experiment was conducted in the NASA Langley Research Center 7- by 10-Foot High Speed Tunnel to determine the effects of passive surface porosity on the subsonic vortex flow interactions about a general research fighter configuration. Flow-through porosity was applied to the leading-edge extension, or LEX, and leading-edge flaps mounted to a 65deg cropped delta wing model as a potential vortex flow control technique at high angles of attack. All combinations of porous and nonporous LEX and flaps were investigated. Wing upper surface static pressure distributions and six-component forces and moments were obtained at a free-stream Mach number of 0.20 corresponding to a Reynolds number of 1.35(106) per foot, angles of attack up to 45deg, angles of sideslip of 0deg and +/-5deg, and leading-edge flap deflections of 0deg and 30deg.
    Keywords: Aerodynamics
    Type: NASA-TM-2017-219596 , L-20784 , NF1676L-26349
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    Design Guide for Aerodynamics Testing of Earth and Planetary Entry Vehicles in a Ballistic Range (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The purpose of this manual is to aid in the design of an aerodynamics test of an earth or planetary entry capsule in a ballistic range. In this manual, much use is made of the results and experience gained in 50 years of ballistic range aerodynamics testing at the NASA Ames Research Center, and in particular, that gained in the last 27 years, while the author was working at NASA Ames. The topics treated herein include: Data to be obtained; flight data needed to design test; Reynolds number and dynamic similarity of flight trajectory and ballistic range test; capabilities of various ballistic ranges; Calculations of swerves due to average and oscillating lift and of drag-induced velocity decreases; Model and sabot design; materials, weights and stresses; Sabot separation; Launches at angle of attack and slapping with paper to produce pitch/yaw oscillations.
    Keywords: Aerodynamics
    Type: NASA/TM-2017-219473 , ARC-E-DAA-TN20974
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