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  • Meteorology and Climatology  (313)
  • Astronomy  (243)
  • Aerodynamics  (189)
  • ddc:330
  • 1995-1999  (778)
  • 1999  (778)
  • 1
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 2
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 3
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    Berlin : Birkhäuser | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2014-08-15
    Description: Ökoeffizienz ist die Grundlage eines zukunftsfähigen Managements, dessen Ziel es ist, Ökonomie und Ökologie zu vereinen. Ernst Ulrich von Weizsäcker und Jan-Dirk Seiler-Hausmann zeigen, daß diese Kombination den Unternehmen in Zukunft sogar mehr Gewinn bringen kann als herkömmliche Unternehmensführung.
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 4
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    Bonn : Bündnis 90/Die Grünen | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 5
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    Cheltenham : Elgar | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-04-30
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    Language: English
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  • 6
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    Wiesbaden : Gabler | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-04-30
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  • 7
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    Leipzig : Brockhaus | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2014-08-15
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 8
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    Salzburg : Eigenverl. | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 9
    Publication Date: 2020-10-13
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 10
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2014-08-15
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  • 11
    Publication Date: 2014-08-15
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 12
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    Berlin : Birkhäuser | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 13
    Publication Date: 2016-04-28
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 14
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-11-21
    Description: Statisticians avoid getting involved in data analysis, leaving data users on their own in interpreting the results of their work. This is particularly unfortunate in a new area of applied statistics such as environmental accounting with which few are really familiar. Earlier this year data producers and users explored, in a national seminar, possible policy applications of the results of a "green accounting" project in the Philippines. The main findings of the author's contribution to the seminar, on which the present paper is based, are that environmental accounts: (1) present evidence of sustainable economic performance in the country during the relatively short-time period of 1988–1994; (2) provide information for environmental cost internalization; (3) may guide investment to environmentally sound production processes; (4) help to specify and monitor policies of natural wealth conservation, distribution and management; and (5) reveal major data gaps. The paper concludes that environmental accounts help to assess the sustainability of economic growth in terms of broadly defined capital maintenance. The sustainability of development, however, would have to be measured by alternative or supplementary physical indicators linked to quantifiable standards or targets.
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 15
    Publication Date: 2018-04-30
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 16
    Publication Date: 2018-04-30
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 17
    Publication Date: 2018-04-30
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 18
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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  • 19
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    Cheltenham : Elgar | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
    Keywords: ddc:330
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  • 20
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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  • 21
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    Berlin : Birkhäuser | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-04-11
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 22
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 23
    Publication Date: 2016-04-28
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    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 24
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    Bad Neuenahr-Ahrweiler : Europ. Academy for the Study of Consequences of Scientific and Technological Advance | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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  • 25
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    München : Hampp | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2014-08-15
    Keywords: ddc:330
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    Language: German
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  • 26
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-04-30
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  • 27
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2016-04-28
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  • 28
    Publication Date: 2018-11-19
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 29
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    Gelsenkirchen : Inst. Arbeit und Technik | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2018-11-19
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  • 30
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2022-02-18
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 31
    Publication Date: 2022-02-18
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 32
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2022-02-18
    Keywords: ddc:330
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  • 33
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    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2022-02-18
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: German
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  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 34 (1999), S. 199-229 
    ISSN: 1572-9648
    Keywords: Aerodynamics ; Kutta condition ; Edge singularities ; Boundary integral equations ; Fluid dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This review paper presents a unified formulation of the Kutta condition for steady and unsteady flows, implemented by removing all unbounded velocity singularities (of power‐law and logarithmic type) at the trailing edge, and including nonlinear wakes and thick swept‐back wings. A suitable boundary integral approach is adopted and the uniqueness issue is discussed for several wing configurations of interest in aerodynamics. Sommario. Si presenta una formulazione unificata della condizione di Kutta per flussi stazionari e non stazionari, ottenuta imponendo la limitatezza della velocità al bordo d'uscita, e valida nel caso nonlineare anche per ali a freccia. Si utilizza un opportuno approccio integrale al contorno e si discute il problema dell'unicità per svariate configurazioni alari di interesse nelle applicazioni.
    Type of Medium: Electronic Resource
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  • 35
    Publication Date: 1999-02-19
    Description: Polycyclic aromatic hydrocarbons (PAHs) in water ice were exposed to ultraviolet (UV) radiation under astrophysical conditions, and the products were analyzed by infrared spectroscopy and mass spectrometry. Peripheral carbon atoms were oxidized, producing aromatic alcohols, ketones, and ethers, and reduced, producing partially hydrogenated aromatic hydrocarbons, molecules that account for the interstellar 3.4-micrometer emission feature. These classes of compounds are all present in carbonaceous meteorites. Hydrogen and deuterium atoms exchange readily between the PAHs and the ice, which may explain the deuterium enrichments found in certain meteoritic molecules. This work has important implications for extraterrestrial organics in biogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernstein, M P -- Sandford, S A -- Allamandola, L J -- Gillette, J S -- Clemett, S J -- Zare, R N -- New York, N.Y. -- Science. 1999 Feb 19;283(5405):1135-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA-Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000, USA. mbernstein@mail.arc.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10024233" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohols/chemistry ; Astronomical Phenomena ; Astronomy ; Deuterium/chemistry ; Ethers/chemistry ; *Evolution, Chemical ; *Exobiology ; Hydrogen/chemistry ; *Ice ; Mass Spectrometry ; Meteoroids ; Origin of Life ; Oxidation-Reduction ; Photolysis ; Polycyclic Hydrocarbons, Aromatic/*chemistry ; Quinones/chemistry ; Spectrophotometry, Infrared ; *Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 36
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-12-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hogg, D W -- New York, N.Y. -- Science. 1999 Nov 26;286(5445):1679.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10610561" target="_blank"〉PubMed〈/a〉
    Keywords: Astronomical Phenomena ; Astronomy ; *Biological Evolution ; Selection, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 37
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-03-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ehrenfreund, P -- New York, N.Y. -- Science. 1999 Feb 19;283(5405):1123-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Austrian Academy of Sciences and at Leiden Observatory, Leiden, The Netherlands. pascale@strw.leidenuniv.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10075570" target="_blank"〉PubMed〈/a〉
    Keywords: Astronomical Phenomena ; Astronomy ; *Cosmic Dust ; Deuterium/chemistry ; Earth (Planet) ; *Evolution, Chemical ; *Exobiology ; Hydrogen/chemistry ; Ice ; Meteoroids ; Origin of Life ; Polycyclic Hydrocarbons, Aromatic/*chemistry ; Ultraviolet Rays
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 38
    Publication Date: 2011-09-13
    Description: This report summarizes the technical parameters and the technical staff of the VLBI system at GGAO. It also gives an overview of VLBI activities during the previous year. The outlook lists the tasks planned for 1999.
    Keywords: Astronomy
    Type: International VLBI Service for Geodesy and Astrometry: 1999 Annual Report; 46-48; NASA/TP-1999-209243
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  • 39
    Publication Date: 2004-12-03
    Description: The work to be described was performed at the NASA Langley UPWT (4-ft supersonic), test section #2, during 21-24 May 1996. The configuration being tested was the 1.675% Ref H controls model; test conditions were Ma = 2.40, Re = 3 million/ft. This was an exploration of a new technique, and it was not intended to provide definitive comparison of measured and computed skin friction results. It is, however, hoped that the experience gained will make such a rigorous comparison possible in the future.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance; Volume 1; Part 2; 1478-1499; NASA/CP-1999-209691/VOL1/PT2
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  • 40
    Publication Date: 2004-12-03
    Description: To summarize the significant highlights in this report: (1) Data quality, determined by multiple repeat runs performed on the TCA baseline configuration, and long-term repeatability, determined by comparing baseline Reference H data from this test to a previous test, have been shown to be good. (2) The longitudinal stability of the TCA is more non-linear than for the Reference H, and while it is similar at normal lift values, the TCA has considerably more pitch-up at higher lift. (3) Longitudinal control effectiveness of the TCA is similar to the Reference H and the ratio of elevator effectiveness to horizontal tail effectiveness is approximately 0.3. 4) The directional stability of the TCA is improved relative to Reference H at higher angles-of attack. The chine is effective for improving directional stability. (5) The directional control effectiveness 'of the TCA rudder is the same as that of the Reference H rudder at low angles-of-attack, after taking factors, such as number of rudder panels deflected and vertical tail volume into account. However, rudder effectiveness was shown to be reduced at higher angles-of-attack. (6) The lateral stability was shown to be reduced relative to the Reference H, which may be beneficial at low speeds for alleviating lateral control saturation. (7) Lateral control effectiveness for the TCA was shown to be similar to the Reference H for negative trailing-edge flap deflections and was reduced by approximately 25% for positive trailing-edge flap deflections.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 612-668; NASA/CP-1999-209691/VOL1/PT1
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  • 41
    Publication Date: 2004-12-03
    Description: This paper gives the results of a grid study, a turbulence model study, and a Reynolds number effect study for transonic flows over a high-speed aircraft using the thin-layer, upwind, Navier-Stokes CFL3D code. The four turbulence models evaluated are the algebraic Baldwin-Lomax model with the Degani-Schiff modifications, the one-equation Baldwin-Barth model, the one-equation Spalart-Allmaras model, and Menter's two-equation Shear-Stress-Transport (SST) model. The flow conditions, which correspond to tests performed in the NASA Langley National Transonic Facility (NTF), are a Mach number of 0.90 and a Reynolds number of 30 million based on chord for a range of angle-of-attacks (1 degree to 10 degrees). For the Reynolds number effect study, Reynolds numbers of 10 and 80 million based on chord were also evaluated. Computed forces and surface pressures compare reasonably well with the experimental data for all four of the turbulence models. The Baldwin-Lomax model with the Degani-Schiff modifications and the one-equation Baldwin-Barth model show the best agreement with experiment overall. The Reynolds number effects are evaluated using the Baldwin-Lomax with the Degani-Schiff modifications and the Baldwin-Barth turbulence models. Five angles-of-attack were evaluated for the Reynolds number effect study at three different Reynolds numbers. More work is needed to determine the ability of CFL3D to accurately predict Reynolds number effects.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1185-1214; NASA/CP-1999-209690/PT3
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  • 42
    Publication Date: 2004-12-03
    Description: The NASA High Speed Research (HSR) Program is intended to establish a technology base enabling industry development of an economically viable and environmentally acceptable second generation high speed civil transport (HSCT). The HSR program consists of work directed towards several broad technology areas, one of which is aerodynamic performance. The objective of the Configuration Aerodynamics task of the Aerodynamic Performance technology area is the development of aerodynamic drag reduction, stability and control, and propulsion airframe integration technologies required to support the HSCT development process. Towards this goal, computational and empirical based aerodynamic design tools are being developed, evaluated, and validated through ground based experimental testing. In addition, methods for ground to flight scaling are being developed and refined. Successful development of validated design and scaling methodologies will result in improved economy of operation for an HSCT and reduce uncertainty in full-scale flight predictions throughout the development process.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 539-569; NASA/CP-1999-209692/VOL1/PT1
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  • 43
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    In:  CASI
    Publication Date: 2004-12-03
    Description: It is not unusual when comparing CFD data to experimental data to find discrepancies between the results. Sometimes forces and moments compare well, while surface pressures do not, and vice versa. It is commonplace for the researcher to believe that the flow field has been accurately simulated when these types of measurements compare well. However, being able to routinely predict boundary layer transition and separated flows are not guaranteed. In fact accurate simulation of these types of flow physics has been a challenge to the CFD community. In order to improve Navier-Stokes predictions for complex vortical flow fields, more detailed information about the flow physics is necessary. Unfortunately, the many wind-tunnel tests performed in Langley's NTF and 14x22 facilities as well as in the Ames' 12 ft. Tunnel provided little information about the detailed flow physics, and no priority was given to obtaining any CFD measurements. Using the latest experimental techniques, this information can and should be obtained for present and future use.
    Keywords: Aerodynamics
    Type: 1999 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 2; Part 2; 913-948; NASA/CP-1999-209704/VOL2/PT2
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  • 44
    Publication Date: 2004-12-03
    Description: Thunderstorms separate charge. Most places they lift positive charge or lower negative, a few places they lift negative or lower positive. The electrical generator is stronger in some parts of the cloud than in others. Our long term goal is to map this generator. Cloud physicists tell us that uncharged ice and water particles become charged by collision, and that the charge transferred depends on size, temperature and humidity. There is still some disagreement about exactly how the charge transferred depends on size, temperature, and humidity. In principle, if we knew this ice physics, and also knew the distribution of particles everywhere in the storm, and the winds everywhere and the temperature and humidity everywhere, then we could compute everywhere the electrical power of the thunderstorm generator. In practice it is difficult to know all these things, particularly the distribution of particles, so it is difficult to use real thunderstorms to falsify cloud electrification theories. We here take one small step towards computing that map of electrical generator power, by relating radar reflectivity profiles of 2000 storms to lightning flash rates of those storms. This small step by itself doesn't falsify any existing electrification theories; it merely places weak constraints on the relation of electric generator power to cloud ice.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 719-721; NASA/CP-1999-209261
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  • 45
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2004-12-03
    Description: Two primary detection techniques (optical and RF) have a proven capability for detecting lightning from low earth orbit. However, the lightning processes that generate the optical and RF signals are vastly different providing significantly different information content from each sensor type. Because of the intervening ionosphere, low frequency RF components do not reach satellite altitudes. As a consequence, many of the processes associated with the major energy release of a lightning event (i.e. return strokes, k-changes, recoil streamers, etc), in all likelihood contribute little to the RF signal arriving at the satellite. The optical output from lighting, on the other hand, has been shown to be highly correlated with the energetic, charge-transferring processes mentioned above. On the down side, the optical energy, while essentially unaffected by the atmosphere once it emerges from the cloud, is heavily scattered within the cloud. While there is little absorption by the cloud, the great optical depth makes the total light energy emerging from the cloud to be dependent on where in the cloud the lightning occurred. Analyses suggest that when lightning is confined to the lowest regions of the cloud, the light is strongly attenuated and detection becomes problematic. Fortunately, the vast majority of lightning flashes are comprised of channels that propagate through the middle of the cloud and higher. These flashes produce bright signals at the top of a cloud and are readily detectable. Presently, we have two optical instruments in orbit. The Optical Transient Detector (OTD) has been orbiting the earth since April, 1995, while the Lightning Imaging Sensor (LIS) was launched on the Tropical Rainfall Measuring Mission (TRMM) in November of 1997. Both instruments are relatively small, solid state optical imagers, designed specifically to detect and locate lightning activity from low earth orbit with high detection efficiency and location accuracy.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 715-718; NASA/CP-1999-209261
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  • 46
    Publication Date: 2004-12-03
    Description: For the past century, scientists have made quantitative measurements of lightning discharges. In the process, they refined the definition of a lightning unit, or basic quantum of lightning, in order to base it on observable parameters. In this paper, we will use cluster analysis to derive a basic spatial and temporal definition or scale length for the unit of lightning. We will use data from three different systems that detected pulses from the same storm complex over Central Oklahoma during June, 1998. Since the different instruments detect lightning in different ways with different resolutions, there may not be a single definition of the unit of lightning that can be applied to all three systems. However, common components can be found since all instrumentation are detecting aspects of the same phenomenon.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 166-169; NASA/CP-1999-209261
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  • 47
    Publication Date: 2004-12-03
    Description: This paper focuses on the parallel computation of aerodynamic derivatives via automatic differentiation of the Euler/Navier-Stokes solver CFL3D. The comparison with derivatives obtained by finite differences is presented and the scaling of the time required to obtain the derivatives relative to the number of processors employed for the computation is shown. Finally, the derivative computations are coupled with an optimizer and surface/volume grid deformation tools to perform an optimization to reduce the drag of a three-dimensional wing.
    Keywords: Aerodynamics
    Type: HPCCP/CAS Workshop Proceedings 1998; 219-224; NASA/CP-1999-208757
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  • 48
    Publication Date: 2004-12-03
    Description: Current parallel computational approaches involve distributed and shared memory paradigms. In the distributed memory paradigm, each processor has its own independent memory. Message passing typically uses a function library such as MPI or PVM. In the shared memory paradigm, such as that used on the SGI Origin 2000 machine, compiler directives are used to instruct the compiler to schedule multiple threads to perform calculations. In this paradigm, it must be assured that processors (threads) do not simultaneously access regions of memory in such away that errors would occur. This paper utilizes the latest version of the SGI MPI function library to combine the two parallelization paradigms to perform aerodynamic shape optimization of a generic wing/body.
    Keywords: Aerodynamics
    Type: HPCCP/CAS Workshop Proceedings 1998; 207-212; NASA/CP-1999-208757
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  • 49
    Publication Date: 2004-12-03
    Description: The primary objectives of this study were to expand the data base showing the effects of LE radius distribution and corresponding sensitivity to Rn at subsonic and transonic conditions, and to assess the predictive capability of CFD for these effects. Several key elements led to the initiation of this project: 1) the necessity of meeting multipoint design requirements to enable a viable HSCT, 2) the demonstration that blunt supersonic leading-edges can be associated with performance gain at supersonic speeds , and 3) limited data. A test of a modified Reference H model with the TCA planform and 2 LE radius distributions was performed in the NTF, in addition to Navier-Stokes analysis for an additional 3 LE radius distributions. Results indicate that there is a tremendous potential to improve high-lift performance through the use of a blunt LE across the span given an integrated, fully optimized design, and that low Rn data alone is probably not sufficient to demonstrate the benefit.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 588-611; NASA/CP-1999-209691/VOL1/PT1
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  • 50
    Publication Date: 2004-12-03
    Description: This paper presents results of a study which attempted to provide some understanding of the relationship between skin friction drag estimates produced by flat plate methods and those produced by Navier-Stokes computations. A brief introduction is followed by analysis, including a flat plate grid study, analysis of the wing flow, an analysis of the fuselage flow. Other results of interest are then presented, including turbulence model sensitivities, and brief analysis of other configurations.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance; Volume 1; Part 2; 1452-1477; NASA/CP-1999-209691/VOL1/PT2
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  • 51
    Publication Date: 2004-12-03
    Description: Efforts towards understanding boundary layer transition characteristics on a High Speed Civil Transport (HSCT)-class configuration in the National Transonic Facility (NTF) are ongoing. The majority of the High Speed Research (HSR) data base in the NTF has free transition on the wing, even at low Reynolds numbers (Rn) attainable in conventional facilities. Limited data has been obtained and is described herein showing the effects of a conventional, Braslow method based wing boundary-layer trip on drag. Comparisons are made using force data polars and surface flow visualization at selected angles-of-attack and Mach number. Minimum drag data obtained in this study suggest that boundary layer transition occurred very near the wing leading edge by a chord Rn of 30 million. Sublimating chemicals were used in the air mode of operation only at low Rn and low angles-of-attack with no flap deflections; sublimation results suggest that the forebody and outboard wing panel are the only regions with significant laminar flow. The process and issues related to the sublimating chemical technique as applied in the NTF are discussed. Beyond the existing experience, status of efforts to develop a production transition detection system applicable to both air and cryogenic nitrogen environments is presented.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 579-596; NASA/CP-1999-209690/PT2
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  • 52
    Publication Date: 2004-12-03
    Description: Model deformation measurement techniques have been investigated and developed at NASA's Langley Research Center. The current technique is based upon a single video camera photogrammetric determination of two dimensional coordinates of wing targets with a fixed (and known) third dimensional coordinate, namely the spanwise location. Variations of this technique have been used to measure wing twist and bending at a few selected spanwise locations near the wing tip on HSR models at the National Transonic Facility, the Transonic Dynamics Tunnel, and the Unitary Plan Wind Tunnel. Automated measurements have been made at both the Transonic Dynamics Tunnel and at Unitary Plan Wind Tunnel during the past year. Automated measurements were made for the first time at the NTF during the recently completed HSR Reference H Test 78 in early 1996. A major problem in automation for the NTF has been the need for high contrast targets which do not exceed the stringent surface finish requirements. The advantages and limitations (including targeting) of the technique as well as the rationale for selection of this particular technique are discussed. Wing twist examples from the HSR Reference H model are presented to illustrate the run-to-run and test-to-test repeatability of the technique in air mode at the NTF. Examples of wing twist in cryogenic nitrogen mode at the NTF are also presented.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 561-578; NASA/CP-1999-209690/PT2
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  • 53
    Publication Date: 2004-12-03
    Description: To develop full scale flight performance predictions an understanding of Reynolds number effects on HSCT-class configurations is essential. A wind tunnel database utilizing a 2.2% scale Reference H model in NASA Langley Research Centers National Transonic Facility is being developed to assess these Reynolds number effects. In developing this database temperature and aeroelastic corrections to the wind tunnel data have been identified and are being analyzed. Once final corrections have been developed and applied, then pure Reynolds number effects can be determined. In addition, final corrections will yield the data required for CFD validation at q = 0. Presented in this report are the results of seven tests involving the wing/body configuration. This includes summaries of data acquired in these tests, uncorrected Reynolds number effects, and temperature and aeroelastic corrections. The data presented herein illustrates the successes achieved to date as well as the challenges that will be faced in obtaining full scale flight performance predictions.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1073-1107; NASA/CP-1999-209690/PT3
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  • 54
    Publication Date: 2004-12-03
    Description: Experience with afterbody closure effects and accompanying test techniques issues on a High Speed Civil Transport (HSCT)-class configuration is described. An experimental data base has been developed which includes force, moment, and surface pressure data for the High Speed Research (HSR) Reference H configuration with a closed afterbody at subsonic and transonic speeds, and with a cylindrical afterbody at transonic and supersonic speeds. A supporting computational study has been performed using the USM3D unstructured Euler solver for the purposes of computational fluid dynamics (CFD) method assessment and model support system interference assessment with a focus on lower blade mount effects on longitudinal data at transonic speeds. Test technique issues related to a lower blade sting mount strategy are described based on experience in the National Transonic Facility (NTF). The assessment and application of the USM3D code to the afterbody/sting interference problem is discussed. Finally, status and plans to address critical test technique issues and for continuation of the computational study are presented.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 529-560; NASA/CP-1999-209690/PT2
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  • 55
    Publication Date: 2004-12-03
    Description: The Boeing Reference H configuration was tested in the NASA Ames 9x7 Supersonic Wind Tunnel. A simulated unstarted inlet was evaluated as well as the aerodynamic performance of the configuration with and without nacelle and diverter components. These experimental results were compared with computational results from the unstructured grid Euler flow solver AIRPLANE. The comparisons between computational and experimental results were good, and demonstrated that the Euler code is capable of efficiently and accurately predicting the changes in the aerodynamic coefficients associated with inlet unstart and the effects of the nacelle and diverter components.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1285-1325; NASA/CP-1999-209690/PT3
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  • 56
    Publication Date: 2004-12-03
    Description: This presentation will describe the organization and conduct of the workshops, list the topics discussed, and conclude with a more-detailed examination of a related set of issues dear to the presenters heart. Because the current HSCT configuration is expected to have (mostly) turbulent flow over the wings, and because current CFD predictions assume fully-turbulent flow, the wind tunnel testing to date has attempted to duplicate this condition at the lower Reynolds numbers attainable on the ground. This frequently requires some form of artificial boundary layer trip to induce transition near the wing's leading edge. But this innocent-sounding goal leads to a number of complications, and it is not clear that present-day testing technology is adequate to the task. An description of some of the difficulties, and work underway to address them, forms the "Results" section of this talk. Additional results of the testing workshop will be covered in presentations by other team members.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 515-537; NASA/CP-1999-209692/VOL1/PT1
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  • 57
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2004-12-03
    Description: This paper presents The Propulsion Airframe Integration Advisory report in viewgraph form. The approach of the advisory group is to identify and prioritize technology elements (1.0 Inlet Issues, 2.0 Nozzle Issues, 3.0 Nacelle Design, and 4.0 Airframe Integration).
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 31-39; NASA/CP-1999-209692/VOL1/PT1
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  • 58
    Publication Date: 2004-12-03
    Description: Preliminary human acceptability studies of sonic booms indicate that supersonic flight is unlikely to be acceptable even at noise levels significantly below 1994 low boom designs (reference 1, p. 288). Further, these low boom designs represent considerable changes to baseline configurations, and changes translate into additional effort and uncertain structural weight penalties that may provide no annoyance benefit, increasing the risk of including low boom technology. Since over land sonic boom designs were so risky (and yet the acceptability studies highlight how annoying sonic booms are), boom softening studies were undertaken to reduce the boom of baseline configurations using minor modifications that would not significantly change the designs. The goal of this work is to reduce boom levels over water. Even though Concorde over water boom has not been found to have any adverse environmental impact, boom levels for baseline HSCT designs are 50% higher in overpressure than the Concorde (due to a doubling in configuration weight with only a 50% increase in length),
    Keywords: Aerodynamics
    Type: 1995 NASA High-Speed Research Program Sonic Boom Workshop; Volume 2; 162-174; NASA/CP-1999-209520/VOL2
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  • 59
    Publication Date: 2004-12-03
    Description: Officially, the Tu-144 was the first supersonic-cruise, passenger-carrying aircraft to enter commercial service. Design, construction, and testing were carried out by the Soviet Union, flight certification was by the Soviet Union, and the only regular passenger flights were scheduled and flown across the territory of the Soviet Union. Although it was not introduced to international passenger service, there were many significant engineering accomplishments achieved in the design, production, and flight of this aircraft. Development of the aircraft began with a prototype stage. Systematic testing and redesign led to a production aircraft in discrete stages that measurably improved the performance of the aircraft from the starting concept to final aircraft certification. It flew in competition with the English-French Concorde for a short time, but was withdrawn from national commercial service due to a lack of interest by airlines outside the Soviet Union. NASA became interested in the Tu- 144 aircraft when it was offered for use as a flying "testbed" in the study of operating characteristics of a supersonic-cruise commercial airplane. Since it had been in supersonic-cruise service, the Tu- 144 had operational characteris'tics similar to those anticipated in the conceptual aircraft designs being studied by the United States aircraft companies. In addition to the other operational tests being conducted on the Tu-144 aircraft, it was proposed that two sets of sonic-boom pressure signature measurements be made. The first set would be made on the ground, using techniques and devices similar to those in reference I and many other subsequent studies. A second set would be made in the air with an instrumented aircraft flying close under the Tu-144 in supersonic flight. Such in-flight measurements would require pressure gages that were capable of accurately recording the flow-field overpressures generated by the Tu- 144 at relatively close distances under the vehicle. Therefore, an analysis of the Tu-144 was made to obtain predictions of pressure signature shape and shock strengths at cruise conditions so that the range and characteristics of the required pressure gages could be determined well in advance of the tests. Cancellation of the sonic-boom signature measurement part of the tests removed the need for these pressure gages. Since CFD methods would be used to analyze the aerodynamic performance of the Tu-144 and make similar pressure signature predictions, the relatively quick and simple Whitham-theory pressure signature predictions presented in this paper could be used for comparisons. Pressure signature predictions of sonic-boom disturbances from the Tu- 144 aircraft were obtained from geometry derived from a three-view description of the production aircraft. The geometry was used to calculate aerodynamic performance characteristics at supersonic-cruise conditions. These characteristics and Whitham/Walkden sonic-boom theory were employed to obtain F-functions and flow-field pressure signature predictions at a Mach number of 2.2, at a cruise altitude of 61000 feet, and at a cruise weight of 350000 pounds.
    Keywords: Aerodynamics
    Type: 1995 NASA High-Speed Research Program Sonic Boom Workshop; Volume 2; 1-16; NASA/CP-1999-209520/VOL2
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  • 60
    Publication Date: 2004-12-03
    Description: This document contains the details of the thermal analysis of the X-38 aft fin during re-entry. This analysis was performed in order to calculate temperature response of the aft fin components. This would be provided as input to a structural analysis and would also define the operating environment for the electromechanical actuator (EMA). The calculated structural temperature response would verify the performance of the thermal protection system (TPS). The geometric representation of the aft fin was derived from an I-DEAS finite element model that was used for structural analysis. The thermal mass network model was derived from the geometric representation.
    Keywords: Aerodynamics
    Type: Ninth Thermal and Fluids Analysis Workshop Proceedings; 91-106; NASA/CP-1999-208695
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  • 61
    Publication Date: 2004-12-03
    Description: Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.
    Keywords: Meteorology and Climatology
    Type: Tenth Biennial Coherent Laser Radar Technology and Applications Conference; 68-71; NASA/CP-1999-209758
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  • 62
    Publication Date: 2004-12-03
    Description: Severe storms often have high flash rates (in excess of one flash per second) and are dominated by intracloud lightning activity. In addition to the extraordinary flash rates, there is a second distinguishing lightning characteristic of severe storms that seems to be important. When the total lightning history is examined, one finds sudden increases in the lightning rate, which we refer to as lightning "jumps," that precede the occurrence of severe weather by ten or more minutes. These jumps are typically 30-60 flashes/min, and are easily identified as anomalously large derivatives in the flash rate. This relationship is associated with updraft intensification and updraft strength is an important factor in storm severity (through the accumulation of condensate aloft and the stretching of vorticity). In several cases, evidence for diminishment of midlevel rotation and the descent of angular momentum from aloft is present prior to the appearance of the surface tornado. Based on our experience with severe and tornadic storms in Central Florida, we believe the total lightning may augment the more traditional use of NEXRAD radars and storm spotters. However, a more rigorous relation of these jumps to storm kinematics is needed if we are to apply total lightning in a decision tree that leads to improved warning lead times and decreased false alarm rates.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 515-518; NASA/CP-1999-209261
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  • 63
    Publication Date: 2004-12-03
    Description: The Lightning Imaging Sensor (LIS) is a NASA Earth Observing System (EOS) instrument on the Tropical Rainfall Measuring Mission (TRMM) platform designed to acquire and investigate the distribution and variability of total lightning (i.e., cloud-to-ground and intracloud) between q35' in latitude. Since lightning is one of the responses of the atmosphere to thermodynamic and dynamic forcing, the LIS data is being used to detect deep convection without land-ocean bias, estimate the precipitation mass in the mixed phased region of thunderclouds, and differentiate storms with strong updrafts from those with weak vertical motion.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 746-749; NASA/CP-1999-209261
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  • 64
    Publication Date: 2004-12-03
    Description: The Optical Transient Detector (OTD) is a space-based instrument specifically designed to detect and locate lightning discharges (intracloud and cloud-to-ground) as it orbits the Earth. A statistical examination of OTD lightning data reveals that nearly 1.2 billion flashes occurred over the entire earth during the one year period from September 1995 through August 1996. This translates to an average of 37 lightning flashes occurring around the globe every second, which is well below the traditional estimate of 100 flashes per second. An average of 75% of the global lightning activity during the year occurs between 30' S and 30' N. An analysis of the annual lightning distribution reveals that an average of 82% of the lightning flashes occur over the continents and 18% over the oceans, which translates to an average land-ocean flash density ratio of nearly 11.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 726-729; NASA/CP-1999-209261
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  • 65
    Publication Date: 2004-12-03
    Description: The lightning frequency model developed by Baker, Christian and Latham (1995) has been refined and extended, in an effort to provide a more realistic framework from which to examine computationally the relationships that might exist between lightning frequency f (which is now being routinely measured from satellites, using NASA/MSFC devices) and a variety of cloud physical parameters, including precipitation rate, updraught speed and non-precipitating ice content. Model results indicate the existence of a simple relationship between lightning frequency f and the upward flux of ice crystals into the thunderstorm anvil. It follows that, for a particular situation, one can assign a specific mass of non-precipitating ice to an individual lightning stroke. Therefore it may prove possible - using satellite measurements of global lightning - to estimate the atmospheric loading of ice crystals in thunderstorm anvils: a parameter of climatological importance. Early results from this work are presented, together with further studies of the relationships between f and other thundercloud parameters.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 363-366; NASA/CP-1999-209261
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  • 66
    Publication Date: 2004-12-03
    Description: A charge transfer process during the collision of a riming graupel pellet and an ice-crystal at low temperature is proposed. During riming, the surface structure of graupel deviates from perfect crystalline structure. A concept of quasi-solid layer (QSL) formation on the surface is introduced. This QSL contains defects formed during riming. In absence of impurities, positively charged X-defect abundance is considered in the outer layer. These defects are assumed to be the charge carriers during the charge transfer process. Some part of the QSL is stripped off by the colliding ice crystals, which thereby gain some positive charge, leaving the graupel pellet negatively charged. With the proposed model, fC to pC of charge transfer is observed per collision. A transition temperature between -10 C to -15 C is also noted beyond which the QSL concept does not hold. This transition temperature is dependent on the bulk liquid water content of the cloud.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 296-299; NASA/CP-1999-209261
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  • 67
    Publication Date: 2004-12-03
    Description: It is well known that most tropical cyclones (TCs) that make landfall along the Gulf coast of the United States spawn at least a few tornadoes. Although most landfalling TCs generate fewer than a dozen such tornadoes, a small proportion produce large swarm outbreaks, with as many as 25 or more tornadoes. Usually, these major outbreaks occur in large, intense hurricane-strength TCs, but on 15-17 August 1994 Tropical Storm Beryl spun off 37 tornadoes along its path from the Florida panhandle through the mid-Atlantic states. Some 32 of these tornadoes occurred on 16 August 1994 from eastern Georgia to southern Virginia, with most of these taking place in South Carolina. Beryl's 37 tornadoes moved it into what was at that time fifth place historically in terms of TC tornado productivity. The Beryl outbreak is especially noteworthy in that at least three of the tornadoes achieved peak intensity of F3 on the Fujita damage intensity scale. Although no fatalities resulted from the Beryl outbreak, at least 50 persons suffered injuries, and property damages totalled more than $50 million . The Beryl outbreak is a good example of a TC whose greatest danger to the public is its post-landfall severe weather. In this respect, and in the character of its swarm outbreak of tornadoes, it resembles another large tornado outbreak spawned by a relatively weak TC, Hurricane Danny of 1985). In the Danny outbreak, numerous shallow mini-supercell storms were found to have occurred, and it was noted that, because of the storms' relatively shallow depth, cloud-to-ground (CG) lightning was negligible. Better observations of future TC tornado outbreaks, especially with modern surveillance tools such as Doppler radars and the National Lightning Detection Network (NLDN), were recommended. Although the Beryl tornado outbreak is not the first set of TC-spawned tornado storms to be observed with the NLDN, it is one of the largest and likely the most intense such outbreak. The purpose of this paper is to document the NLDN-derived CG lightning characteristics of Beryl's tornadic storms, and to see how they compare with observations of CG lightning activity in other types of severe storms. In particular, we attempt to quantify the CG flash rates of TC tornadic cells, and to discover if there are any characteristics of their CG activity that may be useful to operational forecasters seeking to distinguish which cells are most likely to produce severe weather.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 511-514; NASA/CP-1999-209261
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  • 68
    Publication Date: 2004-12-03
    Description: The problem of retrieving ligntning, ground-strike location on a spherical Earth surface using a network of 4 or more time-of-arrival (TOA) sensors is considered, It is shown that this problem has an analytic solution and therefore does not require the use of nonlinear estimation theory (e.g., minimization). The mathematical robustness of the analytic solution is tested using computer-generated lightning sources and simulated TOA measurement errors. A summary of a quasi-analytic extension of the spherical Earth solution to an oblate spheroid Earth geometry is also provided.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 192-195; NASA/CP-1999-209261
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  • 69
    Publication Date: 2004-12-03
    Description: This study summarizes the results of an analysis of data from the LIS instrument on the TRMM platform. The data for the Indian summer monsoon season is examined to study the seasonal patterns of the geographic and diurnal distribution of lightning storms. The storms on the Tibetan plateau show a single large diurnal peak at about 1400 local solar time. A region of Northern Pakistan has two storm peaks at 0200 and 1400 local solar time. The morning peak is half the magnitude of the afternoon peak. The region south of the Himalayan Mountains has a combined diurnal cycle in location and time of storm occurrence.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 420-423; NASA/CP-1999-209261
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  • 70
    Publication Date: 2004-12-03
    Description: We have developed a new set of eight electric field mills that were flown on a NASA ER-2 high-altitude aircraft. During the Third Convection And Moisture EXperiment (CAMEX-3; Fall, 1998), measurements of electric field, storm dynamics, and ice microphysics were made over several hurricanes. Concurrently, the TExas-FLorida UNderflights (TEFLUN) program was being conducted to make the same measurements over Gulf Coast thunderstorms. Sample measurements are shown: typical flight altitude is 20km. Our new mills have an internal 16-bit A/D, with a resolution of 0.25V/m per bit at high gain, with a noise level less than the least significant bit. A second, lower gain channel gives us the ability to measure fields as high as 150 kV/m.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 527-529; NASA/CP-1999-209261
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  • 71
    Publication Date: 2004-12-03
    Description: The mapping of the lightning optical pulses detected by the Lightning Imaging Sensor (LIS) is compared with the radiation sources by Lightning Detection and Ranging (LDAR) and the National Lightning Detection Network (NLDN) for three thunderstorms observed during and overpasses on 15 August 1998. The comparison involves 122 flashes including 42 ground and 80 cloud flashes. For ground flash, the LIS recorded the subsequent strokes and changes inside the cloud. For cloud flashes, LIS recorded those with higher sources in altitude and larger number of sources. The discrepancies between the LIS and LDAR flash locations are about 4.3 km for cloud flashes and 12.2 km for ground flashes. The reason for these differences remain a mystery.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 738-741; NASA/CP-1999-209261
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  • 72
    Publication Date: 2004-12-03
    Description: Since April 1995, lightning activity around the globe has been monitored with the Optical Transient Detector (OTD). The OTD observations acquired during the one year period from September 1995 through August 1996 have been used to statistically determine the number of flashes that occur over the Earth during each hour of the diurnal cycle, expressed both as a function of local time and universal time. The globally averaged local [il,htnina activity displays a peak in late afternoon (1500-1800 local time) and a minimum in the morning hours (0600- 1000 local time) consistent with convection associated with diurnal heating. No diurnal variation is found for oceanic storms. The diurnal lightning distribution (universal time) for the globe displays a variation of about 35% about its mean as compared to the Carnegie curve which has a variation of only 15% above and below the mean.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 742-745; NASA/CP-1999-209261
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  • 73
    Publication Date: 2004-12-03
    Description: Total lightning observations made by the Optical Transient Detector (OTD) of a tornadic thunderstorm that occurred over Oklahoma on 17 April 1995 are presented. The average flash rate of the tornadic storm during the 3.2 min observation period was 45 flashes/min, with a flash rate density of 1.16 x 10(exp -4)/s sq km. The total flash rate was almost 18 times higher than the cloud-to-ground rate measured by the National Lightning Detection Network (NLDN). In addition, total lightning rates were observed to decrease prior to tornadic development.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 722-725; NASA/CP-1999-209261
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  • 74
    Publication Date: 2004-12-03
    Description: In recent years, atmospheric conductivity and electric field measurements over thunderstorms have been made at 20 km with a high altitude aircraft. After compensating for the effects of aircraft charging induced by external electric fields no significant variations in ambient conductivity above thunderstorms have been found. These Gerdien results contrast strongly with the large (and frequent) conductivity variations reported in studies using relaxation probe techniques.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 646-649; NASA/CP-1999-209261
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  • 75
    Publication Date: 2004-12-03
    Description: The El Nino Southern Oscillation (ENSO) is a climate anomaly responsible for world-wide weather impacts ranging from droughts to floods. In the United States, warm episode years are known to produce above normal rainfall along the Southeast US Gulf Coast and into the Gulf of Mexico, with the greatest response observed in the October-March period of the current warm-episode year. The 1997-98 warm episode, notable for being the strongest event since 1982-83, presents our first opportunity to examine the response to a major ENSO event and determine the variation of wintertime thunderstorm activity in this part of the world. Due to the recent launch of a lightning sensor on NASA's Tropical Rainfall Measuring Mission (TRMM) in November 1997 and the expanded coverage of the National Lightning Detection Network (NLDN), we are able to examine such year-to-year changes in lightning activity with far greater detail than ever before.
    Keywords: Meteorology and Climatology
    Type: 11th International Conference on Atmospheric Electricity; 519-522; NASA/CP-1999-209261
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  • 76
    Publication Date: 2004-12-03
    Description: To summarize the significant highlights in this report: (1) Data quality, determined by multiple repeat runs performed on the TCA baseline configuration, and long-term repeatability, determined by comparing baseline Reference H data from this test to a previous test, have been shown to be good. (2) The longitudinal stability of the TCA is more non-linear than for the Reference H, and while it is similar at normal lift values, the TCA has considerably more pitch-up at higher lift. (3) Longitudinal control effectiveness of the TCA is similar to the Reference H and the ratio of elevator effectiveness to horizontal tail effectiveness is approximately 0.3. (4) The directional stability of the TCA is improved relative to Reference H at higher angles-of attack. The chine is effective for improving directional stability.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 612-668; NASA/CP-1999-209691/VOL1/PT1
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  • 77
    Publication Date: 2004-12-03
    Description: The NASA-industry team has sponsored several studies in the last two years to address the installed nozzle boattail drag issues. Some early studies suggested that nozzle boattail drag could be as much as 25 to 40 percent of the subsonic cruise. As part of this study tests have been conducted at NASA-Langley to determine the uninstalled drag characteristics of a proposed nozzle. The overall objective was to determine the effects of nozzle external flap curvature and sidewall boattail variations. This test would also provide data for validating CFD predictions of nozzle boattail drag.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 669-706; NASA/CP-1999-209691/VOL1/PT1
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  • 78
    Publication Date: 2004-12-03
    Description: AIRPLANE (Jameson/Baker) is a steady inviscid unstructured Euler flow solver. It has been validated on many HSR geometries. It is implemented as MESHPLANE, an unstructured mesh generator, and FLOPLANE, an iterative flow solver. The surface description from an Intergraph CAD system goes into MESHPLANE as collections of polygonal curves to generate the 3D mesh. The flow solver uses a multistage time stepping scheme with residual averaging to approach steady state, but R is not time accurate. The flow solver was ported from Cray to IBM SP2 by Wu-Sun Cheng (IBM); it could only be run on 4 CPUs at a time because of memory limitations. Meshes for the four cases had about 655,000 points in the flow field, about 3.9 million tetrahedra, about 77,500 points on the surface. The flow solver took about 23 wall seconds per iteration when using 4 CPUs. It took about eight and a half wall hours to run 1,300 iterations at a time (the queue limit is 10 hours). A revised version of FLOPLANE (Thomas) was used on up to 64 CPUs to finish up some calculations at the end. We had to turn on more communication when using more processors to eliminate noise that was contaminating the flow field; this added about 50% to the elapsed wall time per iteration when using 64 CPUs. This study involved computing lift and drag for a wing/body/nacelle configuration at Mach 0.9 and 4 degrees pitch. Four cases were considered, corresponding to four nacelle mass flow conditions.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance; Volume 1; Part 2; 1605-1648; NASA/CP-1999-209691/VOL1/PT2
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  • 79
    Publication Date: 2004-12-03
    Description: The primary objectives of this study were to expand the data base showing the effects of LE radius distribution and corresponding . sensitivity to Rn at subsonic and transonic conditions, and to assess the predictive capability of CFD for these effects. Several key elements led to the initiation of this project: 1) the necessity of meeting multipoint design requirements to enable a viable HSCT, 2) the demonstration that blunt supersonic leading-edges can be associated with performance gain at supersonic speeds , and 3) limited data. A test of a modified Reference H model with the TCA planform and 2 LE radius distributions was performed in the NTF, in addition to Navier-Stokes analysis for an additional 3 LE radius distributions. Results indicate that there is a tremendous potential to improve high-lift performance through the use of a blunt LE across the span given an integrated, fully optimized design, and that low Rn data alone is probably not sufficient to demonstrate the benefit.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 588-610; NASA/CP-1999-209691/VOL1/PT1
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  • 80
    Publication Date: 2004-12-03
    Description: In cooperation with personnel from the Boeing ANP Laboratory and NASA Langley, a performance test was conducted using the Reference-H 1.675% model ("NASA Modular Model") without nacelles at the NASA Langley 16-Ft Transonic Tunnel. The main objective of the test was to determine the drag reduction achievable with leading-edge and trailing-edge flaps deflected along the outboard wing span at transonic Mach numbers (M = 0.9 to 1.2) for purpose of preliminary design and for comparison with computational predictions. The obtained drag data with flap deflections for Mach numbers of 1.07 to 1.20 are unique for the Reference H wing. Four leading-edge and two trailing-edge flap deflection angles were tested at a mean-wing chord-Reynolds number of about 5.7 million. An outboard-wing leading-edge flap deflection of 81 provides a 4.5 percent drag reduction at M = 1.2 A = 0.2), and much larger values at lower Mach numbers with larger flap deflections. The present results for the baseline (no flaps deflected) compare reasonably well with previous Boeing and NASA Ref-H tunnel tests, including high-Reynolds number NTF results. Viscous CFD simulations using the OVERFLOW thin-layer N.S. method properly predict the observed trend in drag reduction at M = 1.2 as function of leading-edge flap deflection. Modified linear theory properly predicts the flap effects on drag at subsonic conditions (Aero2S code), and properly predicts the absolute drag for the 40 and 80 leading-edge deflection at M = 1.2 (A389 code).
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1109-1141; NASA/CP-1999-209690/PT3
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  • 81
    Publication Date: 2004-12-03
    Description: Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a proposed high speed civil transport configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at Mach 2.4 for a range of angles-of-attack and sideslip. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex shock wave structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics are shown to correlate very well with the measured data across the examined range of angles-of-attack and sideslip. The results from the present effort have been documented into a NASA Controlled-Distribution report which is being presently reviewed for publication.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 287-308; NASA/CP-1999-209692/VOL1/PT1
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  • 82
    Publication Date: 2004-12-03
    Description: The objectives of the Cycle 2 Nonlinear Design Optimization Anlaytical Cross Checks are to: 1) Understand the variability in the predicted performance levels of the nonlinear designs arising from the use of different inviscid (full potential/Euler) and viscous (Navier-Stokes) analysis methods; and 2) Provide the information required to allow the performance levels of all three designs to be validated using the data from the NCV (nonlinear Cruise Validation) model test.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 45-73; NASA/CP-1999-209692/VOL1/PT1
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  • 83
    Publication Date: 2004-12-03
    Description: During the last cycle of concept design and wind-tunnel testing, the goal of the low-boom- shaped HSCT concepts (the B-935, the LB-16, and the LB- 1 8) was to meet mission requirements and generate shaped, ground-level pressure signatures with nose shock strengths of 1.0 psf or less. The wind-tunnel tests of these concepts produced results that were partially successful and encouraging although not fully up to expectations. In spite of this, however, these conceptual designs were overly optimistic and not acceptable because: the wing planforms had excessive area; the wing structural aspect ratio was too high; one concept had aft-fuselage rather than under-the-wing engines; and the gross takeoff weights were unrealistically low because of engines that were early, high-tech versions of later, revised, more-realistic engines. The need for reducing the ground-level overpressure shock strengths still existed; a need to be met within more restrictive guidelines of mission performance and gross takeoff weight limitations. Therefore, it was decided that the next conceptual design cycle would focus on decreased nose shock strengths, "boom softening," in the signatures of the Boeing and the McDonnell Douglas baseline concepts rather than low-boom concepts with shaped-signature designs. Overly-optimistic results were not the only problem with these low-sonic-boom concepts. Papers given at the 1994 Sonic-Boom Workshop had demonstrated that the problem of successful nacelle integration on HSCT concepts had only been partially solved. Wind-tunnel pressure signature data, from the HSCT-11B (a.k.a. the LB-18) wind-tunnel model, showed that the Langley HSCT design and analysis method had been successful in reducing the nacelle-volume disturbances in the flow field. This was due.to the engine nacelles mounted behind the wing trailing-edge on the aft fuselage so that no nacelle-wing interference-lift flow-field disturbances were generated. While acceptable from a sonic-boom research point of view, this concept was unacceptable from several practical and structural considerations. Preliminary wind-tunnel pressure signature data from the LB-16 wind-tunnel model, which had the engine nacelles mounted under the wings (the usual location), indicated that the application of the Langley nacelle-integration method had been only partially successful in the reduction of the nacelle-volume with nacelle-wing interference-lift pressure disturbances. So, "boom softening" had to also address the task of successful integration of the engine nacelles, with the engines in the required under-the-wing location. Unless this problem was solved, low-sonic-boom and low-drag modifications to the wing planform, the airfoil shape, and the fuselage longitudinal area distribution could be nullified if the nacelle disturbances added increments to the nose-shock strengths that were removed through component tailoring. In this paper, an arrow-wing boom-softened HSC7 concept which incorporated modifications to a baseline McDonnell Douglas concept is discussed. The analysis of the concept's characteristics will include estimates of weight, center of gravity, takeoff field length, mission range, and predictions of its ground-level sonic-boom pressure signature. Additional modifications which enhanced the softened-boom performance of this concept are also described as well as estimates of the performance penalties induced by these modifications.
    Keywords: Aerodynamics
    Type: 1995 NASA High-Speed Research Program Sonic Boom Workshop; Volume 2; 121-136; NASA/CP-1999-209520/VOL2
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  • 84
    Publication Date: 2004-12-03
    Description: A 1:300 scale wind-tunnel model of a conceptual High-Speed Civil Transport (HSCT) designed to generate a shaped, low-boom pressure signature on the ground was tested to obtain sonic-boom pressure signatures in the Langley Research Center Unitary Plan Wind Tunnel at a Mach number of 1.8 and a separation distance of about two body lengths or four wing-spans from the model. Two sets of engine nacelles representing two levels of engine technology were used on the model to determine the effects of increased nacelle volume. Pressure signatures were measured for (model lift)/(design lift) ratios of 0.5, 0.63, 0.75, and 1.0 so that the effect of lift on the pressure signature could be determined. The results of these tests were analyzed and used to discuss the agreement between experimental data and design expectations.
    Keywords: Aerodynamics
    Type: High-Speed Research: 1994 Sonic Boom Workshop. Configuration, Design, Analysis and Testing; 59-71; NASA/CP-1999-209699
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  • 85
    Publication Date: 2004-12-03
    Description: The NASA High Speed Research (HSR) Program is intended to establish a technology base enabling industry development of an economically viable and environmentally acceptable second generation high speed civil transport (HSCT). The objective of the Configuration Aerodynamics task of the program is the development of aerodynamic drag reduction, stability and control, and propulsion airframe integration technologies required to support the HSCT development process. Aerodynamic design tools are being developed, evaluated, and validated through ground based experimental testing. In addition, methods for ground to flight scaling are being developed and refined.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 147-169; NASA/CP-1999-209692/VOL1/PT1
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  • 86
    Publication Date: 2004-12-03
    Description: This paper reports on the model, test, and results from the Langley Supersonic Aftbody Closure wind tunnel test. This project is an experimental evaluation of the 1.5% Technology Concept Aircraft (TCA) aftbody closure model (Model 23) in the Langley Unitary Plan Wind Tunnel. The baseline TCA design is the result of a multidisciplinary, multipoint optimization process and was developed using linear design and analysis methods, supplemented with Euler and Navier-Stokes numerical methods. After a thorough design review, it was decided to use an upswept blade attached to the forebody as the mounting system. Structural concerns dictated that a wingtip support system would not be feasible. Only the aftbody part of the model is metric. The metric break was chosen to be at the fuselage station where prior aft-sting supported models had been truncated. Model 23 is thus a modified version of Model 20. The wing strongback, flap parts, and nacelles from Model 20 were used, whereas new aftbodies, a common forebody, and some new tails were fabricated. In summary, significant differences in longitudinal and direction stability and control characteristics between the ABF and ABB aftbody geometries were measured. Correcting the experimental data obtained for the TCA configuration with the flared aftbody to the representative of the baseline TCA closed aftbody will result in a significant reduction in longitudinal stability, a moderate reduction in stabilizer effectiveness and directional stability, and a moderate to significant reduction in rudder effectiveness. These reductions in the stability and control effectiveness levels of the baseline TCA closed aftbody are attributed to the reduction in carry-over area.
    Keywords: Aerodynamics
    Type: 1999 NASA High-Speed Research Performance Workshop; Volume 1; Part 2; 1365-1472; NASA/CP-1999-209704/VOL1/PT2
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  • 87
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2004-12-03
    Description: There were two objectives for this test. First, was to assess the reasons why there is approximately 1.5 drag counts (cts) discrepancy between measured and computed drag improvement of the Non-linear Cruise Validation (NCV) over the Technology Concept Airplane (TCA) wing body (WB) configurations. The Navier-Stokes (N-S) pre-test predictions from Boeing Commercial Airplane Group (BCAG) show 4.5 drag cts of improvement for NCV over TCA at a lift coefficient (CL) of 0. I at Mach 2.4. The pre-test predictions from Boeing Phantom Works - Long Beach, BPW-LB, show 3.75 drag cts of improvement. BCAG used OVERFLOW and BPW-LB used CFL3D. The first test entry to validate the improvement was held at the NASA Langley Research Center (LARC) UPV;T, test number 1687. The experimental results showed that the drag improvement was only 2.6 cts, not accounting for laminar run and trip drag. This is approximately 1.5 cts less than predicted computationally. In addition to the low Reynolds Number (RN) test, there was a high RN test in the Boeing Supersonic Wind Tunnel (BSWT) of NCV and TCA. BSV@T test 647 showed that the drag improvement of NCV over TCA was also 2.6 cts, but this did account for laminar run and trip drag. Every effort needed to be done to assess if the improvement measured in LaRC UPWT and BSWT was correct. The second objective, once the first objective was met, was to assess the performance increment of NCV over TCA accounting for the associated laminar run and trip drag corrections in LaRC UPWT. We know that the configurations tested have laminar flow on portions of the wing and have trip drag due to the mechanisms used to force the flow to go from laminar to turbulent aft of the transition location.
    Keywords: Aerodynamics
    Type: 1999 NASA High-Speed Research Performance Workshop; Volume 1; Part 2; 1197-1288; NASA/CP-1999-209704/VOL1/PT2
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  • 88
    Publication Date: 2004-12-03
    Description: An improved laminar run and trip drag correction methodology for supersonic cruise performance testing was derived. This method required more careful analysis of the flow visualization images which revealed delayed transition particularly on the inboard upper surface, even for the largest trip disks. In addition, a new code was developed to estimate the laminar run correction. Once the data were corrected for laminar run, the correct approach to the analysis of the trip drag became evident. Although the data originally appeared confusing, the corrected data are consistent with previous results. Furthermore, the modified approach, which was described in this presentation, extends prior historical work by taking into account the delayed transition caused by the blunt leading edges.
    Keywords: Aerodynamics
    Type: 1999 NASA High-Speed Research Performance Workshop; Volume 1; Part 2; 1163-1196; NASA/CP-1999-209704/VOL1/PT2
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  • 89
    Publication Date: 2004-12-03
    Description: In calculating the position vector of the Moon in on-board flight software, one often begins by using a series expansion to calculate the ecliptic latitude and longitude of the Moon, referred to the mean ecliptic and equinox of date. One then performs a reduction for precession, followed by a rotation of the position vector from the ecliptic plane to the equator, and a transformation from spherical to Cartesian coordinates before finally arriving at the desired result: equatorial J2000 Cartesian components of the lunar position vector. An alternative method is developed here in which the equatorial J2000 Cartesian components of the lunar position vector are calculated directly by a series expansion, saving valuable onboard computer resources.
    Keywords: Astronomy
    Type: 1999 Flight Mechanics Symposium; 175-184; NASA/CP-1999-209235
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  • 90
    Publication Date: 2004-12-03
    Description: The primary constituents of the Earth's atmosphere are molecular nitrogen and molecular oxygen. Ozone is created when ultraviolet light from the sun photodissociates molecular oxygen into two oxygen atoms. The oxygen atoms undergo many collisions but eventually combine with a molecular oxygen to form ozone (O3). The ozone molecules absorb ultraviolet solar radiation, primarily in the wavelength region between 200 and 300 nanometers, resulting in the dissociation of ozone back into atomic oxygen and molecular oxygen. The oxygen atom reattaches to an O2 molecule, reforming ozone which can then absorb another ultraviolet photon. This sequence goes back and forth between atomic oxygen and ozone, each time absorbing a uv photon, until the oxygen atom collides with and ozone molecule to reform two oxygen molecules.
    Keywords: Meteorology and Climatology
    Type: NASA Scientific Forum on Climate Variability and Global Change: UNISPACE 3; 1-14; NASA/CP-1999-209240
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  • 91
    Publication Date: 2004-12-03
    Description: Gradient-based optimization requires accurate derivatives of the objective function and constraints. These gradients may have previously been obtained by manual differentiation of analysis codes, symbolic manipulators, finite-difference approximations, or existing automatic differentiation (AD) tools such as ADIFOR (Automatic Differentiation in FORTRAN). Each of these methods has certain deficiencies, particularly when applied to complex, coupled analyses with many design variables. Recently, a new AD tool called ADJIFOR (Automatic Adjoint Generation in FORTRAN), based upon ADIFOR, was developed and demonstrated. Whereas ADIFOR implements forward-mode (direct) differentiation throughout an analysis program to obtain exact derivatives via the chain rule of calculus, ADJIFOR implements the reverse-mode counterpart of the chain rule to obtain exact adjoint form derivatives from FORTRAN code. Automatically-generated adjoint versions of the widely-used CFL3D computational fluid dynamics (CFD) code and an algebraic wing grid generation code were obtained with just a few hours processing time using the ADJIFOR tool. The codes were verified for accuracy and were shown to compute the exact gradient of the wing lift-to-drag ratio, with respect to any number of shape parameters, in about the time required for 7 to 20 function evaluations. The codes have now been executed on various computers with typical memory and disk space for problems with up to 129 x 65 x 33 grid points, and for hundreds to thousands of independent variables. These adjoint codes are now used in a gradient-based aerodynamic shape optimization problem for a swept, tapered wing. For each design iteration, the optimization package constructs an approximate, linear optimization problem, based upon the current objective function, constraints, and gradient values. The optimizer subroutines are called within a design loop employing the approximate linear problem until an optimum shape is found, the design loop limit is reached, or no further design improvement is possible due to active design variable bounds and/or constraints. The resulting shape parameters are then used by the grid generation code to define a new wing surface and computational grid. The lift-to-drag ratio and its gradient are computed for the new design by the automatically-generated adjoint codes. Several optimization iterations may be required to find an optimum wing shape. Results from two sample cases will be discussed. The reader should note that this work primarily represents a demonstration of use of automatically- generated adjoint code within an aerodynamic shape optimization. As such, little significance is placed upon the actual optimization results, relative to the method for obtaining the results.
    Keywords: Aerodynamics
    Type: HPCCP/CAS Workshop Proceedings 1998; 225-229; NASA/CP-1999-208757
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  • 92
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2004-12-03
    Description: Computations have been performed on the baseline Reference H wing/body configuration, as well as the Wing 704 configuration, an optimized wing and fuselage combination derived from Ref. H through automated optimization. The parabolized Navier-Stokes solver UPS was employed with viscous terms in two directions in an effort to understand the source and level of potential viscous/inviscid interactions. The paper briefly describes the UPS code and the grids used to obtain the solutions before the discussion of results. Results of these computations indicate that viscous/inviscid interaction can contribute increments to both the pressure- and friction-related drag. Computations were performed for wind tunnel conditions-1.675% scale models at a Reynolds number of 4 million per foot. Turbulent flow results were obtained using the Baldwin-Lomax algebraic turbulence model and were compared with laminar flow results. The laminar flow fields were used to obtain upper bounds on potential interaction effects.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 335-353; NASA/CP-1999-209690/PT2
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  • 93
    Publication Date: 2004-12-03
    Description: The NASA-industry team has sponsored several studies in the last two years to address the installed nozzle boattail drag issues. Some early studies suggested that nozzle boattail drag could be as much as 25 to 40 percent of the subsonic cruise. As part of this study tests have been conducted at NASA-Langley to determine the uninstalled drag characteristics of a proposed nozzle. The overall objective was to determine the effects of nozzle external flap curvature and sidewall boattail variations. This test would also provide data for validating CFD predictions of nozzle boattail drag.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 669-706; NASA/CP-1999-209691/VOL1/PT1
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  • 94
    Publication Date: 2004-12-03
    Description: The objective of this milestone is to assess the propulsion/airframe integration characteristics of the Technology Concept Airplane and design variations through computational analysis and experimental subsonic through supersonic wind tunnel testing. The Milestone will generate a comprehensive CFD and wind tunnel data base of the baseline, and design variations. Emphasis will be placed on establishing the propulsion induced effects on the flight performance of the Technology Concept Airplane with all appropriate wind tunnel corrections.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance; Volume 1; Part 2; 1550-1604; NASA/CP-1999-209691/VOL1/PT2
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  • 95
    Publication Date: 2004-12-03
    Description: The computational fluid dynamics (CFD) comparisons being presented are compared to each other and to wind tunnel (WT) data on the baseline TCA. Some of the CFD computations were done prior to the tests and others later. Only force data (CL vs CD) from CFD will be presented as part of this report. The WT data presented comes from the testing of the baseline TCA in the Langley Unitary Plan Wind Tunnel (UPWT), Test Section #2. There are 2 sets of wind tunnel data being presented: one from test 1671 of model 2a (flapped wing) and the other from test 1679 of model 2b (solid wing). Most of the plots show only one run from each of the WT tests per configuration. But many repeat runs were taken during the tests. The WT repeat runs showed an uncertainty in the drag of +/- 0.5 count. There were times when the uncertainty in drag was better, +/- 0.25 count. Test 1671 data was of forces and pressures measured from model 2a. The wing had cutouts for installing various leading and trailing edge flaps at lower Mach numbers. The internal duct of the nacelles are not designed and fabricated as defined in the outer mold lines (OML) iges file. The internal duct was fabricated such that a linear transition occurs from the inlet to exhaust. Whereas, the iges definition has a constant area internal duct that quickly transitions from the inlet to exhaust cross sectional shape. The nacelle internal duct was fabricated, the way described, to save time and money. The variation in the cross sectional area is less than 1% from the iges definition. The nacelles were also installed with and without fairings. Fairings are defined as the build up of the nacelles on the upper wing surface so that the nacelles poke through the upper surface as defined in the OML iges file. Test 1679 data was of forces measured from model 2a and 2b. The wing for model 2b was a solid wing. The nacelles were built the same way as for model 2a, except for the nacelle base pressure installation. The nacelles were only tested with the fairings for model 2a and 2b during test 1679.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance; Volume 1; Part 2; 1500-1549; NASA/CP-1999-209691/VOL1/PT2
    Format: text
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  • 96
    Publication Date: 2004-12-03
    Description: Configuration design at Ames was carried out with the SYN87-SB (single block) Euler code using a 193 x 49 x 65 C-H grid. The Euler solver is coupled to the constrained (NPSOL) and the unconstrained (QNMDIF) optimization packages. Since the single block grid is able to model only wing-body configurations, the nacelle/diverter effects were included in the optimization process by SYN87's option to superimpose the nacelle/diverter interference pressures on the wing. These interference pressures were calculated using the AIRPLANE code. AIRPLANE is an Euler solver that uses a unstructured tetrahedral mesh and is capable of computations about arbitrary complete configurations. In addition, the buoyancy effects of the nacelle/diverters were also included in the design process by imposing the pressure field obtained during the design process onto the triangulated surfaces of the nacelle/diverter mesh generated by AIRPLANE. The interference pressures and nacelle buoyancy effects are added to the final forces after each flow field calculation. Full details of the (recently enhanced) ghost nacelle capability are given in a related talk. The pseudo nacelle corrections were greatly improved during this design cycle. During the Ref H and Cycle 1 design activities, the nacelles were only translated and pitched. In the cycle 2 design effort the nacelles can translate vertically, and pitch to accommodate the changes in the lower surface geometry. The diverter heights (between their leading and trailing edges) were modified during design as the shape of the lower wing changed, with the drag of the diverter changing accordingly. Both adjoint and finite difference gradients were used during optimization. The adjoint-based gradients were found to give good direction in the design space for configurations near the starting point, but as the design approached a minimum, the finite difference gradients were found to be more accurate. Use of finite difference gradients was limited by the CPU time limit available on the Cray machines. A typical optimization run using finite difference gradients can use only 30 to 40 design variables and one optimization iteration within the 8 hour queue limit for the chosen grid size and convergence level. The efficiency afforded by the adjoint method allowed for 50-120 design variables and 5-10 optimization iterations in the 8 hour queue. Geometric perturbations to the wing and fuselage were made using the Hicks/Henne (HH) shape functions. The HH functions were distributed uniformly along the chords of the wing defining sections and lofted linearly. During single-surface design, constraints on thickness and volume at selected wing stations were imposed. Both fuselage camber and cross-sectional area distributions were permitted to change during design. The major disadvantage to the use of these functions is the inherent surface waviness produced by repeated use of such functions. Many smoothing operations were required following optimization runs to produce a configuration with reasonable smoothness. Wagner functions were also used on the wing sections but were never used on the fuselage. The Wagner functions are a family of increasingly oscillatory functions that have also been used extensively in airfoil design. The leading and trailing edge regions of the wing were designed by use of polynomial and monomial functions respectively. Twist was attempted but was abandoned because of little performance improvement available from changing the baseline twist.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 2; 1257-1347; NASA/CP-1999-209691/VOL1/PT2
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  • 97
    Publication Date: 2004-12-03
    Description: The TetrUSS (Tetrahedral Unstructured Software System), developed at NASA LaRC, enables one to take a vehicle from its surface definition to its analyzed solution. The important parts are the shape definition, accomplished in GRIDTOOL; the initial front and volume grid generation in VGRID; the flow solver USM3D, and the various ways used to post-process the computational results.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aeodynamic Performance Workshop; Volume 2; 2471-2507; NASA/CP-1999-209692/VOL2
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  • 98
    Publication Date: 2004-12-03
    Description: The objective of this study is to calibrate a Navier-Stokes code for the TCA (30/10) baseline configuration (partial span leading edge flaps were deflected at 30 degs. and all the trailing edge flaps were deflected at 10 degs). The computational results for several angles of attack are compared with experimental force, moments, and surface pressures. The code used in this study is CFL3D; mesh sequencing and multi-grid were used to full advantage to accelerate convergence. A multi-grid approach was used similar to that used for the Reference H configuration allowing point-to-point matching across all the trailingedge block interfaces. From past experiences with the Reference H (ie, good force, moment, and pressure comparisons were obtained), it was assumed that the mounting system would produce small effects; hence, it was not initially modeled. However, comparisons of lower surface pressures indicated the post mount significantly influenced the lower surface pressures, so the post geometry was inserted into the existing grid using Chimera (overset grids).
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aeodynamic Performance Workshop; Volume 2; 2691-2733; NASA/CP-1999-209692/VOL2
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  • 99
    Publication Date: 2004-12-03
    Description: The objective of the present study was to address the questions of: 1) how reliably or consistently the Navier-Stokes methods and processes used by the various organizations can predict integrated skin friction drag, and 2) how well the methods can predict trends within a family of optimized configurations. As a first step, all available skin friction drag predictions were accumulated to obtain a mean and standard deviation for the TCA (Technology Concept Airplane) baseline and each of the optimized configurations. It is observed that the optimization process has had little effect on the predicted skin friction drags. The variation in the mean that is observed is dwarfed by the standard deviations. In order to understand the reasons for the relatively large spreads in the computed results, a number of auxiliary computations have been performed using the UPS and OVERFLOW codes in an effort to identify and quantity potential sources of the variations.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 333-353; NASA/CP-1999-209692/VOL1/PT1
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  • 100
    Publication Date: 2004-12-03
    Description: The paper presents the recent progress made towards developing an efficient and user-friendly parallel environment for routine analysis of large CFD problems. The coarse-grain parallel version of the CFL3D Euler/Navier-Stokes analysis code, CFL3Dhp, has been ported onto most available parallel platforms. The CFL3Dhp solution accuracy on these parallel platforms has been verified with the CFL3D sequential analyses. User-friendly pre- and post-processing tools that enable a seamless transfer from sequential to parallel processing have been written. Static load balancing tool for CFL3Dhp analysis has also been implemented for achieving good parallel efficiency. For large problems, load balancing efficiency as high as 95% can be achieved even when large number of processors are used. Linear scalability of the CFL3Dhp code with increasing number of processors has also been shown using a large installed transonic nozzle boattail analysis. To highlight the fast turn-around time of parallel processing, the TCA full configuration in sideslip Navier-Stokes drag polar at supersonic cruise has been obtained in a day. CFL3Dhp is currently being used as a production analysis tool.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 171-203; NASA/CP-1999-209692/VOL1/PT1
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