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  • Biology
  • Fluid Mechanics and Thermodynamics
  • 2010-2014  (627)
  • 1950-1954  (30)
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  • 1
    Publication Date: 2021-05-19
    Description: Se incluyen en el análisis 271 trabajos publicados en diversas revistas científicas y cuyo material básico de estudio fue observado, colectado y analizado en el Caribe colombiano, pero fundamentalmente en el área de influencia directa del INVEMAR. Las contribuciones han sido publicadas en alemán (111), español (109) e inglés (51). Dichos trabajos incluyen investigaciones de carácter descriptivo (175) y analítico (96) e involucran el ambiente terrestre (91) y el acuático (180). Las regiones incluidas en loa estudios son: Parque Tayrona (84), Santa Marta (59), Ciénaga Grande (51) y otras áreas (77); y en cuanto a las ramas de la ciencias: la Biología (212), la Geología (9) y otras áreas (50).
    Description: Two hundred and seventy one works published in different scientific journals are included and whose basic study material was observed, collected and analized in the Colombian Caribbean, but basically in INVEMAR direct influence área. The contributions have been published in Germán (111), Spanish (109)and English (51). These works include research of descriptive character (175) and analitic (96), and involve land (91) and aquatic (180) environments. The regions included in the studies are the following: Tayrona Park (84), Santa Marta (59), Ciénaga Grande (51), and other arcas (77); and concerning the scientific branches: Biology (212), Geology (9) and other arcas (50).
    Description: Published
    Description: Bibliography,
    Keywords: Estuaries ; Geology ; Coastal lagoons ; Biology ; Coastal lagoons ; Estuaries ; Biology ; Geology
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 2
    Publication Date: 2021-05-19
    Description: During a 3 week study, a total of 55 individuals of the redlip blenny (Ophioblennius atlanticus) were observed for at least two 15-minute periods, and several for ten of such periods. The sizes of their territories were estimated, the color pattern of each specimen an intra and interspecific interactions were recorded. The mean territory size of the redlip blenny in the study area appeared to be greater than that of these blennies studied in Curacao and Barbados by NURSALL (1977), the difference reflecting perhaps different methods of identifying the territories or a lower density of O. atlanticus in the Santa Marta área. Territories did not appear to be as consistently defended at the study area as at Barbados/Curacao and our impression ¡s that individuals holding large territories are less likely to defend their borders. It seems possible that light colored individuals are protected by their coloration from attack by dark colored territory owners. In territorial defense the redlip blennies grabbed each other tighthy by the mouth and struggled in this position repeatedly for about 15 seconds. Interspecific antagonism was common in the present study, the redlip blennics defended their territory frequently against Eupomacentrus dorsopunicans or E. partitus.
    Description: Durante un estudio de tres semanas, un total de 5 i individuos del bií'nido Ojih'toblcnnius atlnniicur. fueron observados por lo menos durante dos períodos de 1 í minutos para cada individuo y en algunos casos hasta por 10 de estos periodos. Se estimó el área de sus respectivos territorios y se tomó notí de los patrones de coloración de cada espécimen y de las relaciones intra e interespecificas de ellos. El tamaño promedio del territorio de estos blénidos resultó ser mayor que el de los respectivos territorios estudiados por NURSALL (1977) en Curacao y Barbados. Esta diferencia posiblemente se debe a un método diferente de definir los territorios o refleja una densidad menor de la población de O. aílanticus en Santa Marta, Los territorios del área fueron defendidos con menor intensidad a como lo fueron los de Barbados/ Curacao y es nuestra impresión que individuos ocupando un territorio extenso tienden a defender sus límites en menor grado. El color claro de algunos individuos probablemente los protege de agresiones por parte de individuos de color oscuro. En el acto de defensa territorial intraespecífica, los blénidos se agarran por sus bocas y se sacuden mutuamente durante aproximadamente 15 segundos , pudiéndose repetir esti varias veces. Con frecuencia se observarondefensas de los territorios dirigidas hacia los peces doncella Eupomacentrus dorsopunicnas y E. partitus.
    Description: Published
    Keywords: Fisheries ; Biology ; Fisheries ; Biology
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 3
    Publication Date: 2021-05-19
    Description: Sícydium antillarum Grant es un gobiido abundante en las corrientes que bajan de la SierraNevada de Santa Marta (Colombia) al mar. Se estudió la población de la Quebrada Valencia y las postlarvas en las bocas de los ríos Manzanares y Gaira, entre febrero de 1987 y enero de 1988. Se presentan datos morfológicos, merísticos y morfométricos de la especie; la población desovó de mayo a diciembre, con picos máximos en junio y octubre. La proporción hembras: machos fue casi 1:1 de enero a marzo; de abril a diciembre los machos se apoderan de un territorio y se dificulta su captura, principalmente en septiembre y octubre (proporción 9:1). La fecundidad máxima fue de 91067 huevos en una hembra de 109 mm; el 25% de los ejemplares alcanzó la madurez entre 60.0 y 64.9 mm. La relación talla (mm) - peso (gr) fue: Peso = 1.039x10'6 xlongitud total 35232 . El factor de condición sufre un descenso en noviembre, después del mayor pico de desove de la estación lluviosa. Los contenidos estomacales estaban integrados por algas y bacterias; la especie es diurna, encontrándose el 100% de individuos con el estómago lleno a las 15:00 horas. Las postlarvas fueron detectadas cada mes entre agosto y diciembre, al fin del cuarto menguante; adultos y postlarvas son resistentes a condiciones de laboratorio.
    Description: Sicydium antillarum Grant is an abundant gobiidfish ¡n the streams which runfrom the Sierra Nevada de Santa Marta (Colombia) tothe sea. The population living in the Quebrada Valencia was studiedfrom February 1987 to January 1988; postlarvae were observed and collected at the mouths of the Manzanares and Gaira rivers. Morphological, meristic and morphometric data of the species are presented; the population spawned between May and December, with peaks in June and October. Sex ratios between January and March were around 1:1; males defend a territory from April to December and are more difficult to capture (mainly in September and October, when the ratios are about ninefemales per male). The highest numberof eggs (91,067) was found in a female 109 mm in íength. Twenty-five per cent of the specimens reached maturity between 60.0 and 64.9 mm. The equation relating íength (mm) and weigth (gr) is: Weígth = 1.0309xtO*6 xtotal íength 35232 . Condition factor reached a low valué in November.that is after the highest spawning peak of the rainy season. The stomach contents studied were composed of algae and bacteria; all the specimens collected at 15:00 had a full stomach, which indicates that the species is diurnal. Postlarvae were detected monthly from August top December, always related to the waning moon. Adults and postlarvae are very hardy and live well in laboratory conditions.
    Description: Published
    Keywords: Ecology ; Geographical distribution ; Reproductive behaviour ; Feeding behaviour ; Ichthyology ; Biology ; Ecology ; Ichthyology ; Geographical distribution ; Reproductive behaviour ; Feeding behaviour ; Biology ; Morphometry ; Stomach content
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 4
    Publication Date: 2021-05-19
    Description: Se describen 19 especies de peces colectadas en los archipiélagos coralinos de las islas del Rosario y de San Bernardo, las cuales son nuevos registros para el Caribe continental colombiano. Tres de esas especies (Ichthyapus ophioneus, Calamopteryx goslinei y Apogon leptocaulus) no habían sido colectadas antes en el Caribe sur, por lo que estos récords son nuevos para este sector del Mar de las Antillas. Se incluye información sobre aspectos biológicos y ecológicos de las especies.
    Description: 19 species of fishes coliected in the coralline archipelagos of Islas de) Rosario and San Bernardo, which are reponed for the first time for the Colombian continental Car¡bbean, are described. Three of those species (Ichtyapus ophioncus, Calamopteryx goslmei and Apogon leptocaulus) had not been collected before in the southern Caribbean, being therefore new records for this section of the Sea. Biological and ecological information about the 19 species is given as well.
    Description: Published
    Keywords: Fish ; Ecology ; Biology ; Fish ; New records ; Biology ; Ecology
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 5
    Publication Date: 2021-05-19
    Description: El objetivo de esta tesis es caracterizar las poblaciones naturales de Ulva fasciata en el sector comprendido entre los ríos Quibú y Jaimanitas al oeste de La Habana, típico de costas de emersión del Caribe Occidental, con vistas a su posible explotación. El estudio se realizó entre marzo de 1996 y enero del 2001. Los resultados más importantes permitieron comprobar que la especie U. fasciata no se distribuye de forma similar en todo este sector, en la cobertura algal intervienen de manera decisiva, el tipo de sustrato y la disponibilidad de nutrientes en el medio. Los compuestos del nitrógeno y el fósforo en el agua de mar y las diferencias en la amplitud de variación de los mismos, justifican las diferencias en la morfometría, la biomasa en pie y el estado nutricional (C, N, P) de U. fasciata y evidencia el carácter oportunista de la especie. Estas condiciones ambientales son poco variables en el tiempo, este hecho garantiza la presencia de su población, cada año, en este sector. El desarrollo de la población de U. fasciata, se favorece cuando la temperatura superficial del mar oscila entre 24ºC y 26,5ºC, los niveles de radiación global fluctúan entre 13,4 mj.m-2 y 24 mj.m-2 y acontecen precipitaciones moderadas que no exceden los 190 mm de acumulado mensual. La biomasa en pie decrece considerablemente en el verano, coincidiendo con las altas temperaturas superficiales del mar (29ºC-30ºC) y las precipitaciones intensas (〉190 mm acumulado mensual). Aunque la biomasa por unidad de área fluctúa en el tiempo, su ciclo anual tiene un patrón muy similar en todo el sector. U. fasciata tiene un contenido alto de clorofila a y b, carotenoides, proteína, carbohidratos, fibra y cenizas, así como de otros macronutrientes (Ca, Mg y K) y micronutrientes (Fe, Zn, Cr y Mn). La concentración de estos componentes manifiesta variaciones espaciales y temporales de acuerdo a los diferentes niveles de nutrifización del medio. Las concentraciones máximas de componentes en los talos coinciden con las mayores acumulaciones de biomasa en pie y acontecen en las zonas cercanas a los ríos. Esta especie posee bajo contenido de lípidos. Existen niveles altos de bacterias coliformes totales y fecales en U. fasciata, por lo que su calidad higiénico-sanitaria no siempre es buena y debe ser tratada si se desea explotar este recurso para diferentes fines.
    Description: Ulva fasciata, explotación
    Keywords: Algae ; Biology ; Algae ; Biology
    Repository Name: AquaDocs
    Type: Theses and Dissertations
    Format: 150pp.
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  • 6
    Publication Date: 2021-05-19
    Description: The pearl oyster Pinctada radiata and the cockle Cerastoderma glaucum are among the most abundant bivalve molluscs in southern Tunisian waters. These species are not currently subject to any investigation despite their important economic value in the world. For this reason, their biological parameters, their spatial distribution and their stock assessment were undertaken in the Gulf of Gabes. The reproductive cycle was studied in relation to variations of the environment parameters. The specimens were collected monthly during one year (2007) in sites of El Kraten and El Jorf (Kerkennah Islands) for the first species and sites of Sidi Mansour and El Hicha (North of Sfax and Gabes) for the second. An intraspecific polymorphism biometric trait for P. radiata and C. glaucum was performed using statistical comparison methods and multivariate analysis methods. Results of analyzes showed heterogeneity between populations. For Pinctada radiata, the sex ratio unbalanced, although males dominated among smaller individuals and females were predominant in larger size-classes. Evidence of protrandric hermaphroditism was observed with males maturing earlier than females. Seasonal changes in macroand microscopic properties of the gonads of both sexes showed that this species displayed a clearly defined annual reproductive cycle with a major peak in summer and a minor peak in autumn. The onset of reproduction appears to be triggered by the rising seawater temperature during spring and summer. P. radiata exhibited a short resting phase that occurred simultaneously in both sexes from the end of December until early February. For Cerastoderma glaucum, the overall samples presented a balanced sex ratio, with males dominating among smaller individuals and females predominating in larger size classes. The seasonal changes assessed through macro- and microscopic properties in the gonads of both sexes indicated a clearly defined annual reproductive cycle. Reproductive activity of C. glaucum was greatest from spring to late autumn, with two reproductive peaks (May and November). Gametogenic activity in both sexes was apparently triggered by the rising seawater temperature during spring and summer. These results support previous findings of latitudinal changes in the reproductive behaviour of C. glaucum. Due to the extensive period of gonadal activity, C. glaucum exhibited a short resting phase that occurred simultaneously in both sexes throughout January and February. In terms of stock assessment and spatial distribution of P. radiata, results showed a scattered distribution pattern of the species according to location and depth ranging between 0 and 145 ind.m-². P. radiata was encountered from the intertidal zone to 40 m depth, with a highest population densities recorded at depth range of 2-20 m. The total stock was estimated to be 27584.9 ± 11504.5 million individuals. Oyster distribution seems influenced by the substrate type. This high population of pearl oysters was associated with large cover of seagrass Posidonia oceanica which provides an excellent substratum for attachment. The littoral zone seems not to be the preferred habitat for the proliferation of this immigrant species. Oysters’ size increased steadily with depth, ranging from a mean of 37.98 ± 0.40 mm SH at 0-1 m to 60.98 ± 0.68 mm SH at 20-100 m depth range. Size structure analysis showed that deep water population was dominated by large individuals reaching 96 mm SH. In terms of geographical occupation and stock assessment of C. glaucum, results showed a scattered distribution pattern of the species according to location. The consequence was a remarkable biomass which represented 4736 tons of total fresh weight and high abundance levels reaching over 1982 million individuals estimated in the area of 20122 hectares. In conclusion, this study is the first report of an extraordinary abundance of Pinctada radiata and Cerastoderma glaucum in southern Tunisian waters. It gives more information about their stocks in the colonization area. The data may help to determine future quantitative changes indicating trends in the study area that are exposed to various factors of environmental conditions and human activities.
    Description: Submitted
    Description: ABONDANCE
    Description: BILOGIE
    Description: Pinctada radiata
    Description: Cerastoderma glaucum
    Description: Huitre perlière
    Keywords: Abundance ; Biology ; Shellfish
    Repository Name: AquaDocs
    Type: Theses and Dissertations , Phd thesis
    Format: 170
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  • 7
    Publication Date: 2021-05-19
    Description: A yield per recruit model has been used to compare the effects of mesh size increment on the yields and revenues of the fisheries of Cameroon under two different cases. Case 1 assumes the commercial fishery to move from the exploitation of three age-groups to two age-groups with no interactions with the artisanal fishery, whereas Case 2 takes into account these interactions. The difference in the percentage increase of yield per recruit between case 1 and case 2 is 61% at current fishing (46% and 18% yield per recruit increment in cases 1 and 2 respectively). The usually accepted long-term yield per recruit increment with increase of age at first capture (with a single non-interacting fisheries) is, in this case, cancelled out. However, the revenues increase by 72% and 63% in cases 1 and 2 respectively. Therefore the economic approach, compared with purely biological analyses, is more convincing. In general, as fisheries always interact, a single-fishery management approach should not be the rule as it is at present; management strategies should consider interactions between different fisheries and be based on their economic performances and not, as said earlier, on purely biological considerations. This is because a biological approach to fisheries management will, at best, be modified by economic factors, or, at worst, be ignored totally in favour of economic policies.
    Description: Published
    Keywords: Biology ; Fisheries ; Biological interaction ; Sciaenidae ; Fisheries development ; Fishery management ; Yield/recruit ; Commercial fisheries ; Artisanal fishing
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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  • 8
    Publication Date: 2021-05-19
    Description: Published
    Description: Chinchard (Trachuurus trecae)
    Description: Biologie
    Keywords: Biology ; Exploitation
    Repository Name: AquaDocs
    Type: Journal Contribution , Non-Refereed , Article
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  • 9
    Publication Date: 2021-05-19
    Description: Instittuto Nacional de Investigaçao Pesqueira, INIP, luanda , Angola
    Description: Bachelors
    Description: Trabaho de fin cdoursado para obtençâo do grau de licenciatura em Biologica
    Description: Published
    Description: biologia marinha, fitoplâncton, limnologia, algas
    Description: marine biology, phytoplankton, algae,
    Keywords: Phytoplankton ; Nannoplankton ; Biology ; Limnology ; Algae
    Repository Name: AquaDocs
    Type: Theses and Dissertations , Bachelor thesis
    Format: 56
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  • 10
    Publication Date: 2021-05-19
    Description: Published
    Description: langoustes
    Description: marquage
    Description: poisson
    Keywords: Lobsters ; Biology ; Ecology ; Aquatic biology
    Repository Name: AquaDocs
    Type: Journal Contribution , Non-Refereed , Article
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  • 11
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1895
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
    Type: Text
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  • 12
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1893
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
    Type: Text
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  • 13
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1890
    Description: Preface -- Specialization and organization, companion principles of all progress. The most important need of american biology, by C.O. Whitman -- Naturalist's occupation: 1. general survey. 2. a special problem, by C.O. Whitman -- Some problems of Annelid morphology, by E.B. Wilson -- Gastraea theory and its successors, by J.P. McMurrich -- Weismann and Maupas on the origin of death, by Edward G. Gardiner -- Evolution and heredity, by Henry Fairfield Osborn -- Relationships of the sea-spiders, by T.H. Morgon -- On caryokinesis, by S. Watase -- Ear of man: its past, present and future, by Howard Ayers -- Study of Ocean temperatures and currents, by William Libbey, Jr.
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
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  • 14
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1894
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
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  • 15
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    Marine Biological Laboratory (Woods Hole, Mass.) | Biodiversity Heritage Library
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1899
    Description: Evolution of the sporophyte in the higher plants, by Douglas Houghton Campbell -- Nature of the evidence exhibited by fossil plants, and its bearing upon our knowledge of the history of plant life, by D.P. Penhallow -- Influence of inversions of temperature, ascending and descending currents of air, upon distribution, by D.T. MacDougal -- Significance of mycorrhizas, by D.T. MacDougal -- Instinct, by Edward Thorndike -- Associative processes in animals, by Edward Thorndike -- Behavior of unicellular organisms, by Herbert S. Jennings -- Blind-fishes, by Carl H. Eigenmann -- Some governing factors usually neglected in biological investigations, by Alpheus Hyatt -- On the development of color in moths and butterflies, by Alfred Goldsborough Mayer -- Physiology of secretion, by A. Mathews -- Regeneration: old and new interpretations, by T.H. Morgan -- Nuclear division in protozoa, by Gary N. Calkins -- Significance of the spiral type of cleavage and its relation to the process of differentiation, by C.M. Child -- Aims of the quantitative study of variation, by C.B. Davenport -- On the nature of the process of fertilization, by Jacques Loeb
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
    Type: Text
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  • 16
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1896-1897
    Description: Variations and mutations of the introduced sparrow. Passer domesticus, by Hermon C. Bumpus -- Cleavage and differentiation, by E.G. Conklin -- Centrosomes of the fertilized egg of Allolobophora foetida, by Katharine Foot -- Methods of palacontological inquiry, by W.B. Scott -- Physiology of excretion, by Arnold Graf -- Some neural terms, by Burt G. Wilder -- Classification of the North American Taxaccae and Coniferae on the basis of the stem structre, by D.P. Penhallow -- Selection of plant types for the general biology ccourse, by James Ellis Humphrey -- Rate of Cell-division and the function of the centrosome, by A.D. Mead -- Coalescence experiments upon the Lepidoptera, by Henry E. Crampton, Jr. -- Some of the functions and features of a biological station, by C.O. Whitman
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
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  • 17
    Publication Date: 2023-01-12
    Description: Biological lectures given at the Marine Biological Laboratory in Woods Hole in the summer of 1898
    Description: Publications
    Keywords: Biology ; Publications
    Repository Name: Woods Hole Open Access Server
    Language: English
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  • 18
    Publication Date: 2010-02-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilson, Edward O -- New York, N.Y. -- Science. 2010 Feb 12;327(5967):775. doi: 10.1126/science.327.5967.775.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20150461" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ants ; Biology ; *Ecosystem ; *Literature, Modern
    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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  • 19
    Publication Date: 2013-04-05
    Description: The technological demand to push the gigahertz (10(9) hertz) switching speed limit of today's magnetic memory and logic devices into the terahertz (10(12) hertz) regime underlies the entire field of spin-electronics and integrated multi-functional devices. This challenge is met by all-optical magnetic switching based on coherent spin manipulation. By analogy to femtosecond chemistry and photosynthetic dynamics--in which photoproducts of chemical and biochemical reactions can be influenced by creating suitable superpositions of molecular states--femtosecond-laser-excited coherence between electronic states can switch magnetic order by 'suddenly' breaking the delicate balance between competing phases of correlated materials: for example, manganites exhibiting colossal magneto-resistance suitable for applications. Here we show femtosecond (10(-15) seconds) photo-induced switching from antiferromagnetic to ferromagnetic ordering in Pr0.7Ca0.3MnO3, by observing the establishment (within about 120 femtoseconds) of a huge temperature-dependent magnetization with photo-excitation threshold behaviour absent in the optical reflectivity. The development of ferromagnetic correlations during the femtosecond laser pulse reveals an initial quantum coherent regime of magnetism, distinguished from the picosecond (10(-12) seconds) lattice-heating regime characterized by phase separation without threshold behaviour. Our simulations reproduce the nonlinear femtosecond spin generation and underpin fast quantum spin-flip fluctuations correlated with coherent superpositions of electronic states to initiate local ferromagnetic correlations. These results merge two fields, femtosecond magnetism in metals and band insulators, and non-equilibrium phase transitions of strongly correlated electrons, in which local interactions exceeding the kinetic energy produce a complex balance of competing orders.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Li, Tianqi -- Patz, Aaron -- Mouchliadis, Leonidas -- Yan, Jiaqiang -- Lograsso, Thomas A -- Perakis, Ilias E -- Wang, Jigang -- England -- Nature. 2013 Apr 4;496(7443):69-73. doi: 10.1038/nature11934.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23552945" target="_blank"〉PubMed〈/a〉
    Keywords: Biology ; Chemistry ; Circular Dichroism ; Electronics ; Iron/chemistry ; *Magnetic Phenomena ; Magnetics ; Optics and Photonics ; Photosynthesis ; *Quantum Theory ; Temperature ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 20
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    Nature Publishing Group (NPG)
    Publication Date: 2013-09-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉England -- Nature. 2013 Sep 12;501(7466):136.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24032131" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Autobiography as Topic ; Biology ; *Literature, Modern ; Physics ; *Research Personnel ; Self Concept
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 21
    Publication Date: 2010-03-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, Jocelyn -- Regalado, Antonio -- New York, N.Y. -- Science. 2010 Mar 12;327(5971):1308-9. doi: 10.1126/science.327.5971.1308.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20223953" target="_blank"〉PubMed〈/a〉
    Keywords: Biology ; Biotechnology ; Chile ; *Disasters ; *Earthquakes ; Laboratories ; *Research ; Universities
    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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  • 22
    Publication Date: 2018-06-11
    Description: The National Aeronautics and Space Administration (NASA) is sending a large (〉850 kg) rover as part of the Mars Science Laboratory (MSL) mission to Mars in 2011. The rover's primary power source is a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) that generates roughly 2000 W of heat, which is converted to approximately 110 W of electrical power for use by the rover electronics, science instruments, and mechanism-actuators. The large rover size and extreme thermal environments (cold and hot) for which the rover is designed for led to a sophisticated thermal control system to keep it within allowable temperature limits. The pre-existing Martian atmosphere of low thermal conductivity CO2 gas (8 Torr) is used to thermally protect the rover and its components from the extremely cold Martian environment (temperatures as low as -130 deg C). Conventional vacuum based insulation like Multi Layer Insulation (MLI) is not effective in a gaseous atmosphere, so engineered gaps between the warm rover internal components and the cold rover external structure were employed to implement this thermal isolation. Large gaps would lead to more thermal isolation, but would also require more of the precious volume available within the rover. Therefore, a balance of the degree of thermal isolation achieved vs. the volume of rover utilized is required to reach an acceptable design. The temperature differences between the controlled components and the rover structure vary from location to location so each gap has to be evaluated on a case-by-case basis to arrive at an optimal thickness. For every configuration and temperature difference, there is a critical thickness below which the heat transfer mechanism is dominated by simple gaseous thermal conduction. For larger gaps, the mechanism is dominated by natural convection. In general, convection leads to a poorer level of thermal isolation as compared to conduction. All these considerations play important roles in the optimization process. A three-step process was utilized to design this insulation. The first step is to come up with a simple, textbook based, closed-form equation assessment of gap thickness vs. resultant thermal isolation achieved. The second step is a more sophisticated numerical assessment using Computational Fluid Dynamics (CFD) software to investigate the effect of complicated geometries and temperature contours along them to arrive at the effective thermal isolation in a CO2 atmosphere. The third step is to test samples of representative geometries in a CO2 filled chamber to measure the thermal isolation achieved. The results of these assessments along with the consistency checks across these methods leads to the formulation of design-guidelines for gap implementation within the rover geometry. Finally, based on the geometric and functional constraints within the real rover system, a detailed design that accommodates all these factors is arrived at. This paper will describe in detail this entire process, the results of these assessments and the final design that was implemented.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 23
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    Publication Date: 2018-06-11
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
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  • 24
    Publication Date: 2018-06-28
    Description: In recent years, both Europe and the US are developing hypersonic research and operational vehicles. These include (re)entry capsules (both ballistic and lifting) and lifting bodies such as ExoMars, EXPERT, ARV, CEV and IXV. The research programs are meant to enable technology and engineering capabilities to support during the next decade the development of affordable (possibly reusable) space transportation systems as well as hypersonic weapons systems for time critical targets. These programs have a broad range of goals, ranging from the qualification of thermal protection systems, the assessment of RCS performances, the development of GNC algorithms, to the full demonstration of the performance and operability of the integrated vehicles. Since the aerothermodynamic characteristics influence nearly all elements of the vehicle design, the accurate prediction of the aerothermal environment is a prerequisite for the design of efficient hypersonic systems. Significant uncertainties in the prediction of the hypersonic aerodynamic and the aerothermal loads can lead to conservative margins in the design of the vehicle including its Outer Mould Line (OML), thermal protection system, structure, and required control system robustness. The current level of aerothermal prediction uncertainties results therefore in reduced vehicle performances (e.g., sub-optimal payload to mass ratio, increased operational constraints). On the other hand, present computational capabilities enable the simulation of three dimensional flow fields with complex thermo-chemical models over complete trajectories and ease the validation of these tools by, e.g., reconstruction of detailed wind tunnel tests performed under identified and controlled conditions (flow properties and vehicle attitude in particular). These controlled conditions are typically difficult to achieve when performing in flight measurements which in turn results in large associated measurement uncertainties. Similar problems arise when attempting to rebuild measurements performed in "hot" ground facilities, where the difficulty level is increased by the addition of the free-flow characterization itself. The implementation of ever more sophisticated thermochemical models is no obvious cure to the aforementioned problems since their effect is often overwhelmed by the large measurement uncertainties incurred in both flight and ground high enthalpy facilities. Concurrent to the previous considerations, a major contributor to the overall vehicle mass of re-entry vehicles is the afterbody thermal protection system. This is due to the large acreage (equal or bigger than that of the forebody) to be protected. The present predictive capabilities for base flows are comparatively lower than those for windward flowfields and offer therefore a substantial potential for improving the design of future re-entry vehicles. To that end, it is essential to address the accuracy of high fidelity CFD tools exercised in the US and EU, which motivates a thorough investigation of the present status of hypersonic flight afterbody heating. This paper addresses the predictive capabilities of after body flow fields of re-entry vehicles investigated in the frame of the NATO/RTO - RTG-043 Task Group and is structured as follows: First, the verification of base flow topologies on the basis of available wind-tunnel results performed under controlled supersonic conditions (i.e., cold flows devoid of reactive effects) is performed. Such tests address the detailed characterization of the base flow with particular emphasis on separation/reattachment and their relation to Mach number effects. The tests have been performed on an Apollo-like re-entry capsule configuration. Second, the tools validated in the frame of the previous effort are exercised and appraised against flight-test data collected during the Apollo AS-202 re-entry.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Assessment of Aerothermodynamic Flight Prediction Tools Through Ground and Flight Experimentation; 6-1 - 6-32; AC/323(AVT-136)TP/388
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  • 25
    Publication Date: 2019-06-28
    Description: An approximate method for development of flow and thermal boundary layers in laminar regime on cylinders with arbitrary cross section and transpiration-cooled walls is obtained by use of Karman's integrated momentum equation and an analogous heat-flow equation. Incompressible flow with constant property values throughout boundary layer is assumed. Shape parameters for approximated velocity and temperature profiles and functions necessary for solution of boundary-layer equations are presented as charts, reducing calculations to a minimum. The method is applied to determine local heat-transfer coefficients and surface temperature-cooled turbine blades for a given flow rate. Coolant flow distributions necessary for maintaining uniform blade temperatures are also determined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E51F22
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  • 26
    Publication Date: 2019-06-28
    Description: The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 10 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, and (3) local rate of water impingement. These impingement characteristics are compared briefly with those previously reported for an ellipsoid of revolution with a fineness ratio of 5.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-3147
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  • 27
    Publication Date: 2019-06-28
    Description: An investigation at a free-stream Mach number of 2.02 was made to determine the effects of a propulsive jet on a wing surface located in the vicinity of a choked convergent nozzle. Static-pressure surveys were made on a flat surface that was located in the vicinity of the propulsive jet. The nozzle was operated over a range of exit pressure ratios at different fixed vertical distances from the flat surface. Within the scope of this investigation, it was found that shock waves, formed in the external flow because of the presence of the propulsive jet, impinged on the flat surface and greatly altered the pressure distribution. An integration of this pressure distribution, with the location of the propulsive jet exit varied from 1.450 propulsive-jet exit diameters to 3.392 propulsive-jet exit diameters below the wing, resulted in an incremental lift for all jet locations that was equal to the gross thrust at an exit pressure ratio of 2.86. This incremental lift increased with increase in exit pressure ratio, but not so rapidly as the thrust increased, and was approximately constant at any given exit pressure ratio.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-L54E05a
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  • 28
    Publication Date: 2019-06-28
    Description: Numerical solutions of the differential equation obtained from the momentum theorem for the development of a turbulent boundary layer along a thermally insulated surface in two-dimensional and in radial shock-free flow are presented in tabular form for a range of Mach numbers from 0.100 to 10. The solution can be used in a step-wise procedure with any given distribution of favorable pressure gradients and for zero pressure gradients. Solutions are also given for use with moderate adverse pressure gradients. The mean velocity in the boundary layer is approximated by a power-law profile. In view of the stepwise integration methods to be used, the exponent designated the profile shape can be varied along the surface between the integral fraction limits 1/5 and 1/11 through interpolation. Agreement obtained between theoretical and experimental boundary-layer development in a supersonic nozzle at a nominal Mach number of 2 indicates the general validity of the approximations used in the analysis - in particular, the method of extrapolating low-speed skin-friction relations to high Mach number flows. The extrapolation method used assumes that the skin-friction coefficient depend primarily on Reynolds number, provided that the density and the kinematic viscosity are evaluated at surface conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2045
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  • 29
    Publication Date: 2019-06-28
    Description: The condensation pressure of air was determined over the range of temperature from 60 to 85 K. The experimental results were slightly higher than the calculated values based on the ideal solution law. Heat of vaporization of oxygen was determined at four temperatures ranging from about 68 to 91 K and of nitrogen similarly at four temperatures ranging from 62 to 78 K.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2969
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  • 30
    Publication Date: 2019-06-28
    Description: The heat requirements for the icing protection of two radome configurations have been studied over a range of design icing conditions. Both the protection limits of a typical thermal protection system and the relative effects of the various icing variables have been determined. For full evaporation of all impinging water, an effective heat density of 14 watts per square inch was required. When a combination of the evaporation and running wet surface systems was employed, a heat requirement of 5 watts per square inch provided protection at severe icing and operating conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E53A22
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  • 31
    Publication Date: 2019-06-28
    Description: The Navier-Stokes equations of motion and the equation of continuity are transformed so as to apply to an orthogonal curvilinear coordinate system rotating with a uniform angular velocity about an arbitrary axis in space. A usual simplification of these equations as consistent with the accepted boundary-layer theory and an integration of these equations through the boundary layer result in boundary-layer momentum-integral equations for three-dimensional flows that are applicable to either rotating or nonrotating fluid boundaries. These equations are simplified and an approximate solution in closed integral form is obtained for a generalized boundary-layer momentum-loss thickness and flow deflection at the wall in the turbulent case. A numerical evaluation of this solution carried out for data obtained in a curving nonrotating duct shows a fair quantitative agreement with the measures values. The form in which the equations are presented is readily adaptable to cases of steady, three-dimensional, incompressible boundary-layer flow like that over curved ducts or yawed wings; and it also may be used to describe the boundary-layer flow over various rotating surfaces, thus applying to turbomachinery, propellers, and helicopter blades.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TR-1067
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  • 32
    Publication Date: 2018-06-06
    Description: The recent fusion of decades of advancements in mathematical models, numerical algorithms and curve fitting techniques marked the beginning of a new era in the science of simulation. It is becoming indispensable to the study of rockets and aerospace analysis. In pneumatic system, which is the main focus of this paper, particular emphasis will be placed on the efforts of compressible flow in Attitude Control System of sounding rocket.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 33
    Publication Date: 2019-07-27
    Description: An orifice element is commonly used in liquid rocket engine test facilities either as a flow metering device, a damper for acoustic resonance or to provide a large reduction in pressure over a very small distance in the piping system. While the orifice as a device is largely effective in stepping down pressure, it is also susceptible to a wake-vortex type instability that generates pressure fluctuations that propagate downstream and interact with other elements of the test facility resulting in structural vibrations. Furthermore in piping systems an unstable feedback loop can exist between the vortex shedding and acoustic perturbations from upstream components resulting in an amplification of the modes convecting downstream. Such was the case in several tests conducted at NASA as well as in the Ariane 5 strap-on P230 engine in a static firing test where pressure oscillations of 0.5% resulted in 5% thrust oscillations. Exacerbating the situation in cryogenic test facilities, is the possibility of the formation of vapor clouds when the pressure in the wake falls below the vapor pressure leading to a cavitation instability that has a lower frequency than the primary wake-vortex instability. The cavitation instability has the potential for high amplitude fluctuations that can cause catastrophic damage in the facility. In this paper high-fidelity multi-phase numerical simulations of an orifice element are used to characterize the different instabilities, understand the dominant instability mechanisms and identify the tonal content of the instabilities.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: SSTI-8080-0067
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  • 34
    Publication Date: 2019-07-27
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-18462 , Propulsion Control and Diagnostics (PCD) Workshop; 28 Fe. 1 Mar. 2012; Cleveland, OH; United States
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  • 35
    Publication Date: 2019-07-27
    Description: Marshall Space Flight Center (MSFC) is the National Aeronautics and Space Administration (NASA)-designated center for the development of space launch systems. MSFC is particularly known for propulsion system development. Many engineering skills and technical disciplines are needed to accomplish this mission. This presentation will focus on the work of the Fluid Dynamics Branch (ER42). ER42 resides in the Propulsion Systems Department at MSFC. The branch is responsible for all aspects of the discipline of fluid dynamics applied to propulsion or propulsion-induced loads and environments. This work begins with design trades and parametric studies, and continues through development, risk assessment, anomaly investigation and resolution, and failure investigations. Applications include the propellant delivery system including the main propulsion system (MPS) and turbomachinery; combustion devices for liquid engines and solid rocket motors; coupled systems; and launch environments. An advantage of the branch is that it is neither analysis nor test centric, but discipline centric. Fluid dynamics assessments are made by analysis, from lumped parameter modeling through unsteady computational fluid dynamics (CFD); testing, which can be cold flow or hot fire; or a combination of analysis and testing. Integration of all discipline methods into one branch enables efficient and accurate support to the projects. To accomplish this work, the branch currently employs approximately fifty engineers divided into four teams -- Propellant Delivery CFD, Combustion Driven Flows CFD, Unsteady and Experimental Flows, and Acoustics and Stability. This discussion will highlight some of the work performed in the branch and the direction in which the branch is headed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M12-2122 , M12-2111 , Advances in Rocket Engine Modeling and Simulation, and its Future; 26-27 Sept. 2012; Tokyo; Japan
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  • 36
    Publication Date: 2019-07-27
    Description: There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M11-1336 , M12-1855 , M12-1962
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  • 37
    Publication Date: 2019-07-27
    Description: A review of recently published coupled radiation and ablation capabilities involving the simulation of hypersonic flowfields relevant to Earth, Mars, or Venus entry is presented. The three fundamental mechanisms of radiation coupling are identified as radiative cooling, precursor photochemistry, and ablation-radiation interaction. The impact of these mechanisms are shown to be significant for a 3 m radius sphere entering Earth at hypothetical Mars return conditions (approximately 15 km/s). To estimate the influence precursor absorption on the radiative flux for a wide range of conditions, a simplified approach is developed that requires only the non-precursor solution. Details of a developed coupled ablation approach, which is capable of treating both massively ablating flowfields in the sublimation regime and weakly ablating diffusion Climited oxidation cases, are presented. A review of the two primary uncoupled ablation approximations, identified as the blowing correction and film coefficient approximations, is made and their impact for Earth and Mars entries is shown to be significant for recession and convective heating predictions. Fully coupled ablation and radiation simulations are presented for the Mars return sphere throughout its entire trajectory. Applying to the Mars return sphere the Pioneer- Venus heritage carbon phenolic heatshield, which has properties available in the open literature, the differences between steady state ablation and coupling to a material response code are shown to be significant.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-16461 , Radiation and Gas-Surface Interaction Phenomena in High Speed Re-Entry; 6-8- May 2013; Rhode-St-Genese; Belgium
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  • 38
    Publication Date: 2019-07-27
    Description: The traditional design and analysis practice for advanced propulsion systems relies heavily on expensive full-scale prototype development and testing. Over the past decade, use of high-fidelity analysis and design tools such as CFD early in the product development cycle has been identified as one way to alleviate testing costs and to develop these devices better, faster and cheaper. In the design of advanced propulsion systems, CFD plays a major role in defining the required performance over the entire flight regime, as well as in testing the sensitivity of the design to the different modes of operation. Increased emphasis is being placed on developing and applying CFD models to simulate the flow field environments and performance of advanced propulsion systems. This necessitates the development of next generation computational tools which can be used effectively and reliably in a design environment. The turbomachinery simulation capability presented here is being developed in a computational tool called Loci-STREAM [1]. It integrates proven numerical methods for generalized grids and state-of-the-art physical models in a novel rule-based programming framework called Loci [2] which allows: (a) seamless integration of multidisciplinary physics in a unified manner, and (b) automatic handling of massively parallel computing. The objective is to be able to routinely simulate problems involving complex geometries requiring large unstructured grids and complex multidisciplinary physics. An immediate application of interest is simulation of unsteady flows in rocket turbopumps, particularly in cryogenic liquid rocket engines. The key components of the overall methodology presented in this paper are the following: (a) high fidelity unsteady simulation capability based on Detached Eddy Simulation (DES) in conjunction with second-order temporal discretization, (b) compliance with Geometric Conservation Law (GCL) in order to maintain conservative property on moving meshes for second-order time-stepping scheme, (c) a novel cloud-of-points interpolation method (based on a fast parallel kd-tree search algorithm) for interfaces between turbomachinery components in relative motion which is demonstrated to be highly scalable, and (d) demonstrated accuracy and parallel scalability on large grids (approx 250 million cells) in full turbomachinery geometries.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M12-1951
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  • 39
    Publication Date: 2019-06-28
    Description: The trajectories of droplets in the air flowing past NACA 65(1)-208 airfoil and an NACA 65(1)-212 airfoil, both at an angle of attack of 4 degrees, were determined. The amount of water in droplet form impinging on the airfoils, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface affected were calculated from the trajectories and are presented. The amount, extent, and rate of impingement of the NACA 65(1)-208 airfoil are compared with the results for the NACA 65(1)1-212 airfoil. Under similar conditions of operation, the NACA 65(1)-208 airfoil collects less water than the NACA 65(1)-212 airfoil. The extent of impingement on the upper surface of the NACA 65(1)-208 airfoil is much less than on the upper surface of the NACA 65(1)-212 airfoil, but on the lower surface the extents of impingement are about the same.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2952
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  • 40
    Publication Date: 2019-07-19
    Description: Capillary rise in tubes, channels, and grooves has received significant attention in the literature for over 100 years. In yet another incremental extension of such work, a transient capillary rise problem is solved for spontaneous flow along an interconnected array of open channels forming what is referred to as an 'open-star' section. This geometry possesses several attractive characteristics including passive phase separations and high diffusive gas transport. Despite the complex geometry, novel and convenient approximations for capillary pressure and viscous resistance enable closed form predictions of the flow. As part of the solution, a combined scaling approach is applied that identifies unsteady-inertial-capillary, convective-inertial-capillary, and visco-capillary transient regimes in a single parameter. Drop tower experiments are performed employing 3-D printed conduits to corroborate all findings.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-31794 , Annual Meeting of the American Physical Society Division of Fluid Dynamics; Nov 23, 2014 - Nov 25, 2014; San Francisco, CA; United States
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  • 41
    Publication Date: 2019-07-19
    Description: The SPHERES Slosh Experiment (SSE) is a free floating experimental platform developed for the acquisition of long duration liquid slosh data aboard the International Space Station (ISS). The data sets collected will be used to benchmark numerical models to aid in the design of rocket and spacecraft propulsion systems. Utilizing two SPHERES Satellites, the experiment will be moved through different maneuvers designed to induce liquid slosh in the experiment's internal tank. The SSE has a total of twenty-four thrusters to move the experiment. In order to design slosh generating maneuvers, a parametric study with three maneuvers types was conducted using the General Moving Object (GMO) model in Flow-30. The three types of maneuvers are a translation maneuver, a rotation maneuver and a combined rotation translation maneuver. The effectiveness of each maneuver to generate slosh is determined by the deviation of the experiment's trajectory as compared to a dry mass trajectory. To fully capture the effect of liquid re-distribution on experiment trajectory, each thruster is modeled as an independent force point in the Flow-3D simulation. This is accomplished by modifying the total number of independent forces in the GMO model from the standard five to twenty-four. Results demonstrate that the most effective slosh generating maneuvers for all motions occurs when SSE thrusters are producing the highest changes in SSE acceleration. The results also demonstrate that several centimeters of trajectory deviation between the dry and slosh cases occur during the maneuvers; while these deviations seem small, they are measureable by SSE instrumentation.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: KSC-2013-352 , 2013 Flow-3D World Users Conference; Sep 18, 2013 - Sep 19, 2013; Chicago, IL; United States
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  • 42
    Publication Date: 2019-07-19
    Description: This paper describes the development and testing of a scalable thermal control architecture for instruments, subsystems, or systems that must operate in severe space environments with wide variations in sink temperature. The architecture is comprised by linking one or more hot-side variable conductance heat pipes (VCHPs) in series with one or more cold-side loop heat pipes (LHPs). The VCHPs provide wide area heat acquisition, limited distance thermal transport, modest against gravity pumping, concentrated LHP startup heating, and high switching ratio variable conductance operation. The LHPs provide localized heat acquisition, long distance thermal transport, significant against gravity pumping, and high switching ratio variable conductance operation. Combining two variable conductance devices in series ensures very high switching ratio isolation from severe environments like the Earth's moon, where each lunar day spans 15 Earth days (270 K sink, with a surface-shielded/space viewing radiator) and each lunar night spans 15 Earth days (80-100 K radiative sink, depending on location). The single VCHP-single LHP system described herein was developed to maintain thermal control of International Lunar Network (ILN) anchor node lander electronics, but it is also applicable to other variable heat rejection space missions in severe environments. The LHPVCHP system utilizes a stainless steel wire mesh wick ammonia VCHP, a Teflon wick propylene LHP, a pair of one-third square meter high radiators (one capillary-pumped horizontal radiator and a second gravity-fed vertical radiator), a half-meter of transport distance, and a wick-bearing co-located flow regulator (CLFR) to allow operation with a hot (deactivated) radiator. The VCHP was designed with a small reservoir formed by extending the length of its stainless steel heat pipe tubing. The system was able to provide end-to-end switching ratios of 300-500 during thermal vacuum testing at ATK, including 3-5 W/K ON conductance and 0.01 W/K OFF conductance. The test results described herein also include an in-depth analysis of VCHP condenser performance to explain VCHP switching operation in detail. Future multi-VCHP/multi-LHP thermal management system concepts that provide scalability to higher powers/longer transport lengths are also discussed in the paper.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M12-2277 , International Conference on Environmental Systems-(ICES); Jul 14, 2013 - Jul 18, 2013; Vail, CO; United States
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  • 43
    Publication Date: 2019-07-19
    Description: This talk reviews the predictions of gasdynamic, magnetohydrodynamic, and kinetic models for the magnetosheath and foreshock and compares these predictions with observations by the recent Cluster and THEMIS missions. Topics of interest include: the depletion layer, dawn/dusk asymmetries, the transmission of solar wind discontinuities, the formation of hot flow anomalies and cavities in the foreshock, and flows accelerated by field-line tension. We conclude by discussing opportunities for magnetosheath imaging.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Geospace Environment Modeling (GEM) 2010 Summer Workshop; Jun 20, 2010 - Jun 25, 2010; Snowmass, CO; United States
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  • 44
    Publication Date: 2019-07-19
    Description: The Fire Cartridge is a packed bed air filter with two different and separate layers of media designed to provide respiratory protection from combustion products after a fire event on the International Space Station (ISS). The first layer of media is a carbon monoxide catalyst made from gold nanoparticles dispersed on iron oxide. The second layer of media is universal carbon, commonly used in commercial respirator filters. Each layer must be optimally packed to effectively remove contaminants from the air. Optimal packing is achieved by vibratory agitations. However, if post-packing movement of the media within the cartridge occurs, mixing of the bed layers, air voids, and channeling could cause preferential air flow and allow contaminants to pass. Several iterations of prototype fire cartridges were developed to reduce post-packing movement of the media within each layer (settling), and to prevent mixing of the two media types. Both types of movement of the media contribute to decreased fire cartridge performance. Each iteration of the fire cartridge design was tested to demonstrate mechanical loads required to cause detrimental movement within the bed, and resulting level of functionality of the media beds after movement was detected. In order to optimally pack each layer, vertical, horizontal, and orbital agitations were tested and a final packed bulk density was calculated for each method. Packed bulk density must be calculated for each lot of catalyst to accommodate variations in particle size, shape, and density. In addition, a physical divider sheet between each type of media was added within the fire cartridge design to further inhibit intermixing of the bed layers.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22217 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR
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  • 45
    Publication Date: 2019-07-19
    Description: NASA?s Constellation Program included the Orion, Altair, and Lunar Surface Systems project offices. The first two elements, Orion and Altair, were planned to be manned space vehicles while the third element was much broader and included several sub-elements including Rovers and a Lunar Habitat. The planned missions involving these systems and vehicles included several risks and design challenges. Due to the unique thermal operating environment, many of these risks and challenges were associated with the vehicles? thermal control system. NASA?s Exploration Technology Development Program (ETDP) consisted of several technology development projects. The project chartered with mitigating the aforementioned thermal risks and design challenges was the Thermal Control System Development for Exploration Project. These risks and design challenges were being addressed through a rigorous technology development process that was planned to culminate with an integrated thermal control system test. Although these Constellation elements have been cancelled or significantly changed, the thermal technology development process is being continued within a new program entitled Enabling Technology Development and Demonstration (ETDD). The current paper summarizes the development efforts being performed by the technology development project. The development efforts involve heat acquisition and heat rejection hardware including radiators, heat exchangers, and evaporators. The project has also been developing advanced phase change material heat sinks and performing a material compatibility assessment for a promising thermal control system working fluid. The to-date progress and lessons-learned from these development efforts will be discussed throughout the paper.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22249 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 46
    Publication Date: 2019-07-19
    Description: Future EVA suits need processes and systems to control internal temperature and humidity without venting water to the environment. This paper describes an absorption-based cooling and dehumidification system as well as laboratory demonstrations of the key processes. There are two main components in the system: an evaporation cooling and dehumidification garment (ECDG) that removes both sensible heat and latent heat from the pressure garment, and an absorber radiator that absorbs moisture and rejects heat to space by thermal radiation. This paper discusses the overall design of both components, and presents recent data demonstrating their operation. We developed a design and fabrication approach to produce prototypical heat/water absorbing elements for the ECDG, and demonstrated by test that these elements could absorb heat and moisture at a high flux. Proof-of-concept tests showed that an ECDG prototype absorbs heat and moisture at a rate of 85 W/ft under conditions that simulate operation in an EVA suit. The heat absorption was primarily due to direct absorption of water vapor. It is possible to construct large, flexible, durable cooling patches that can be incorporated into a cooling garment with this system. The proof-of-concept test data was scaled to calculate area needed for full metabolic loads, thus showing that it is feasible to use this technology in an EVA suit. Full-scale, lightweight absorber/radiator modules have also been built and tested. They can reject heat at a flux of 33 W/ft while maintaining ECDG operation at conditions that will provide a cool and dry environment inside the EVA suit.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22046 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 47
    Publication Date: 2019-07-19
    Description: Phase change materials (PCM) may be useful for thermal control systems that involve cyclical heat loads or cyclical thermal environments such as Low Earth Orbit (LEO) and Low Lunar Orbit (LLO). Thermal energy can be stored in the PCM during peak heat loads or in adverse thermal environments. The stored thermal energy can then be released later during minimum heat loads or in more favorable thermal environments. One advantage that PCM s have over evaporators in this scenario is that they do not use a consumable. The use of water as a PCM rather than the more traditional paraffin wax has the potential for significant mass reduction since the latent heat of formation of water is approximately 70% greater than that of wax. One of the potential drawbacks of using ice as a PCM is its potential to rupture its container as water expands upon freezing. In order to develop a space qualified ice PCM heat exchanger, failure mechanisms must first be understood. Therefore, a methodical experimental investigation has been undertaken to demonstrate and document specific failure mechanisms due to ice expansion in the PCM. A number of ice PCM heat exchangers were fabricated and tested. Additionally, methods for controlling void location in order to reduce the risk of damage due to ice expansion were investigated. This paper presents the results of testing that occurred from March through September of 2010 and builds on testing that occurred during the previous year.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22153 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 48
    Publication Date: 2019-07-19
    Description: Sublimators have been proposed and used in spacecraft for heat rejection. Sublimators are desirable heat rejection devices for short duration use because they can transfer large amounts of heat using little mass and are self-regulating devices. Sublimators reject heat into space by freezing water inside a porous substrate, allowing it to sublimate into vapor, and finally venting it into space. The state of the art thermal control system in orbiting spacecraft is a two loop, two fluid system. The external coolant loop typically uses a toxic single phase fluid that acquires heat from the spacecraft and rejects most of it via a radiator. The sublimator functions as a transient topper for orbiting spacecraft during day pass periods when radiator efficiency decreases. The sublimator interfaces with the internal loop through a built in heat exchanger. The internal loop fluid is non-toxic and is typically a propylene glycol and water solution with inhibitors to prevent corrosion with aluminum fins of the heat exchangers. Feedwater is supplied from a separate line to the sublimator to maintain temperature control of the cabin and vehicle hardware. Water membrane evaporators have been developed for spacecraft and spacesuits. They function similar to a sublimator but require a backpressure valve which could be actuated for this application with a simple fully open or fully closed modes. This technology would be applied to orbital thermal control (lunar or planetary). This paper details a trade study showing that evaporators would greatly reduce the consumable that is used, effectively wasted, by sublimators during start up and shut down during the topping phases of each orbit. State of the art for 9 kW sublimators reject about 870 W per kilogram of mass and 1150 W per liter of volume. If water with corrosion inhibitors is used the evaporators would be about 80% of the mass and volume of the equivalent system. The size and mass increases to about 110% if the internal fluid is 50% propylene glycol/50% water. The true benefit comes from the backpressure valve, that prevents the cyclical shutdown/startup loss of the sublimator and amounts to as much as 0.85 kg per orbit.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-22048 , 41st International Conference on Environmental Systems; Jul 17, 2011 - Jul 21, 2011; Portland, OR; United States
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  • 49
    Publication Date: 2019-07-19
    Description: We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-21631 , 2010 AGU Fall Meeting; 13?17 Dec. 2010; San Francisco, CA; United States
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  • 50
    Publication Date: 2019-07-19
    Description: Observations of the transport of magnetic elements across the Sun's surface indicate that, in general, the meridional flow extends all the way to the poles. Furthermore, the speed of this flow varies systematically over each solar cycle faster at minimum and slower at maximum. The flow speed on the approach to this (Cycle 24) minimum was substantially faster than it was at the last minimum. This increased flow speed should have produced a short Cycle 23 with strong polar fields in the flux transport dynamos used to predict Cycle 24. This is contrary to what we have seen. The increased flow speed does produce weak polar fields in the surface flux transport models like those used to estimate past irradiance variations. However, these surface flux transport models use meridional flow profiles that do not agree with the observations. Both types of flux transport models are missing identifiable components. We note that the observed changes in the structure of the meridional flow profile are consistent with Spruit's model for the torsional oscillations - suggesting that there may be associated irradiance variations.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M10-0366 , 2010 SORCE Science Meeting; May 19, 2010 - May 21, 2010; Keystone, CO; United States
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  • 51
    Publication Date: 2019-07-13
    Description: It is known that the adverse effects of shock wave boundary layer interactions in high speed inlets include reduced total pressure recovery and highly distorted flow at the aerodynamic interface plane (AIP). This paper presents a design method for flow control which creates perturbations in geometry. These perturbations are tailored to change the flow structures in order to minimize shock wave boundary layer interactions (SWBLI) inside supersonic inlets. Optimizing the shape of two dimensional micro-size bumps is shown to be a very effective flow control method for two-dimensional SWBLI. In investigating the three dimensional SWBLI, a square duct is employed as a baseline. To investigate the mechanism whereby the geometric elements of the baseline, i.e. the bottom wall, the sidewall and the corner, exert influence on the flow's aerodynamic characteristics, each element is studied and optimized separately. It is found that arrays of micro-size bumps on the bottom wall of the duct have little effect in improving total pressure recovery though they are useful in suppressing the incipient separation in three-dimensional problems. Shaping sidewall geometry is effective in re-distributing flow on the side wall and results in a less distorted flow at the exit. Subsequently, a near 50% reduction in distortion is achieved. A simple change in corner geometry resulted in a 2.4% improvement in total pressure recovery.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2013-3653 , AIAA Applied Aerodynamics Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 52
    Publication Date: 2019-07-13
    Description: An experiment investigating flow and heat transfer of long (length to diameter ratio of 18) cylindrical film cooling holes has been completed. In this paper, the thermal field in the flow and on the surface of the film cooled flat plate is presented for nominal freestream turbulence intensities of 1.5 and 8 percent. The holes are inclined at 30 deg above the downstream direction, injecting chilled air of density ratio 1.0 onto the surface of a flat plate. The diameter of the hole is 0.75 in. (approx. 0.02 m) with center to center spacing (pitch) of 3 hole diameters. Coolant was injected into the mainstream flow at nominal blowing ratios of 0.5, 1.0, 1.5, and 2.0. The Reynolds number of the freestream was approximately 11,000 based on hole diameter. Thermocouple surveys were used to characterize the thermal field. Infrared thermography was used to determine the adiabatic film effectiveness on the plate. Hotwire anemometry was used to provide flowfield physics and turbulence measurements. The results are compared to existing data in the literature. The aim of this work is to produce a benchmark dataset for Computational Fluid Dynamics (CFD) development to eliminate the effects of hole length to diameter ratio and to improve resolution in the near-hole region. In this report, a Time Filtered Navier Stokes (TFNS), also known as Partially Resolved Navier Stokes (PRNS), method that was implemented in the Glenn-HT code is used to model coolant-mainstream interaction. This method is a high fidelity unsteady method that aims to represent large scale flow features and mixing more accurately.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-662718 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 53
    Publication Date: 2019-07-13
    Description: An experimental and computational study was conducted to evaluate the performance and emissions characteristics of a candidate Lean Direct Injection (LDI) combustor configuration with a mix of simplex and airblast injectors. The National Combustion Code (NCC) was used to predict the experimentally measured EINOx emissions for test conditions representing low power, medium power, and high-power engine cycle conditions. Of the six cases modeled with the NCC using a reduced-kinetics finite-rate mechanism and lagrangian spray modeling, reasonable predictions of combustor exit temperature and EINOx were obtained at two high-power cycle conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Propulsion and Energy Forum 2014; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 54
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-662711 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 55
    Publication Date: 2019-07-13
    Description: Repeated Test 1 extinction tests near the upward flammability limit are expected to follow a Poisson process trend. This Poisson process trend suggests that rather than define a ULOI and MOC (which requires two limits to be determined), it might be better to define a single upward limit as being where 1/e (where e (approx. equal to 2.7183) is the characteristic time of the normalized Poisson process) of the materials burn, or, rounding, where approximately 1/3 of the samples fail the test (and burn). Recognizing that spacecraft atmospheres will not bound the entire oxygen-pressure parameter space, but actually lie along the normoxic atmosphere control band, we can focus the materials flammability testing along this normoxic band. A Normoxic Upward Limiting Pressure (NULP) is defined that determines the minimum safe total pressure for a material within the constant partial pressure control band. Then, increasing this pressure limit by a factor of safety, we can define the material as being safe to use at the NULP + SF (where SF is on the order of 10 kilopascal, based on existing flammability data). It is recommended that the thickest material to be tested with the current Test 1 igniter should be 3 mm thick (1/8 inches) to avoid the problem of differentiating between an ignition limit and a true flammability limit.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ICES-2014-179 , GRC-E-DAA-TN13759 , International Conference on Environmental Systems (ICES 2014); Jul 13, 2014 - Jul 17, 2014; Tuscon, AZ; United States
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  • 56
    Publication Date: 2019-07-13
    Description: Cryogenic Storage &Transfer are enabling propulsion technologies in the direct path of nearly all future human or robotic missions; It is identified by NASA as an area with greatest potential for cost saving; This proposal aims at resolving fundamental scientific issues behind the engineering development of the storage tanks; We propose to use the ISS lab to generate & collect archival scientific data:, raise our current state-of-the-art understanding of transport and phase change issues affecting the storage tank cryogenic fluid management (CFM), develop and validate state-of-the-art CFD models to innovate, optimize, and advance the future engineering designs
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN18539 , American Society for Gravitational and Space Research (ASGSR) Annual Meeting; Oct 22, 2014 - Oct 26, 2014; Pasadena, CA; United States
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  • 57
    Publication Date: 2019-07-13
    Description: It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M14-3774 , AIChE (American Institute of Chemical Engineers) Annual Meeting; Nov 16, 2014 - Nov 21, 2014; Atlanta, GA; United States
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  • 58
    Publication Date: 2019-07-13
    Description: The concept of temperature control of an electronic component using a single Loop Heat Pipe (LHP) is well established for Aerospace applications. Using two LHPs is often desirable for redundancy/reliability reasons or for increasing the overall heat source-sink thermal conductance. This effort elaborates on temperature controlling operation of a thermal system that includes two small ammonia LHPs thermally coupled together at the evaporator end as well as at the condenser end and operating "in parallel". A transient model of the LHP system was developed on the Thermal Desktop (TradeMark) platform to understand some fundamental details of such parallel operation of the two LHPs. Extensive thermal-vacuum testing was conducted with two thermally coupled LHPs operating simultaneously as well as with only one LHP operating at a time. This paper outlines the temperature control procedures for two LHPs operating simultaneously with widely varying sink temperatures. The test data obtained during the thermal-vacuum testing, with both LHPs running simultaneously in comparison with only one LHP operating at a time, are presented with detailed explanations.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GSFC-E-DAA-TN19620 , Frontiers in Heat Pipes (FHP) ; 5; 9; 013009
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  • 59
    Publication Date: 2019-07-13
    Description: The Constrained Vapor Bubble (CVB) is a wickless, grooved heat pipe and we report on a full- scale fluids experiment flown on the International Space Station (ISS). The CVB system consists of a relatively simple setup a quartz cuvette with sharp corners partially filled with either pentane or an ideal mixture of pentane and isohexane as the working fluids. Along with temperature and pressure measurements, the two-dimensional thickness profile of the menisci formed at the corners of the quartz cuvette was determined using the Light Microscopy Module (LMM). Even with the large, millimeter dimensions of the CVB, interfacial forces dominate in these exceedingly small Bond Number systems. The experiments were carried out at various power inputs. Although conceptually simple, the transport processes were found to be very complex with many different regions. At the heated end of the CVB, due to a high temperature gradient, we observed Marangoni flow at some power inputs. This region from the heated end to the central drop region is defined as a Marangoni dominated region. We present a simple analysis based on interfacial phenomena using only measurements from the ISS experiments that lead to a predictive equation for the thickness of the film near the heated end of the CVB. The average pressure gradient for flow in the film is assumed due to the measured capillary pressure at the two ends of the liquid film and that the pressure stress gradient due to cohesion self adjusts to a constant value over a distance L. The boundary conditions are the no slip condition at the wall interface and an interfacial shear stress at the liquid- vapor interface due to the Marangoni stress, which is due to the high temperature gradient. Although the heated end is extremely complex, since it includes three- dimensional variations in radiation, conduction, evaporation, condensation, fluid flow and interfacial forces, we find that using the above simplifying assumptions, a simple successful model can be developed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN19372 , American Society for Gravitational and Space Research Annual Meeting 2014; Oct 22, 2014 - Oct 26, 2014; Pasadena, CA; United States
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  • 60
    Publication Date: 2019-07-13
    Description: Numerical simulations of fluid flow and collection efficiency for a Science Engineering Associates (SEA) multi-element probe are presented. Simulation of the flow field was produced using the Glenn-HT Navier-Stokes solver. Three-dimensional unsteady results were produced and then time averaged for the heat transfer and collection efficiency results. Three grid densities were investigated to enable an assessment of grid dependence. Simulations were completed for free stream velocities ranging from 85-135 meters per second, and free stream total pressure of 44.8 and 93.1 kilopascals (6.5 and 13.5 pounds per square inch absolute). In addition, the effect of angle of attack and yaw were investigated by including 5 degree deviations from straight for one of the flow conditions. All but one of the cases simulated a probe in isolation (i.e. in a very large domain without any support strut). One case is included which represents a probe mounted on a support strut within a finite sized wind tunnel. Collection efficiencies were generated, using the LEWICE3D code, for four spherical particle sizes, 100, 50, 20, and 5 micron in diameter. It was observed that a reduction in velocity of about 20% occurred, for all cases, as the flow entered the shroud of the probe. The reduction in velocity within the shroud is not indicative of any error in the probe measurement accuracy. Heat transfer results are presented which agree quite well with a correlation for the circular cross section heated elements. Collection efficiency results indicate a reduction in collection efficiency as particle size is reduced. The reduction with particle size is expected, however, the results tended to be lower than the previous results generated for isolated two-dimensional elements. The deviation from the two-dimensional results is more pronounced for the smaller particles and is likely due to the reduced flow within the protective shroud. As particle size increases differences between the two-dimensional and three dimensional results become negligible. Taken as a group, the total collection efficiency of the elements including the effects of the shroud has been shown to be in the range of 0.93 to 0.99 for particles above 20 microns. The 3D model has improved the estimated collection efficiency for smaller particles where errors in previous estimates were more significant.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN15066 , AIAA Aviation and Aeronautics Forum and Exposition (Aviation 2014); Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 61
    Publication Date: 2019-07-13
    Description: This paper presents a steady-state thermal model of a hot-wire instrument applicable to atmospheric measurement of water content in clouds. In this application, the power required to maintain the wire at a given temperature is used to deduce the water content of the cloud. The model considers electrical resistive heating, axial conduction, convection to the flow, radiation to the surroundings, as well as energy loss due to the heating, melting, and evaporation of impinging liquid and or ice. All of these parameters can be varied axially along the wire. The model further introduces a parameter called the evaporation potential which locally gauges the maximum fraction of incoming water that evaporates. The primary outputs of the model are the steady-state power required to maintain a spatially-average constant temperature as well as the variation of that temperature and other parameters along the wire. The model is used to understand the sensitivity of the hot-wire performance to various flow and boundary conditions including a detailed comparison of dry air and wet (i.e. cloud-on) conditions. The steady-state power values are compared to experimental results from a Science Engineering Associates (SEA) Multi-Element probe, a commonly used water-content measurement instrument. The model results show good agreement with experiment for both dry and cloud-on conditions with liquid water content. For ice, the experimental measurements under read the actual water content due to incomplete evaporation and splashing. Model results, which account for incomplete evaporation, are still higher than experimental results where the discrepancy is attributed to splashing mass-loss which is not accounted in the model.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN15563 , (AVIATION 2014) AIAA Aviation and Aeronautics Forum and Exposition; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 62
    Publication Date: 2019-07-13
    Description: A simulation toolbox has been developed for the creation of both steady-state and dynamic thermodynamic software models. This presentation describes the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS), which combines generic thermodynamic and controls modeling libraries with a numerical iterative solver to create a framework for the development of thermodynamic system simulations, such as gas turbine engines. The objective of this presentation is to present an overview of T-MATS, the theory used in the creation of the module sets, and a possible propulsion simulation architecture.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN16854 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 63
    Publication Date: 2019-07-13
    Description: Subsonic and supersonic aircraft concepts proposed by NASAs Fundamental Aeronautics Program have integrated propulsion systems with asymmetric nozzles. The asymmetry in the exhaust of these propulsion systems creates asymmetric flow and acoustic fields. The flow asymmetries investigated in the current study are from two parallel round, 2:1, and 8:1 aspect ratio rectangular jets at the same nozzle conditions. The flow field was measured with streamwise and cross-stream particle image velocimetry (PIV). A large dataset of single and twin jet flow field measurements was acquired at subsonic jet conditions. The effects of twin jet spacing and forward flight were investigated. For round, 2:1, and 8:1 rectangular twin jets at their closest spacings, turbulence levels between the two jets decreased due to enhanced jet mixing at near static conditions. When the flight Mach number was increased to 0.25, the flow around the twin jet model created a velocity deficit between the two nozzles. This velocity deficit diminished the effect of forward flight causing an increase in turbulent kinetic energy relative to a single jet. Both of these twin jet flow field effects decreased with increasing twin jet spacing relative to a single jet. These variations in turbulent kinetic energy correlate with changes in far-field sound pressure level.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN16376 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 64
    Publication Date: 2019-07-13
    Description: A thermal design concept of attaching the thermoelectric cooler (TEC) hot side directly to the radiator and maximizing the number of TECs to cool multiple detectors in space is presented. It minimizes the temperature drop between the TECs and radiator. An ethane constant conductance heat pipe transfers heat from the detectors to a TEC cold plate which the cold side of the TECs is attached to. This thermal design concept minimizes the size of TEC heat rejection systems. Hence it reduces the problem of accommodating the radiator within a required envelope. It also reduces the mass of the TEC heat rejection system. Thermal testing of a demonstration unit in vacuum verified the thermal performance of the thermal design concept.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GSFC-E-DAA-TN15640 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States|International Energy Conversion Engineering Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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  • 65
    Publication Date: 2019-07-13
    Description: Nuclear power provides an enabling capability for NASA missions that might otherwise be constrained by power availability, mission duration, or operational robustness. NASA and the Department of Energy (DOE) are developing fission power technology to serve a wide range of future space uses. Advantages include lower mass, longer life, and greater mission flexibility than competing power system options. Kilowatt-class fission systems, designated "Kilopower," were conceived to address the need for systems to fill the gap above the current 100-Wclass radioisotope power systems being developed for science missions and below the typical 100-kWe-class reactor power systems being developed for human exploration missions. This paper reviews the current fission technology project and examines some Kilopower concepts that could be used to support future science missions or human precursors.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2013-216541 , E-18719 , NETS-2013-6814 , GRC-E-DAA-TN7326 , Nuclear and Emerging Technologies for Space; Feb 25, 2013 - Feb 28, 2013; Albuquerque, NM; Mexico
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  • 66
    Publication Date: 2019-07-13
    Description: Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and flexibility to fit around columns of various shapes and sizes. ECVT is also safer than other commonly used imaging modalities as it operates in the range of low frequencies (1 MHz) and does not radiate radioactive energy. In this effort, ECVT is being used to image flow parameters in a packed bed reactor for an ISS flight experiment.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN11755 , American Society for Gravitational and Space Research Meeting; Nov 03, 2013 - Nov 08, 2013; Orlando, FL; United States|International Symposium for Physical Sciences in Space; Nov 03, 2013 - Nov 08, 2013; Orlando, FL; United States
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  • 67
    Publication Date: 2019-07-13
    Description: Air plasma radiation in Local Thermodynamic Equilibrium (LTE) within cylindrical geometries is studied with an application towards modeling the radiative transfer inside arc-constrictors, a central component of constricted-arc arc jets. A detailed database of spectral absorption coefficients for LTE air is formulated using the NEQAIR code developed at NASA Ames Research Center. The database stores calculated absorption coefficients for 1,051,755 wavelengths between 0.04 m and 200 m over a wide temperature (500K to 15 000K) and pressure (0.1 atm to 10.0 atm) range. The multi-group method for spectral reduction is studied by generating a range of reductions including pure binning and banding reductions from the detailed absorption coefficient database. The accuracy of each reduction is compared to line-by-line calculations for cylindrical temperature profiles resembling typical profiles found in arc-constrictors. It is found that a reduction of only 1000 groups is sufficient to accurately model the LTE air radiation over a large temperature and pressure range. In addition to the reduction comparison, the cylindrical-slab formulation is compared with the finite-volume method for the numerical integration of the radiative flux inside cylinders with varying length. It is determined that cylindrical-slabs can be used to accurately model most arc-constrictors due to their high length to radius ratios.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper-2013-3142 , ARC-E-DAA-TN10084 , AIAA CFD Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 68
    Publication Date: 2019-07-13
    Description: An investigation on dynamic-stall suppression capabilities of combustion-powered actuation (COMPACT) applied to a tabbed VR-12 airfoil is presented. In the first section, results from computational fluid dynamics (CFD) simulations carried out at Mach numbers from 0.3 to 0.5 are presented. Several geometric parameters are varied including the slot chordwise location and angle. Actuation pulse amplitude, frequency, and timing are also varied. The simulations suggest that cycle-averaged lift increases of approximately 4% and 8% with respect to the baseline airfoil are possible at Mach numbers of 0.4 and 0.3 for deep and near-deep dynamic-stall conditions. In the second section, static-stall results from low-speed wind-tunnel experiments are presented. Low-speed experiments and high-speed CFD suggest that slots oriented tangential to the airfoil surface produce stronger benefits than slots oriented normal to the chordline. Low-speed experiments confirm that chordwise slot locations suitable for Mach 0.3-0.4 stall suppression (based on CFD) will also be effective at lower Mach numbers.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-18571 , American Helicopter Society (AHS) Annual Forum; May 20, 2014 - May 22, 2014; Montreal; Canada
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  • 69
    Publication Date: 2019-07-13
    Description: Progress on an experimental study of laminar-to-turbulent transition induced by an isolated roughness element in a supersonic laminar boundary layer is reported in this paper. Here, the primary focus is on the effects of roughness planform shape on the instability and transition characteristics. Four different roughness planform shapes were considered (a diamond, a circle, a right triangle, and a 45 degree fence) and the height and width of each one was held fixed so that a consistent frontal area was presented to the oncoming boundary layer. The nominal roughness Reynolds number was 462 and the ratio of the roughness height to the boundary layer thickness was 0.48. Detailed flow- field surveys in the wake of each geometry were performed via hot-wire anemometry. High- and low-speed streaks were observed in the wake of each roughness geometry, and the modified mean flow associated with these streak structures was found to support a single dominant convective instability mode. For the symmetric planform shapes - the diamond and circular planforms - the instability characteristics (mode shapes, growth rates, and frequencies) were found to be similar. For the asymmetric planform shapes - the right-triangle and 45 degree fence planforms - the mode shapes were asymmetrically distributed about the roughness-wake centerline. The instability growth rates for the asymmetric planforms were lower than those for the symmetric planforms and therefore, transition onset was delayed relative to the symmetric planforms.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2014-2501 , NF1676L-17666 , AIAA Fluid Dynamics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 70
    Publication Date: 2019-07-13
    Description: The effects of forward- and backward-facing steps on the receptivity and stability of three-dimensional supersonic boundary layers over a swept wing with a blunt leading edge are numerically investigated for a freestream Mach number of 3 and a sweep angle of 30 degrees. The flow fields are obtained by solving the full Navier-Stokes equations. The evolution of instability waves generated by surface roughness is simulated with and without the forward- and backward-facing steps. The separation bubble lengths are about 5-10 step heights for the forward-facing step and are about 10 for the backward-facing step. The linear stability calculations show very strong instability in the separated region with a large frequency domain. The simulation results show that the presence of backward-facing steps decreases the amplitude of the stationary crossflow vortices with longer spanwise wavelengths by about fifty percent and the presence of forward-facing steps does not modify the amplitudes noticeably across the steps. The waves with the shorter wavelengths grow substantially downstream of the step in agreement with the linear stability prediction.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2014-2639 , NF1676L-17654 , AIAA Fluid Dynamics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 71
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    In:  CASI
    Publication Date: 2019-07-13
    Description: Updated information on the status of the UH-60A Airloads wind tunnel test data, including recent work performed by NASA.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN10902 , Airloads Workshop; Aug 21, 2013; College Park, Maryland; United States
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  • 72
    Publication Date: 2019-07-13
    Description: A formulation for the discontinuous Galerkin (DG) method that leads to solutions using the differential form of the equation (as opposed to the standard integral form) is presented. The formulation includes (a) a derivative calculation that involves only data within each cell with no data interaction among cells, and (b) for each cell, corrections to this derivative that deal with the jumps in fluxes at the cell boundaries and allow data across cells to interact. The derivative with no interaction is obtained by a projection, but for nodal-type methods, evaluating this derivative by interpolation at the nodal points is more economical. The corrections are derived using the approximate (Dirac) delta functions. The formulation results in a family of schemes: different approximate delta functions give rise to different methods. It is shown that the current formulation is essentially equivalent to the flux reconstruction (FR) formulation. Due to the use of approximate delta functions, an energy stability proof simpler than that of Vincent, Castonguay, and Jameson (2011) for a family of schemes is derived. Accuracy and stability of resulting schemes are discussed via Fourier analyses. Similar to FR, the current formulation provides a unifying framework for high-order methods by recovering the DG, spectral difference (SD), and spectral volume (SV) schemes. It also yields stable, accurate, and economical methods.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2014-218135 , E-18938 , International Conference on Spectral and High-Order Methods (ICOSAHOM) 2014; Jun 23, 2014 - Jun 27, 2014; Salt Lake City, UT; United States
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  • 73
    Publication Date: 2019-07-13
    Description: Thus far, studies of gaseous diffusion flames on the International Space Station (ISS) have been limited to research conducted in the Microgravity Science Glovebox (MSG) in mid-2009 and early 2012. The research was performed with limited instrumentation, but novel techniques allowed for the determination of the soot temperature and volume fraction. Development is now underway for the next experiments of this type. The Advanced Combustion via Microgravity Experiments (ACME) project consists of five independent experiments that will be conducted with expanded instrumentation within the stations Combustion Integrated Rack (CIR). ACMEs goals are to improve our understanding of flame stability and extinction limits, soot control and reduction, oxygen-enriched combustion which could enable practical carbon sequestration, combustion at fuel lean conditions where both optimum performance and low emissions can be achieved, the use of electric fields for combustion control, and materials flammability. The microgravity environment provides longer residence times and larger length scales, yielding a broad range of flame conditions which are beneficial for simplified analysis, e.g., of limit behaviour where chemical kinetics are important. The detailed design of the modular ACME hardware, e.g., with exchangeable burners, is nearing completion, and it is expected that on-orbit testing will begin in 2016.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN13358 , 2014 Spring Technical Meeting of the Central States Section of The Combustion Institute; Mar 16, 2014 - Mar 18, 2014; Tulsa, OK; United States
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  • 74
    Publication Date: 2019-07-13
    Description: The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield. To better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process would be beneficial. Here, a technique developed at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products in a hypersonic flow is applied. Although high-temperature ablation is difficult and expensive to recreate in a laboratory environment, low-temperature sublimation creates a limited physics problem that can be used to explore ablation-product transport in a hypersonic flow-field. In the current work, a subscale capsule reentry vehicle model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel. The PLIF technique provides images of the spatial distribution of sublimated naphthalene in the heat-shield boundary layer, separated shear layer, and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. PLIF images have shown high concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. It was shown that, in general, the capsule shear layer appears to be more unsteady at lower angels of attack. The PLIF images demonstrated that during a wind tunnel run, as the model heated up, the rate of naphthalene ablation increased, since the PLIF signal increased steadily over the course of a run. Additionally, the shear layer became increasingly unsteady over the course of a wind tunnel run, likely because of increased surface roughness but also possibly because of the increased blowing. Regions with a relatively low concentration of naphthalene were also identified in the capsule backshell recirculation region and are most likely the result of cross-flow-induced vortices on the capsule afterbody.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper-2014-1152 , NF1676L-16749 , AIAA Aerospace Sciences Meeting; Jan 13, 2014 - Jan 17, 2014; National Harbor, MD; United States
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  • 75
    Publication Date: 2019-07-13
    Description: Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development. Currently there is no fully coupled computational tool to analyze this fluid/structure interaction process. The objective of this study was to develop a fully coupled aeroelastic modeling capability to describe the fluid/structure interaction process during the transient nozzle operations. The aeroelastic model composes of three components: the computational fluid dynamics component based on an unstructured-grid, pressure-based computational fluid dynamics formulation, the computational structural dynamics component developed in the framework of modal analysis, and the fluid-structural interface component. The developed aeroelastic model was applied to the transient nozzle startup process of the Space Shuttle Main Engine at sea level. The computed nozzle side loads and the axial nozzle wall pressure profiles from the aeroelastic nozzle are compared with those of the published rigid nozzle results, and the impact of the fluid/structure interaction on nozzle side loads is interrogated and presented.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M13-2490 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit; Jul 15, 2013 - Jul 17, 2013; San Jose, CA; United States
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  • 76
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Paper ICCFD7-1201 , ARC-E-DAA-TN5790 , 7th International Conference on Computational Fluid Dynamics; Jul 09, 2012 - Jul 13, 2012; Big Island, HI; United States
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  • 77
    Publication Date: 2019-07-13
    Description: The overall goal of this study was achieved: Replicated the numerical assessment performed by Chen et. al. (2005). Displayed the ability of Thermal Desktop to be coupled with thermo-electrochemical analysis techniques. such that the local heat generated on the cells is a function of the model itself using logic blocks and arrays. Differences in the TD temperature vs. depth of discharge profiles and Chen's was most likely due to differences in two primary areas: Contact regions and conductance values. Differences in density and specific heat values. center dot The model results are highly dependent on the accuracy of the material properties with respect to the multiple layers of an individual cell.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-29125 , Thermal & Fluids Analysis Workshop (TFAWS) 2013; Jul 29, 2013 - Aug 02, 2013; KSC, FL; United States
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  • 78
    Publication Date: 2019-07-13
    Description: The turbulent flows through a plane channel and a channel with a constriction (2-D hill) are numerically simulated using DNS and RANS calculations. The Navier-Stokes equations in the DNS are solved using a higher order kinetic energy preserving central schemes and a fifth order accurate upwind biased WENO scheme for the space discretization. RANS calculations are performed using the NASA code CFL3D with the komega SST two-equation model and a full Reynolds stress model. Using DNS, the magnitudes of different terms that appear in the enstrophy equation are evaluated. The results show that the dissipation and the diffusion terms reach large values at the wall. All the vortex stretching terms have similar magnitudes within the buffer region. Beyond that the triple correlation among the vorticity and strain rate fluctuations becomes the important kinematic term in the enstrophy equation. This term is balanced by the viscous dissipation. In the separated flow, the triple correlation term and the viscous dissipation term peak locally and balance each other near the separated shear layer region. These findings concur with the analysis of Tennekes and Lumley, confirming that the energy transfer terms associated with the small-scale dissipation and the fluctuations of the vortex stretching essentially cancel each other, leaving an equation for the dissipation that is governed by the large-scale motion.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-16595 , AIAA Fluid Dynamics Conference and Exhibit; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 79
    Publication Date: 2019-07-13
    Description: Over the past decade, there has been much progress towards improved phenomenological modeling and algorithmic updates for the direct simulation Monte Carlo (DSMC) method, which provides a probabilistic physical simulation of gas Rows. These improvements have largely been based on the work of the originator of the DSMC method, Graeme Bird. Of primary importance are improved chemistry, internal energy, and physics modeling and a reduction in time to solution. These allow for an expanded range of possible solutions In altitude and velocity space. NASA's current production code, the DSMC Analysis Code (DAC), is well-established and based on Bird's 1994 algorithms written in Fortran 77 and has proven difficult to upgrade. A new DSMC code is being developed in the C++ programming language using object-oriented and data-oriented design paradigms to facilitate the inclusion of the recent improvements and future development activities. The development efforts on the new code, the Multiphysics Algorithm with Particles (MAP), are described, and performance comparisons are made with DAC.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2014-2546 , NF1676L-17733 , AIAA/ASME Joint Thermophysics and Heat Transfer Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
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  • 80
    Publication Date: 2019-07-13
    Description: Simulation of turbulent flows with shocks employing explicit subgrid-scale (SGS) filtering may encounter a loss of accuracy in the vicinity of a shock. In this work we perform a comparative study of different approaches to reduce this loss of accuracy within the framework of the dynamic Germano SGS model. One of the possible approaches is to apply Harten's subcell resolution procedure to locate and sharpen the shock, and to use a one-sided test filter at the grid points adjacent to the exact shock location. The other considered approach is local disabling of the SGS terms in the vicinity of the shock location. In this study we use a canonical shock-turbulence interaction problem for comparison of the considered modifications of the SGS filtering procedure. For the considered test case both approaches show a similar improvement in the accuracy near the shock.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN17606 , International Conference on Computational Fluid Dynamics (ICCFD8); Jul 14, 2014 - Jul 18, 2014; Chengdu; China
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  • 81
    Publication Date: 2019-07-13
    Description: The functional equivalence of the unstructured grid code FUN3D to the the structured grid code LAURA (Langley Aerothermodynamic Upwind Relaxation Algorithm) is documented for applications of interest to the Entry, Descent, and Landing (EDL) community. Examples from an existing suite of regression tests are used to demonstrate the functional equivalence, encompassing various thermochemical models and vehicle configurations. Algorithm modifications required for the node-based unstructured grid code (FUN3D) to reproduce functionality of the cell-centered structured code (LAURA) are also documented. Challenges associated with computation on tetrahedral grids versus computation on structured-grid derived hexahedral systems are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-15629 , AIAA Computational Fluid Dynamics Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 82
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN8721 , ARC-E-DAA-TN8722 , ASTRONUM - 2013. 8th International Conference on Numerical Modeling of Space Plasma Flows; Jul 01, 2013 - Jul 05, 2013; Biarritz; France|AIAA Computational Fluid Dynamics Conference; Jun 24, 2013 - Jun 27, 2013; San Diego, CA; United States
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  • 83
    Publication Date: 2019-07-13
    Description: The fully implicit ablation and thermal response code simulates pyrolysis and ablation of thermal protection materials and systems. The governing equations, which include energy conservation, a three-component decomposition model, and a surface energy balance, are solved with a moving grid.This work describes new modeling capabilities that are added to a special version of code. These capabilities include a time-dependent pyrolysis gas flow momentum equation with Darcy-Forchheimer terms and pyrolysis gas species conservation equations with finite rate homogeneous chemical reactions. The total energy conservation equation is also enhanced for consistency with these new additions. Two groups of parametric studies of the phenolic impregnated carbon ablator are performed. In the first group, an Orion flight environment for a proposed lunar-return trajectory is considered. In the second group, various test conditions for arcjet models are examined. The central focus of these parametric studies is to understand the effect of pyrolysis gas momentum transfer on material in-depth thermal responses with finite-rate, equilibrium, or frozen homogeneous gas chemistry. Results indicate that the presence of chemical nonequilibrium pyrolysis gas flow does not significantly alter the in-depth thermal response performance predicted using the chemical equilibrium gas model.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN8881 , Journal of Spacecraft and Rockets; 50; 2; 256-269
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  • 84
    Publication Date: 2019-07-13
    Description: Detached-eddy simulation (DES) based on the v(sup 2)-f Reynolds-averaged Navier-Stokes (RANS) model is developed and tested. The v(sup 2)-f model incorporates the anisotropy of near-wall turbulence which is absent in other RANS models commonly used in the DES community. The v(sup 2)-f RANS model is modified in order the proposed v(sup 2)-f-based DES formulation reduces to a transport equation for the subgrid-scale kinetic energy isotropic turbulence. First, three coefficients in the elliptic relaxation equation are modified, which is tested in channel flows with friction Reynolds number up to 2000. Then, the proposed v(sup 2)-f DES model formulation is derived. The constant, C(sub DES), required in the DES formulation was calibrated by simulating both decaying and statistically-steady isotropic turbulence. After C(sub DES) was calibrated, the v(sub 2)-f DES formulation is tested for flow around a circular cylinder at a Reynolds number of 3900, in which case turbulence develops after separation. Simulations indicate that this model represents the turbulent wake nearly as accurately as the dynamic Smagorinsky model. Spalart-Allmaras-based DES is also included in the cylinder flow simulation for comparison.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN5786 , 7th International Conference on Computational Fluid Dynamics (ICCFD7); Jul 09, 2012 - Jul 13, 2012; Big Island, HI; United States
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  • 85
    Publication Date: 2019-07-13
    Description: With the era of full utilization of the ISS now upon us, this presentation will discuss some of the highest-priority areas for two-phase flow systems with thermal control applications. These priorities are guided by recommendations of a 2011 NRC Decadal Survey report, Recapturing a Future for Space Exploration, Life and Physical Sciences for a New Era as well as an internal NASA exercise in response to the NRC report conducted in early 2012. Many of these proposals are already in various stages of development, while others are still conceptual.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN9131 , Interagency Advanced Power Group Workshop; May 02, 2013; Cleveland, OH; United States
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  • 86
    Publication Date: 2019-07-13
    Description: Thin Film Heat Flux Sensors: Design and Methodology: (1) Heat flux is one of a number of parameters, together with pressure, temperature, flow, etc. of interest to engine designers and fluid dynamists, (2) The measurement of heat flux is of interest in directly determining the cooling requirements of hot section blades and vanes, and (3)In addition, if the surface and gas temperatures are known, the measurement of heat flux provides a value for the convective heat transfer coefficient that can be compared with the value provided by CFD codes.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN9169 , International Instrumentation Symposium 59th; May 13, 2013 - May 17, 2013; Cleveland, OH; United States
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  • 87
    Publication Date: 2019-07-13
    Description: Upward flame spread experiments were conducted on a thin fabric cloth consisting of 75% cotton and 25% fiberglass. The sample is sandwiched symmetrically with stainless steel plates with the exposed width varying between 2 to 8.8 cm from test to test and 〉1.5m tall. The bottom edge was ignited resulting in a symmetric two sided flame. For the narrower samples (. 5cm), two sided flame growth would proceed until reaching some limiting value (15-30 cm depending on sample width). Fluctuation or instability of the flame base on one side would initially become visible and then the flame base would retreat downstream and cause extinguishment on one side. Detailed examination of the still images shows that the fuel continues to vaporize from the extinguished side due to the thermally thin nature of the fuel. But, due to the remaining inert fiberglass mesh, which acts as a flashback arrestor, the extinguished side was not able to be reignited by the remaining flame. The remaining flame would then shrink in length due to the reduced heat transfer to the solid to a shorter length. The one-sided flame will spread stably with a constant speed and a constant flame length to the end of the sample. A constant length flame implies that the pyrolysis front and the burnt out fronts move at the same speed. For the wider samples (. 7cm), no one-sided extinction is observed. Two-sided flames spread all the way to the top of the sample. For these wider widths, the flames are still growing and have not reached their limiting length if it exists. Care was taken to minimize the amount of non-symmetries in the experimental configuration. Repeated tests show that blow-off can occur on either side of the sample. The flame growth is observed to be very symmetric during the growth phase and grew to significant length (〉10cm) before extinction of the flame on one side. Our proposed explanation of this unusual phenomenon (i.e. stronger two ]sided flame cannot exist but weaker one-sided flame can) is as follows: The observed one-sided extinction is a blow- off induced by buoyant entrainment. It is known that the flammable diffusion flame regime is bounded by quenching and blow ]off limits when varying incoming air velocity. The narrowest samples tested (between 2 and 5 cm) begin within the flammable range, but as the flame grows, the buoyancy driven air velocity increases at the neighborhood of the flame base. The initially stable flame crosses the extinguishment boundary resulting in a flame blow-off. When one-side of the flame extinguishes, the remaining side shrinks due to the reduced heat transfer to the solid. This reduces the induced velocity and the flame becomes stable. It is proposed that this may have implications to upward flame growth beyond this experiment.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Paper-070LT-0331 , GRC-E-DAA-TN8437 , U.S. National Combustion Meeting; May 19, 2013 - May 22, 2013; Vail, CO; United States
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  • 88
    Publication Date: 2019-07-13
    Description: The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (T(sub e)), electron number density (n(sub e)) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with T(sub e) approx. = (3 - 12 eV and n(sub e) approx. = 10(exp 12) - 10(exp 14)/cu cm.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN9116 , 44th AIAA Plasmadynamics and Lasers Conference; Jun 23, 2012; San Diego, CA; United States
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  • 89
    Publication Date: 2019-07-13
    Description: This work uses a discontinuous-Galerkin spectral-element method (DGSEM) to solve the compressible Navier-Stokes equations [1{3]. The inviscid ux is computed using the approximate Riemann solver of Roe [4]. The viscous fluxes are computed using the second form of Bassi and Rebay (BR2) [5] in a manner consistent with the spectral-element approximation. The method of lines with the classical 4th-order explicit Runge-Kutta scheme is used for time integration. Results for polynomial orders up to p = 15 (16th order) are presented. The code is parallelized using the Message Passing Interface (MPI). The computations presented in this work are performed using the Sandy Bridge nodes of the NASA Pleiades supercomputer at NASA Ames Research Center. Each Sandy Bridge node consists of 2 eight-core Intel Xeon E5-2670 processors with a clock speed of 2.6Ghz and 2GB per core memory. On a Sandy Bridge node the Tau Benchmark [6] runs in a time of 7.6s.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN9710 , 2nd International Workshop on Higher-Order CFD Methods; May 27, 2013 - May 28, 2013; Cologne; Germany
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  • 90
    Publication Date: 2019-07-13
    Description: Thermal protection materials and systems (TPS) protect vehicles from the heat generated when entering a planetary atmosphere. NASA has developed many TPS systems over the years for vehicle ranging from planetary probes to crewed vehicles. The goal for all TPS is efficient and reliable performance. Efficient means using the right material for the environment and minimizing the mass of the heat shield without compromising safety. Efficiency is critical if the payload such as science experiments is to be maximized on a particular vehicle. Reliable means that we understand and can predict performance of the material. Although much characterization and testing of materials is performed to qualify and certify them for flight, it is not possible to completely recreate the reentry conditions in test facilities, and flight-testing
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN9472 , Loughborough University Seminar; Jun 13, 2013; Loughborough; United Kingdom
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  • 91
    Publication Date: 2019-07-13
    Description: Analysis tools are needed to investigate aerodynamic performance of Variable-Speed Power Turbines (VSPT) for rotorcraft applications. The VSPT operates at low Reynolds numbers (transitional flow) and over a wide range of incidence. Previously, the capability of a published three-equation turbulence model to predict accurately the transition location for three-dimensional heat transfer problems was assessed. In this paper, the results of a post-diction exercise using a three-dimensional flow in a transonic linear cascade comprising VSPT blading are presented. The measured blade pressure distributions and exit total pressure and flow angles for two incidence angles corresponding to cruise (i = 5.8deg) and takeoff (i = -36.7deg) were used for this study. For the higher loading condition of cruise and the negative incidence condition of takeoff, overall agreement with data may be considered satisfactory but areas of needed improvement are also indicated.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2013-217860 , E-18653 , GT2013-95030 , ASME International Gas Turbine Institute (IGTI) Turbo Expo 2013; Jun 03, 2013 - Jun 07, 2013; San Antonio, TX; United States
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  • 92
    Publication Date: 2019-07-13
    Description: The goal of this study was to assess the impacts of free water propagation in the Waste and Hygiene Compartment (WHC) installed in Node 3. Free water can be generated inside the WHC in small quantities due to crew hygiene activity. To mitigate potential impact of free water in Node 3 cabin the WHC doorway is enclosed by a waterproof bump-out, Kabin, with openings at the top and bottom. At the overhead side of the rack, there is a screen that prevents large drops of water from exiting. However, as the avionics fan in the WHC causes airflow toward the deck side of the rack, small quantities of free water may exit at the bottom of the Kabin. A Computational Fluid Dynamics (CFD) analysis of Node 3 cabin airflow enable identifying the paths of water transport. To simulate the droplet transport the Lagrangian discrete phase approach was used. Various initial droplet distributions were considered in the study. The droplet diameter was varied in the range of 5-20 mm. The results of the computations showed that most of the drops fall to the rack surface not far from the WHC curtain.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: JSC-CN-28461 , 43rd International Conference on Environmental Systems; Jul 14, 2013 - Jul 18, 2013; Vail, CO; United States
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  • 93
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ASME 6th International Conference on Energy Sustainability; Jul 23, 2012 - Jul 26, 2012; San Diego, CA; United States
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  • 94
    Publication Date: 2019-07-13
    Description: Five different central difference schemes, based on a conservative differencing form of the Kennedy and Gruber skew-symmetric scheme, were compared with six different upwind schemes based on primitive variable reconstruction and the Roe flux. These eleven schemes were tested on a one-dimensional acoustic standing wave problem, the Taylor-Green vortex problem and a turbulent channel flow problem. The central schemes were generally very accurate and stable, provided the grid stretching rate was kept below 10%. As near-DNS grid resolutions, the results were comparable to reference DNS calculations. At coarser grid resolutions, the need for an LES SGS model became apparent. There was a noticeable improvement moving from CD-2 to CD-4, and higher-order schemes appear to yield clear benefits on coarser grids. The UB-7 and CU-5 upwind schemes also performed very well at near-DNS grid resolutions. The UB-5 upwind scheme does not do as well, but does appear to be suitable for well-resolved DNS. The UF-2 and UB-3 upwind schemes, which have significant dissipation over a wide spectral range, appear to be poorly suited for DNS or LES.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M13-2383 , 51st AIAA Aerospace Sciences Meeting; Jan 07, 2013 - Jan 10, 2013; Grapevine, TX
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  • 95
    Publication Date: 2019-07-13
    Description: A Presentation is given on Modeling Contact Line Dynamics in Evaporating Menisci.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-18594 , GRC-E-DAA-TN6657 , Comsol User''s Conference; Oct 03, 2012 - Oct 05, 2012; Boston, MA; United States
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  • 96
    Publication Date: 2019-07-13
    Description: Demagnetization temperature of a linear alternator (LA) can be accurately predicted through an analytical Maxwell model. The M-H characteristics of the alternator magnets must be known. Vendor data are given for cube-shaped magnets, and the shape of a LA magnet may affect its magnetic properties. At GRC, M-H data are directly measured for each LA magnet. This method was validated using TDC alternator tests on the Alternator Test Rig. The analytical Maxwell modeling was utilized on a different style linear alternator to predict demagnetization temperatures for the Advanced Stirling Convertor.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-17823-1 , International Energy Conversion Engineering Conference (IECEC) 2011; Jul 31, 2011 - Aug 03, 2011; San Diego, CA; United States
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  • 97
    Publication Date: 2019-07-13
    Description: This study demonstrates that coupling of a material thermal response code and a flow solver using finite-rate gas/surface interaction model provides time-accurate solutions for multidimensional ablation of carbon based charring ablators. The material thermal response code used in this study is the Two-dimensional Implicit Thermal Response and Ablation Program (TITAN), which predicts charring material thermal response and shape change on hypersonic space vehicles. Its governing equations include total energy balance, pyrolysis gas momentum conservation, and a three-component decomposition model. The flow code solves the reacting Navier-Stokes equations using Data Parallel Line Relaxation (DPLR) method. Loose coupling between material response and flow codes is performed by solving the surface mass balance in DPLR and the surface energy balance in TITAN. Thus, the material surface recession is predicted by finite-rate gas/surface interaction boundary conditions implemented in DPLR, and the surface temperature and pyrolysis gas injection rate are computed in TITAN. Two sets of gas/surface interaction chemistry between air and carbon surface developed by Park and Zhluktov, respectively, are studied. Coupled fluid-material response analyses of stagnation tests conducted in NASA Ames Research Center arc-jet facilities are considered. The ablating material used in these arc-jet tests was a Phenolic Impregnated Carbon Ablator (PICA). Computational predictions of in-depth material thermal response and surface recession are compared with the experimental measurements for stagnation cold wall heat flux ranging from 107 to 1100 Watts per square centimeter.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E--DAA-TN4377 , 43nd AIAA Thermophysics Conference; Jun 25, 2012 - Jun 28, 2012; New Orleans, LA; United States
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  • 98
    Publication Date: 2019-07-13
    Description: The unsteady convective flow effects in a transonic compressor rotor with a circumferential-groove casing treatment are investigated in this paper. Experimental results show that the circumferential-groove casing treatment increases the compressor stall margin by almost 50% for the current transonic compressor rotor. Steady flow simulation of the current casing treatment, however, yields only a 15% gain in stall margin. The flow field at near-stall operation is highly unsteady due to several self-induced flow phenomena. These include shock oscillation, vortex shedding at the trailing edge, and interaction between the passage shock and the tip clearance vortex. The primary focus of the current investigation is to assess the effects of flow unsteadiness and unsteady flow convection on the circumferential-groove casing treatment. Unsteady Reynolds-averaged Navier-Stokes (URANS) and Large Eddy Simulation (LES) techniques were applied in addition to steady Reynolds-averaged Navier-Stokes (RANS) to simulate the flow field at near-stall operation and to determine changes in stall margin. The current investigation reveals that unsteady flow effects are as important as steady flow effects on the performance of the circumferential grooves casing treatment in extending the stall margin of the current transonic compressor rotor. The primary unsteady flow mechanism is unsteady flow injection from the grooves into the main flow near the casing. Flows moving into and out of the grooves are caused due to local pressure difference near the grooves. As the pressure field becomes transient due to self-induced flow oscillation, flow injection from the grooves also becomes unsteady. The unsteady flow simulation shows that this unsteady flow injection from the grooves is substantial and contributes significantly to extending the compressor stall margin. Unsteady flows into and out of the grooves have as large a role as steady flows in the circumferential grooves. While the circumferential-groove casing treatment seems to be a steady flow device, unsteady flow effects should be included to accurately assess its performance as the flow is transient at near-stall operation.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GT2012-68411 , E-18398 , ASME Turbo Expo; Jun 11, 2012 - Jun 15, 2012; Copenhagen; Denmark
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  • 99
    Publication Date: 2019-07-13
    Description: Turbine blades in rocket and jet engine turbomachinery experience enormous harmonic loading conditions. These loads result from the integer number of upstream and downstream stator vanes as well as the other turbine stages. The standard technique for forced response analysis to assess structural integrity is to decompose a CFD generated flow field into its harmonic components, and to then perform a frequency response analysis at the problematic natural frequencies. Recent CFD analysis and water-flow testing at NASA/MSFC, though, indicates that this technique may miss substantial harmonic and non-harmonic excitation sources that become present in complex flows. These complications suggest the question of whether frequency domain analysis is capable of capturing the excitation content sufficiently. Two studies comparing frequency response analysis with transient response analysis, therefore, have been performed. The first is of a bladed disk with each blade modeled by simple beam elements. It was hypothesized that the randomness and other variation from the standard harmonic excitation would reduce the blade structural response, but the results showed little reduction. The second study was of a realistic model of a bladed-disk excited by the same CFD used in the J2X engine program. The results showed that the transient analysis results were up to 10% higher for "clean" nodal diameter excitations and six times larger for "messy" excitations, where substantial Fourier content around the main harmonic exists.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M12-1667 , 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dyamics, and Materials Conference; Apr 23, 2012 - Apr 27, 2012; Honolulu, HI; United States
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  • 100
    Publication Date: 2019-07-13
    Description: Several experiments have been performed in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue University. A 7 degree half angle cone at 6 degree angle of attack with temperature-sensitive paint (TSP) and PCB pressure transducers was tested under quiet flow. The stationary crossflow vortices appear to break down to turbulence near the lee ray for sufficiently high Reynolds numbers. Attempts to use roughness elements to control the spacing of hot streaks on a flared cone in quiet flow did not succeed. Roughness was observed to damp the second-mode waves in areas influenced by the roughness, and wide roughness spacing allowed hot streaks to form between the roughness elements. A forward-facing cavity was used for proof-of-concept studies for a laser perturber. The lowest density at which the freestream laser perturbations could be detected was 1.07 x 10(exp -2) kilograms per cubic meter. Experiments were conducted to determine the transition characteristics of a streamwise corner flow at hypersonic velocities. Quiet flow resulted in a delayed onset of hot streak spreading. Under low Reynolds number flow hot streak spreading did not occur along the model. A new shock tube has been built at Purdue. The shock tube is designed to create weak shocks suitable for calibrating sensors, particularly PCB-132 sensors. PCB-132 measurements in another shock tube show the shock response and a linear calibration over a moderate pressure range.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-14883 , 42nd AIAA Fluid Dynamics Conference and Exhibit; Jun 25, 2012 - Jun 28, 2012; New Orleans, LA; United States
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