Дисертації: "Blunt body"

1

Dominy, Robert Gerald. "Rarefied hypersonic shock wave and blunt body flows." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47034.

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2

Castledine, Andre J. "Investigation of the fluid flow around blunt body samplers." Thesis, University of Leeds, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305756.

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3

Ess, Peter. "Numerical simulation of blunt body-generated detonation wave ramjet flowfields." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ45873.pdf.

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4

Jain, Sunny. "Hypersonic nonequilibrium flow simulations over a blunt body using bgk simulations." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2406.

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5

Ess, Peter. "Numerical simulation of blunt-body generated detonation waves in viscous hypersonic ducted flows." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288263.

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6

Johnson, Joshua E. "Multidisciplinary optimization of non-spherical, blunt-body heat shields for a planetary entry vehicle." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3766.

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Thesis (M.S.) -- University of Maryland, College Park, 2006.
Thesis research directed by: Dept. of Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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7

Johnson, Joshua E. "Aerothermodynamic optimization of earth entry blunt body heat shields for lunar and Mars return." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9177.

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Thesis (Ph.D.) -- University of Maryland, College Park, 2009.
Thesis research directed by: Dept. of Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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8

Aubuchon, Vanessa V. "Damping Effects of Drogue Parachutes on Orion Crew Module Dynamics." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23327.

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Currently, simulation predictions of the Orion Crew Module (CM) dynamics with drogue parachutes deployed are under-predicting the amount of damping as seen in free-flight tests. The Apollo Legacy Chute Damping model has been resurrected and applied to the Orion system. The legacy model has been applied to predict CM damping under drogue parachutes for both Vertical Spin Tunnel free flights and the Pad Abort-1 flight test. Comparisons between the legacy Apollo prediction method and test data are favorable. A key hypothesis in the Apollo legacy drogue damping analysis is that the drogue parachutes\' net load vector aligns with the CM drogue attachment point velocity vector. This assumption seems reasonable and produces good results, but has never been experimentally verified. The wake of the CM influences the drogue parachutes, which makes performance predictions of the parachutes difficult. Many of these effects are not currently modeled in the simulations.

A forced oscillation test of the CM with parachutes was conducted in the NASA LaRC 20-Ft Vertical Spin Tunnel (VST) to gather additional data to validate and refine the Apollo legacy drogue model. A second loads balance was added to the original Orion VST model to measure the drogue parachute loads independently of the CM. The objective of the test was to identify the contribution of the drogues to CM damping and provide additional information to quantify wake effects and the interactions between the CM and parachutes. The drogue parachute force vector was shown to be highly dependent on the CM wake characteristics. Based on these wind tunnel test data, the Apollo Legacy Chute Damping model was determined to be a sufficient approximation of the parachute dynamics in relationship to the CM dynamics for preliminary entry vehicle system design. More wake effects should be included to better model the system. These results are being used to improve simulation model fidelity of CM flight with drogues deployed, which has been identified by the project as key to a successful Orion Critical Design Review.
Master of Science

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9

Kurits, Inna. "Quantitative global heat-transfer measurements using temperaure-sensitive [sic] paint on a blunt body in hypersonic flows." College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8302.

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Thesis (M.S.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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10

Pinn, Jarred Michael. "Effect of End-Plate Tabs on Drag Reduction of a 3D Bluff Body with a Blunt Base." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/698.

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This thesis involves the experimental testing of a bluff body with a blunt base to evaluate the effectiveness of end-plate tabs in reducing drag. The bluff body is fitted with interchangeable end plates; one plate is flush with the rest of the exterior and the other plate has small tabs protruding perpendicularly into the flow. The body is tested in the Cal Poly 3ft x 4ft low speed wind tunnel. Testing is conducted in three phases. The first phase was the hot-wire measurement of streamwise velocity of the near wake behind the bluff body. An IFA300 thermal anemometry system with a hot-wire probe placed behind the model measures the wake velocity fluctuations. The power spectral density on the model without tabs shows large spikes at Strouhal numbers of 0.266, 0.300, and 0.287 at corresponding Re = 41,400, 82,800, 124,200 where vortex shedding occurs. The model with tabs shows no such peaks in power and therefore has attenuated vortex generation in the wake flow at that location. The second phase of testing was pressure testing the model through the use of pressure ports on the exterior of the bluff body. A Scanivalve pressure transducer measured multiple ports almost simultaneously through tubing that was connected to the model internally and routed through the model’s strut mount and outside of the wind tunnel. This pressure testing shows that the model with tabs is able to achieve up to 36% increase in Cp at Reh = 41,400 on the base region of the bluff body and no negative pressure spikes that occur as a result of vortex shedding. The last phase of testing is the measurement of total drag on the model through a sting balance mount. This testing shows that the drag on the model is reduced by 14% at Re = 41,400. However it also shows that as velocity increased, the drag reduction is reduced and ultimately negated at Re = 124,200 with no drag loss at all. The addition of tabs as a passive flow control device did eliminate vortex shedding and alter the base pressure of the bluff body. This particular model however showed no reduction in total drag on the model at high Reynolds numbers higher than 124,000. Further study is necessary to isolate the exact geometry and flow velocities that should be able to produce more favorable drag results for a bluff body with this type of passive flow control device.

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11

Erlhoff, Ethan Bruce. "Distributed Forcing on a 3D Bluff Body with a Blunt Base, An Experimental Active Drag Control Approach." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/879.

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This paper seeks to explore the effects of an active drag control method known as distributed forcing on a 3D bluff body with a blunt base. The 9.5 x 15.25 x 3 inch aluminum model constructed for this experiment has an elliptically shaped nose and rectangular aft section. The model is fitted with four, 12 Volt fans, forcing the freestream air into and out of 1 mm thick slots on the upper and lower trailing edges. The forcing is steady in time, held at a constant forcing velocity though all Reynolds numbers, but varies roughly sinusoidally in the spanwise direction across the model. Testing was conducted at Reynolds numbers of 50,000, 100,000 and 150,000 at California Polytechnic State University, San Luis Obispo in the Aerospace Engineering Department’s subsonic 3’ by 4’ wind tunnel. Effectiveness of the distributed forcing method was evaluated by measuring the base pressure on the model using a Scanivalve system. By measuring multiple static pressure ports, it was found that base pressure increased by 15.3% and 4.2% at Reynolds numbers of 50,000 and 100,000 respectively, and showed a decrease of 2.7% at a Reynolds number of 150,000. Total drag on the model was also measured using a sting balance mount fitted with strain gauges. This test showed a drag reduction of 15.8% and 5.5% for Reynolds numbers of 50,000 and 100,000 respectively, and an increase in drag of 2.0% at Reynolds number of 150,000, when omitting external power required to run the forcing assembly. The forcing assembly was shown to require nearly 12 times the power to operate than it saves in drag reduction at Reynolds number of 50,000. In addition, a thermal anemometry measurement of streamwise velocity of the near wake behind the bluff body was conducted to qualitatively assess the attenuation of the vortex street behind the model. Distributed forcing shows that as the freestream velocity is increased as compared to the forcing velocity, the change in energy spectral density is lessened, and as such, the largest attenuation in vortex shedding is at Reynolds number of 50,000 while nearly no change is seen at the Reynolds number of 150,000.

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12

Sevier, Abigail. "Feasibility Study for Testing the Dynamic Stability of Blunt Bodies with a Magnetic Suspension System in a Supersonic Wind Tunnel." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1493207020743959.

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13

Chen, Ru-Ching. "Development of a Supersonic Nozzle and Test Section for use with a Magnetic Suspension System for Re-Entry Aeroshell Models." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1544179612537658.

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14

Bracq, Anthony. "Contribution à la prédiction du risque lésionnel thoracique lors de chocs localisés à travers la caractérisation et la modélisation d'impacts balistiques non pénétrants." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0019/document.

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Depuis plusieurs décennies, l’évaluation des armes à létalité réduite (ALR) et des gilets pare-balles suscite l’intérêt majeur des forces de l’ordre autour du globe. En effet, ces armes présumées à létalité réduite ou non létales sont tenues d’occasionner uniquement une douleur suffisamment importante à un individu afin d’assurer sa neutralisation. Les gilets pare-balles, quant à eux, doivent garantir un certain niveau de protection pour réduire le risque de traumatismes lié à leur déformation dynamique. Le Centre de Recherche, d’Expertise et d’appui Logistique (CREL) du Ministère de l’Intérieur français a ainsi pour objectif le développement d’un outil de prédiction du risque lésionnel thoracique lors d’impacts balistiques non pénétrants. Cela permettrait alors d’évaluer les performances des ALR et des gilets pare-balles avant leur déploiement en théâtre d’opérations. Plus précisément, cette méthode doit uniquement être fondée sur la mesure directe du processus dynamique de déformation d’un bloc de gel synthétique soumis à un impact balistique. Pour répondre à ce besoin, l’approche numérique est considérée dans ces travaux de thèse par l’emploi du mannequin numérique du thorax humain HUByx comme un outil intermédiaire permettant la détermination de fonctions de transfert entre les mesures expérimentales sur un bloc de gel et le risque lésionnel. La reproduction de conditions d’impact réelles sur HUByx nécessite la caractérisation et la modélisation de projectiles ALR ainsi que de projectiles d’armes à feu et de gilets pare-balles. Elles reposent sur une procédure d’identification par méthode inverse appliquée à l’essai de Taylor pour la modélisation des ALR et à l’essai du cône dynamique d’enfoncement sur le bloc de gel pour celle du couple projectile/gilet pare-balles. Des travaux sont dédiés à la caractérisation mécanique et à la modélisation du gel synthétique sous sollicitations dynamiques. Enfin, une approche statistique basée sur des analyses de corrélation est introduite exploitant à la fois les mesures expérimentales, les données numériques ainsi que les rapports de cas de la littérature. Une cartographie du thorax associée au risque de fractures costales est établie et est uniquement fonction d’une mesure expérimentale
For decades, the assessment of less-lethal weapons (LLW) and bulletproof vests has generated major interest from law enforcement agencies around the world. Indeed, these presumed less-lethal or non-lethal weapons are required to cause only significant pain to an individual to ensure their neutralization. Bulletproof vests, in turn, must provide a certain level of protection to reduce the risk of trauma related to their dynamic deformation. The Center for Research, Expertise and Logistics Support (CREL) of the French Ministry of the Interior aims to develop a tool to predict thoracic injury risk during non-penetrating ballistic impacts. It would therefore be possible to evaluate the performance of LLW and bulletproof vests before their deployment in operations. More precisely, this method must only be based on the direct measurement of the dynamic process of deformation of a synthetic gel block subjected to a ballistic impact. To address that issue, the numerical approach is considered in this thesis by the use of the human thorax dummy HUByx as an intermediate tool for the determination of transfer functions between experimental metrics on a gel block and the risk of injury. The reproduction of real impact conditions on HUByx thus requires the characterization and modeling of less-lethal projectiles as well as projectiles of firearms and bulletproof vests. They rely on an inverse method identification procedure applied to the Taylor test for modeling LLW and on the analysis of blunt impacts on the gel block for projectiles/bulletproof vests. Work is then dedicated to the mechanical characterization and modeling of the synthetic gel under dynamic loadings. Finally, a statistical approach based on correlation analyses is introduced using both experimental measurements, numerical data as well as case reports from the literature. A thorax mapping associated with the risk of rib fractures is established and only depends on an experimental metric

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15

Meljordshagen, von Ubisch Ann Kristin. "BMI og sosiodemografiske faktorers påvirkning på operative forløsninger blant Norske og Pakistanske kvinner i Groruddalen, Norge." Thesis, Nordic School of Public Health NHV, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:norden:org:diva-3326.

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Bakgrunn: Økning i BMI og immigrasjon til Norge medfører nye utfordringer og det må settes fokus på å bekjempe ulikheter innen helse for mor og barn. I dag utgjør pakistanske immigranter en av de største minoritetsgruppene i Norge. Målet for denne studien er å undersøke forekomst av pregravid body mass index (BMI) og noen sosiodemografiske faktorers påvirkning på operative forløsninger (keisersnitt, vakuum, og tang) blant Norske og Pakistanske førstegangsfødende kvinner i Groruddalen, Norge. Metode: Populasjonsbasert kohort undersøkelse av 146 norske og 39 pakistanske kvinner som går til svangerskapskontroll på helsestasjoneri Groruddalen og deres fødsler ved Oslo universitetssykehusHF, Ullevål og Akershus universitetssykehus HF i Norge. Resultat: Pakistanske kvinner haddelavere pre-gravid BMI enn norske kvinner (22.1 og 24.6, p <0.05). En lavere andel pakistanske kvinner hadde utdannelse> 9år (79.5%) enn norske kvinner (96.6%, p<0.05) og en lavere andel arbeidet utenfor hjemmet, 66.5 % kontra 95.2%, p<0.05. I tillegg var pakistanske kvinneryngre (M=26.4, SD=4.0 år) sammenlignet med norske kvinner(M=29.7, SD=4.4 år, p<0.05). Nyfødte barn av pakistanske kvinnerveide 339 gram mindre, med en gjennomsnittlig fødselsvekt på 3181 gram,i forhold til de norske nyfødte på 3520 gram (p <0.05). Det varingen signifikant forskjell i operative forløsninger blant pakistanske kvinner med 31.6% og norske kvinnermed 27.9 %, p=0.805. Uavhengig av etnisitet hadde variabelen mors alder OR=1.106 (CI95:1.017 til 1.203) og svangerskapets lengde i dager OR= 0.951 (CI95:0.908 til 0.997) sammenheng med operative forløsninger i denne studien. Detnyfødte barnets vekt OR=1.001 (CI95:1.000 til 1.002) varmuligens et grensetilfelle. Konklusjon: Studien viser sosiodemografiske forskjeller mellom norske og pakistanske kvinner i Groruddalen, Norge. Pakistanske kvinner haddelavere BMI, lavere utdanningslengde, færrearbeidet utenfor hjemmet, de varyngre når de fødte sitt første barn og de fødtebarn med lavere vektenn norske kvinner. Det varikke forskjell i andel operative forløsninger mellom norske og pakistanske kvinner. Uavhengig av etnisitet haddekvinnenes alder og svangerskapets lengde påvirkning på operativ forløsning
Background: Elevated body mass index(BMI) and increased immigration pose challenges that demand a new focus on health inequalities for mothers and children. Currently, Pakistani immigrants are among the largest minority groups in Norway.This study aimed to determine the prevalence of pre-pregnancy BMI and the impact of different sociodemographic factors on operative (caesarean section, vacuum and forceps) deliveries among Norwegian and Pakistani nulliparous women in Groruddalen, Norway. Methods: This population-based cohort study included 146 Norwegian and 39 Pakistani women attending Child Health Clinics in Groruddalen and delivering at Oslo University Hospital and Ullevål and Akershus University Hospital, Norway. Results: Compared to Norwegian women, pre-pregnancy BMI was lower in Pakistani women (24.6 and 22.1, respectively; p < .05). Further, education level was > 9 years lower in Pakistani versus Norwegian women (79.5 % and 96.6 %, respectively; p < .05) and fewer Pakistani women work outside the home (66.5 % and 95.2 %, respectively; p < .05). Compared to Norwegian women (M = 29.7 years, SD = 4.4 years, p <.05), Pakistani women were younger (M = 26.4 years, SD = 4.0 years) when they delivered their first child. Moreover, Pakistani infants weighed 339 g less (average birth-weight = 3181 g) compared to Norwegian infants (3520 g; p< 0.05). We observed no significant difference in operative delivery among the Pakistaniversus Norwegian women (31.6 % and 27.9 %, respectively; p = 0.805). Regardless of ethnicity, variable maternal age (OR=1.106 [CI 95: 1.017 to 1.203]) and gestational age (OR=0.951 [CI 95: 0.908 to 0.997]) associated with operative delivery in this study.Newborn weight (OR=1.001 [CI 95: 1.000 to 1.002]) was considered borderline. Conclusion: This study revealedsociodemographic differences between Norwegian and Pakistani women undergoing operative delivery in Groruddalen, Norway. Compared to Norwegian women, Pakistani women had lower BMI and lower educational attainment. Fewer Pakistani women worked outside the home and they were younger when they delivered theirfirst child. Additionally, the birth weight of Pakistani babies delivered was lower than Norwegian newborns. We observed no difference in the proportion of operative deliveries between Norwegian and Pakistani women. Regardless of ethnicity, women’s chronological and gestational age affect operative delivery.

ISBN 978-91-86739-64-5

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16

Grønning, Stølen Svanhild Bjørg. "Inntakav vanlig brusog lettbrus og insidens av diabetes type 2 blant adventister i Nord-Amerika." Thesis, Nordic School of Public Health NHV, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:norden:org:diva-3634.

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Bakgrunn: Diabetes er globalt økende, og et voksende folkehelseproblem. Hovedårsakene er den raske økningen av fedme, fysisk inaktivitet og et økende antall eldre. Samtidig med økt inntakav sukker og kunstige søtningsstoffer, brus og lettbrus, har fedme og diabetestilfeller også økt. Hensikten med denne studien var å undersøke om det er en sammenheng mellom inntak av brus og lettbrus og insidensav diabetes type 2. Metode: Data ble samlet fra Adventist Health Study-2, en prospektiv kohortstudie. Data benyttet varbasert på et spørreskjema ved studiestart, og et oppfølgingsskjema, Hospital History Form(HHF-3). HHF-3 ble benyttetopptil 6 år senere med spørsmål om en evt. diabetesdiagnose, og tidspunkt for diagnosen. Deltakere med diabetes ved studiestart ble ekskludert. Antall deltakere i diabetesstudien var 45777. Nye diabetestilfeller under studien var 1277. Analysene ble gjort både med og uten kroppsmasseindeks (KMI). Det ble benyttet komplementær log-log-Cox analyse for å beregne hazard ratioer (HR) og tilhørende 95 % konfidensintervaller. Resultater: I multivariate analyser justert for demografiske variabler, KMI, type kosthold, fysisk aktivitet, inntak av fiberog magnesium, var inntak av≥1 boks ( = 355 ml) lettbrus daglig assosiert med insidens av diabetes type 2(HR=1,46, 95% CI, 1,19-1,78),p(trend)< 0,0001. Inntak av ≥ 1 boksvanlig brusdagligvar ikke forbundet med økt risiko for diabetes, (HR=1,20, 95 %Cl 0,95-1,50). Sammenhengene ble styrketog statistisk signifikant for begge typer brus når det ikke blejustert for KMI. Andre risikofaktorer for utvikling av diabetes var alder, mannlig kjønn, ikke-hvit etnisitet, og KMI. Et høyt magnesiuminntak, et høytfiberinntak, høyere utdanningog et vegetarisk kostholdvar beskyttende mot sykdommen. Konklusjon: Inntak av lettbrus men ikkevanlig brus,var signifikant assosiert med utvikling av diabetes type 2.
Background: Diabetes is increasing globally,presenting a growing public health problem. The rapid rise of obesity, physical inactivity, and an increasinglyelderly populationcontribute to this epidemic. The increase in obesity and diabetes coincide with increased intake of sugary and artificially sweetened drinks. Aim: This study aimed to investigate whether the consumption of regularor diet soft drinks predicts the incidence of type2 diabetes. Method: We used data collected from the Adventist Health Study-2, a prospective cohort study. The data was based on a baseline questionnaire, as well as a follow-up form (i.e., hospital history form-3) distributed to previous respondents up to 6 years later. Both questionnaire and follow-upformasked about a possible diabetes diagnosis and date of diagnosis. Importantly, Adventist Health Study-2 excluded individiuals who presented with diabetes at baseline. Among 45,777 subjects, the study detected 1,277 new cases of diabetes. Analyses were conducted both with and without body mass index. Complementary log-log Cox analysis was used to calculate hazard ratios(HR)and corresponding 95% confidence intervals. Results: Adjusted for demographic variables, body mass index, type of diet, physical activity, and fiber and magnesiumintake, multvariateanalysis showed that consumptionof ≥1 can (355 ml) of diet soda/day was associated with the incidence of type 2 diabetes (HR=1.46, 95% CI, 1.19 to 1.73;p<0.001). In comparison,consumptionof ≥ 1 can of regular soda/daydid not increaserisk of diabetes (HR = 1.20, 95% CI, 0.95 to 1.50). The associations were strengthened and statistically significant for both types of soda when not adjusted for BMI. Other risk factors for developing diabetes included age, male gender, non-white ethnicity, and body mass index. High intake of magnesiumandfiber, higher education,and a vegetarian diet were protective against the disease. Conclusion: Consumption of diet soda was significantly associated with the development of type 2 diabetes.

ISBN 978-91-982282-0-5

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17

Lin, Ching-ming, and 林慶銘. "Hypersonic Flow for Spiked Blunt-body with Vortex-ring." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/10592347946583881391.

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碩士
國立中央大學
機械工程學系
84
The technique of numerical method for simulating thehypersonic flow field of spiked blunt body with vortex-ring was studied in this work. The main numerical methodused here was finite volume method with TVD scheme andelliptic type body- fitted coordinate system. The resultshown that the vortex-ring will effect the flow field ofspiked blunt body and different ring-position will causedifferent flow type.

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18

Farzan, Farnaz. "Interaction of microwave filaments and blunt body in supersonic flow." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17467.

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19

Satheesh, K. "The Effect Of Energy Deposition In Hypersonic Blunt Body Flow Field." Thesis, 2007. http://hdl.handle.net/2005/881.

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A body exposed to hypersonic flow is subjected to extremely high wall heating rates, owing to the conversion of the kinetic energy of the oncoming flow into heat through the formation of shock waves and viscous dissipation in the boundary layer and this is one of the main concerns in the design of any hypersonic vehicle. The conventional way of tackling this problem is to use a blunt fore-body, but it also results in an increase in wave drag and puts the penalty of excessive load on the propulsion system. An alternative approach is to alter the flow field using external means without changing the shape of the body; and several such methods are reported in the literature. The superiority of such methods lie in the fact that the effective shape of the body can be altered to meet the requirements of low wave drag, without having to pay the penalty of an increased wall heat transfer rate. Among these techniques, the use of local energy addition in the freestream to alter the flow field is particularly promising due to the flexibility it offers. By the suitable placement of the energy source relative to the body, this method can be effectively used to reduce the wave drag, to generate control forces and to optimise the performance of inlets. Although substantial number of numerical investigations on this topic is reported in the literature, there is no experimental evidence available, especially under hypersonic flow conditions, to support the feasibility of this concept. The purpose of this thesis is to experimentally investigate the effect of energy deposition on the flow-field of a 120� apex angle blunt cone in a hypersonic shock tunnel. Energy deposition is done using an electric arc discharge generated between two electrodes placed in the free stream and various parameters influencing the effectiveness of this technique are studied. The effect of energy deposition on aerodynamic parameters such as the drag force acting on the model and the wall heat flux has been investigated. In addition, the unsteady flow field is visualised using a standard Z-type schlieren flow visualisation setup. The experimental studies have shown a maximum reduction in drag of 50% and a reduction in stagnation point heating rate of 84% with the deposition of 0.3 kW of energy. The investigations also show that the location of energy deposition has a vital role in determining the flow structure; with no noticeable effects being produced in the flow field when the discharge source is located close to the body (0.416 times body diameter). In addition, the type of the test gas used is also found to have a major influence on the effectiveness of energy deposition, suggesting that thermal effects of energy deposition govern the flow field alteration mechanism. The freestream mass flux is also identified as an important parameter. These findings were also confirmed by surface pressure measurements. The experimental evidence also indicates that relaxation of the internal degrees of freedom play a major role in the determination of the flow structure. For the present experimental conditions, it has been observed that the flow field alteration is a result of the interaction of the heated region behind the energy spot with the blunt body shock wave. In addition to the experimental studies, numerical simulations of the flow field with energy deposition are also carried out and the experimentally measured aerodynamic drag with energy deposition is found to match reasonably well with the computed values.

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20

Anderson, Kellie. "Interaction of heated filaments with a blunt body in supersonic flow." 2010. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000052093.

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21

"Aerothermodynamic optimization of Earth entry blunt body heat shields for Lunar and Mars return." UNIVERSITY OF MARYLAND, COLLEGE PARK, 2009. http://pqdtopen.proquest.com/#viewpdf?dispub=3359388.

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22

Leibowitz, Matthew Gregory. "Hypervelocity Shock Tunnel Studies of Blunt Body Aerothermodynamics in Carbon Dioxide for Mars Entry." Thesis, 2020. https://thesis.library.caltech.edu/13726/8/FINAL_Leibowitz_Dissertation_05_27_20.pdf.

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A low mass and reliable thermal protection system for Martian atmospheric entry requires an accurate prediction of the aerothermal environment encountered by the spacecraft. In order to move forward with predictive models for larger vehicles needed for manned and sample return missions, anomalous data needs to be resolved. This work aims to address two critical problems relevant for Mars missions.

I) We investigate significant discrepancies between experimental and simulated blunt body bow shock standoff distance in ground test facilities. Experiments using high-speed and high-resolution schlieren imaging are conducted in the T5 reflected shock tunnel and the Hypervelocity Expansion Tube (HET) to examine facility independence of the measurements. A recently-developed model for sphere and sphere-cone behavior is in good agreement with experiments, and with predictions from Navier-Stokes simulations with thermal and chemical nonequilibrium. The need to account for the divergence of the streamlines in conical nozzles is highlighted. The contributions of vibrational and chemical nonequilibrium to the stagnation-line density profile are quantified using the simulation results in order to compare different reaction rate models.

II) We measure and characterize carbon dioxide mid-wave infrared radiation in hypervelocity flow. Initially assumed negligible in the design of the Mars Science Laboratory (MSL) mission heat shield, this mechanism of heating must be considered for accurate predictions of the heating environment. Specifically, carbon dioxide radiation can be a dominant source of heating in the afterbody, particularly later in the trajectory at lower velocities. Presented are spectral measurements of the 4.3 μm fundamental band of carbon dioxide radiation measured using fiber optics embedded on the surface of an MSL scaled heat shield model. When comparing experiments and simulations, good agreement is found when running the HET in shock tube mode where the shock layer is optically thick, while discrepancies are observed in expansion tube mode where the shock layer is optically thin. A thorough analysis of flow features in the line-of-sight including freestream uncertainties is performed to explore possible reasons for this discrepancy. After developing the spectroscopic calibration technique and obtaining forebody measurements in the expansion tube, an experimental campaign is completed in the T5 Reflected Shock Tunnel to measure spectral radiation in the forebody and afterbody. The accompanying T5 simulations needed for radiation predictions are being carried out by NASA Ames.

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Brooks, Gregory P. "A Karhunen-Loève least-squares technique for optimization of geometry of a blunt body in supersonic flow." 2003. http://etd.nd.edu/ETD-db/theses/available/etd-05062003-110151/.

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Thesis (Ph. D.)--University of Notre Dame, 2003.
Thesis directed by Joseph M. Powers for the Department of Aerospace and Mechanical Engineering. "June 2003." Includes bibliographical references (leaves 148-152).

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Chu, Kuan-Yu, and 朱冠宇. "Analysis of Aero Dynamic-Heating and Drag of Hypersonic Flows over A 3-D Blunt Body at Angle of Attack." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/14771151169314432711.

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Дисертації з теми "Blunt body"

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