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Scramjet testing at high enthalpies in expansion tube facilitiesMatthew McGilvray Unknown Date (has links)
With the high costs of flight testing, especially at hypersonic speeds, ground based facility testing of scramjets becomes an attractive option. The expansion tube is the only facility currently that can offer full flight property duplication at the total pressures and total enthalpies required, while maintaining correct chemical composition. Due to difficulties with short test times and unsteady flow phenomena, scramjet testing in these facilities has not been thoroughly investigated. This study examines these issues, in order to explore the practicality of testing a full ’tip to tail’ scramjet engine at a true flight replication condition in an expansion tube facility. An investigation was initially undertaken on the large X3 expansion tunnel facility to maximise test time and core flow, aimed at producing a 30 km altitude, Mach 10 flow condition. This was identified as the limitation point of the T4 reflected shock tunnel, which has generally been accepted to produce reliable scramjet data for propulsion tests. Using a condition that is also able to be produced in the T4 facility, will permit direct comparison of data between the two facilities in the future, providing confidence in results from expansion tube facilities. Both experimental measurements and numerical calculations showed that the limitation of the test time was due to large boundary layer growth after transition, which engulfed the entire core flow 200 μs into the test time. This phenomenon is likely to affect all scramjet duplication conditions in expansion tubes, as the flow properties are conducive to boundary layer transition occurring. Two solutions where proposed and investigated in order to overcome the flow disruption caused by boundary layer transition; the use of a steady expansion nozzle at the acceleration tube exit; the use of hydrogen as an accelerator gas. Since the smaller X2 facility had a Mach 10 steady expansion nozzle and X3 was decommissioned for the free piston driver to be upgraded, the investigation was shifted to X2. Due to a restricted test time of 550 μs, the static pressure of the flow condition was increased to allow a reduction in the length of the scramjet (pressure-length scaling). A combination of experimental and numerical calculations of the facility was used to define the flow properties. With the confidence of overcoming the phenomenon associated with boundary transition in the X2 facility, numerical modelling of the X3 facility with a steady expansion nozzle was then undertaken to show a 1 ms condition could be produced. Although initially promising, the hydrogen accelerator gas solution requires further investigation. A two dimensional scramjet was designed with upstream injection for testing in X2. This was a three shock inlet with a constant area combustor and a planar thrust surface. Since the flow condition involved changes in flow properties during the test time, aninvestigation of the appropriateness of a quasi steady analysis was undertaken. Using a fuel off simulation of the scramjet duct with the transient inflow properties from the X2 facility nozzle exit, the convective terms for pressure were shown to be two orders of magnitude larger than local terms indicating the dominance of the convective terms change in flow properties at any location allowing quasi-steady flow to be assumed. A normalisation procedure was developed to deal with the transient nature of the data and to accurately represent the axial progression of the gas through the duct. The numerical simulations were also used to show that both flow establishment was achieved and that impulsive starting of the intake would occur. Experimentation with the scramjet using static pressure measurements throughout the body side of the engine provided verification of supersonic combustion. This was verified by the doubling of the static pressure from the start to the end of the combustor for an air test gas, whereas with a nitrogen test gas no significant change in pressure occurred. Effects of fuel equivalence ratio, injector size and cowl position were also investigated. A net inviscid thrust was predicted, using the quasi-steady flow analysis, indicating a specific impulse of 183 s. This work provides evidence to validate the use of expansion tube facilities for experimental testing of scramjets at flight duplication conditions. Limitations due to boundary layer transition flow effects has been shown to be avoidable. Numerical simulations of the facilities showed good agreement with experimental measurements, allowing definition of freestream properties and can now be applied to further scramjet conditions with confidence. Stable, supersonic combustion was shown to be produced for these expansion tube conditions. Coupling the transient simulation of the flow condition with a numerical calculation of the fuel off experimental scramjet has been useful in both verification of the design and performance predictions. Appropriate techniques have been presented to analyse scramjet pressure and thrust measurements where transient effects are present in the freestream.
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Caractérisation des gènes de résistance aux glycopeptides chez les bactéries de la flore intestinale autres que les entérocoques /Domingo, Marc-Christian. January 2007 (has links) (PDF)
Thèse (Ph. D.)--Université Laval, 2007. / Bibliogr.: f. 210-236. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.
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Is knowing half the battle? an examination of the relationship between folic acid knowledge and awareness and daily supplementation with folic acid among 18 to 24 year old women who are not contemplating pregnancy /Kilker, Katie P. January 2007 (has links)
Thesis (M.P.H.)--Georgia State University, 2007. / Title from file title page. Russ Toal, committee chair; Catherine McCarroll, Joseph Mulinare, committee members. Electronic text (83 p. : ill.) : digital, PDF file. Description based on contents viewed Jan 8, 2008. Includes bibliographical references (p. 79-83).
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Diagnostic-intervention et système de mise en marché pour une P.M.E. manufacturière en émergence : le cas Techtube inc /Fortin, Michel. January 1984 (has links)
Mémoire M.A. (Gestion des P.M.O.)-- Université du Québec à Chicoutimi, 1984. / "Mémoire de recherche-action (Cours 2PM0900)" CaQCU Document électronique également accessible en format PDF. CaQCU
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Expression and function of EphA4 and ephrin-As in avian trunk neural crest migrationMcLennan, Rebecca, January 2004 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 179-221). Also available on the Internet.
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Expression and function of EphA4 and ephrin-As in avian trunk neural crest migration /McLennan, Rebecca, January 2004 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 179-221). Also available on the Internet.
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Change in practice used to quantify breast milk intake of pre-term infants in a neonatal intensive care unit test-weighing to "Salt Lake City Feed Plan"/Treloar, Allison Kirsch. January 2009 (has links) (PDF)
Professional paper (M Nursing)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Elizabeth S. Kinion. Includes bibliographical references (leaves 40-43).
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Absorption of pteroylglutamic acid and pteroylpolyglutamic acid in women with a history of neural tube defect affected pregnancies vs. controls /Neuhouser, Marian L. Stone. January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [145]-157).
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Transport boundaries for pneumatic conveyingYi, Jianglin. January 2001 (has links)
Thesis (Ph.D.)--University of Wollongong, 2001. / Typescript. Bibliographical references: leaf 218-232.
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The teratogenic effects of hypervitaminosis A on the formation of the neural tubeGeelen, Johannes Antonius Gerardus, January 1980 (has links)
Thesis (doctoral)--Nijmegen, 1980.
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