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Title: Scramjet Intakes: Designing for Performance and Operability.
Author: Munro, Stuart
ISNI:       0000 0001 3432 1337
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2007
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The classical approach to scramjet intake design, analysis, experimental testing, and performance assessment treats the intake as separate from the rest of the vehicle. This thesis argues that a more integrated approach is necessary. The design space of Mach 7 two-dimensional, axi-symmetric spike and Busemann-type intakes with focused forebody waves and throats expanded to the Kantrowitz limit is parameterised geometrically and stream thrust average performance parameters calculated across the range of possible intake designs. An engine cycle is applied to arbitrate between conflicting capability and efficiency design points. The two-dimensional analysis is extended to include angle of attack, off-design Mach number and defocused conditions. Intakes with sharp leading edges and moderate turning angles are found to perform optimally, and the relatively large combustor hydraulic diameter and higher capability of inward turning designs are found to improve engine performance significantly. An upper bound is established for the performance of stream-traced Busemann intakes and it is shown how the performance of truncated Busemann derivatives may be improved by extending the leading edge at constant angle. The thesis also describes complementary experiments investigating intake operability carried out in the University of Oxford's gun tunnel. This facility was converted to operate as a Ludwieg tube with Light piston Isentropic Compression Heating (LICH) to improve flow steadiness when matching Reynolds numbers and temperature ratios to 2:5 scale Mach 7, 30 km altitude flight. Tunnel stagnation temperatures are measured and correlations to the fill pressures and stagnation pressure history are determined. The design and build of a two-dimensional wedge intake with isolator to determine intake starting limits by varying cowl position and shoulder angle is described. The isolator is shown to degrade starting characteristics by increasing the likelihood of internal choking. The implementation of a self-starting test, employing gas injection via fast acting valves, is implemented to demonstrate the self-starting characteristics of an axi-symmetric spike intake with internal contraction exceeding the Kantrowitz limit. Fuel injection and combustor back pressure are also simulated at angle of attack. Boundary layer trips are shown to significantly improve the operability of both models tested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available