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Title: Transonic shock/boundary layer interaction control using three-dimensional devices
Author: Holden, H. A.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2004
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Abstract:
Shock/boundary layer interactions (SBLIs) occur in a wide variety of practical applications, such as: civil aircraft at cruise, helicopter rotor blades in forward sweep and in the intakes to supersonic jet engines. Controlling the shock so as to reduce drag is a subject of considerable interest to aerodynamicists. It has been shown that a wide variety of different types of three-dimensional device give a two-dimensional bifurcated l shock structure which persists in the spanwise direction. Viscous losses tend to be confined to narrow regions downstream of the devices, which means that three-dimensional devices have the potential to give global drag reductions. It was found that the flow control mechanism for each device was the same for an attached SBLI at Mach 1.3 as for a separated SBLI at Mach 1.5. The Slots and Grooves had the greatest flow deflection effect. It was found that a re-expansion previously observed over a Groove control device could be eliminated by increasing the Groove width and altering the internal geometry to slow the upstream flow of air within the device, giving more sustained blowing. The flow deflection effect of the 3D Bumps was reduced by flow ‘spilling’ off the edges of the device. It was found that this effect could be reduced or eliminated by increasing the device width or adding fences to its outer edges. Some of the 3D Bumps were also found to introduce counter-rotating vortices into the flow, which appear to be of a similar strength to those produced by the SBVGs. The SBVGs caused a re-expansion, which had a detrimental effect on the total pressure losses (and hence on drag), however, at Mach 1.5 the Wedge-type SBVGs were found to weaken, and the Vane-type SBVGs to eliminate, a shock-induced separation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.604154  DOI: Not available
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