Effect of Gas Injection on Transition in Hypervelocity Boundary Layers
A novel method to delay transition in hypervelocity flows in air over slender bodies by injecting CO2 into the boundary layer is presented. The dominant transition mechanism in hypersonic flow is the inviscid second (Mack) mode, which is associated with acoustic disturbanceswhich are trapped and amplified inside the boundary layer . In dissociated CO2-rich flows, nonequilibrium molecular vibration damps the acoustic instability, and for the high-temperature, high-pressure conditions associated with hypervelocity flows, the effect is most pronounced in the frequency bands amplified by the second mode .
KeywordsSound Absorption Boundary Layer Transition Stanton Number Shock Tunnel Transition Delay
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