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 .
© 2012 Springer-Verlag Berlin Heidelberg. The authors thank Prof. Hans G. Hornung for invaluable guidance, advice, and other contributions on both the conception and execution of this work, and Mr. Bahram Valiferdowsi for his work with design, fabrication, and maintenance. This project was sponsored by the Air Force Office of Scientific Research under award number FA9550-10-1-0491, for which Dr. John Schmisseur is the program manager. The views expressed herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of AFOSR or the U.S. Government.