Instrumentation Technique for Mixed Hypersonic Flow in Short Duration Facility

At hypersonic Mach numbers, the separated boundary layer from the model base develops as a shear layer and separates the outer in-viscid hypersonic flow from low subsonic flow in the base region. Characterizing such a complex mixed hypersonic flow of the base region in a short duration facility needs adequate runtime since base flow itself takes few milliseconds to establish as well as fast response sensors and instrumentation. In the present study fast response sensors are developed and time taken to establish base flow on a typical blunt body is calculated. These experiments were carried out in a shock tunnel at free stream Mach number of 6 and free stream Reynolds number of 0.2 million. To gain additional confidence on the base heat transfer distribution, steady pressure measurements were also carried out in a conventional hypersonic wind tunnel. The studies indicate that for the above test conditions, the heat transfer and pressure distribution on the blunt body base plane is nearly uniform. The time required for the base flow establishment is 1.27 milli seconds.