Wall pressure fluctuations in the reattachment region of a supersonic free shear layer

Results are presented of a study designed to examine the unsteady shock wave interaction formed in the reattachment zone of a separated supersonic flow in which the separation occurred in the absence of a separation shock. Wall pressure fluctuation measurements were conducted in the Princeton University 203 mm-203 mm high-Reynolds number blowdown supersonic wind tunnel at a freestream Mach number of 2.92 and a unit Re number of 6.7 x 10 to the 7th/m. Reattachment accurred on a 20-deg ramp. It was found that, contrary to previous observations of such flow, the reattachment region was highly unsteady and the pressure fluctuations were significant. The overall behavior of the wall pressure loading was similar in scale and magnitude to the unsteadiness of the wall pressure field in compression ramp flows at the same Mach number.