Unsteady nature of shock-wave/turbulent boundary-layer interaction

This study addresses the unsteady aspect of shock-wave/turbulent boundary-layer interaction. The interaction was generated using a two-dimensional compression ramp at a freestream Mach number of 2.9. Three models were tested, with flow conditions ranging from fully separated to incipient separation. An array of flushmounted, miniature, high-frequency pressure transducers was used to make multichannel measurements of the fluctuating wall pressure within the interaction. The present results show that, upstream of the mean separation line, the flow is dominated by the large-scale flapping motions of a single sharp shock wave. Instantaneously, this shock front is considerably spanwise nonuniform, giving it a rippling appearance. In the separated region, however, convective turbulence phenomena play a much larger role. The energy containing turbulent eddies above the recirculation zone and traveling in the downstream direction appear to be the major contributors to the wall pressure fluctuations. Here, the time scale of the pressure signals is found to decrease significantly as the shock strength is increased.