UNSTEADINESS OF NORMAL SHOCK WAVE/BOUNDARY LAYER INTERACTION IN A SUPERSONIC DIFFUSER

In order to characterize the unsteadiness of normal shock wave/turbulent boundary layer interaction, the detailed experimental explorations were carried out in the supersonic diffusers with the half angle of divergence of 5 to 9 deg. Measurements included the time-mean and fluctuating wall pressures, the shock displacements, the surface oil-tracers, and the pitot pressures in the boundary layer. The optical observation of the interacting flow fields was made by using a spark schlieren method. The Mach number immediately up-stream of the interacting shock wave was in a range of 1.10 to 1.50. The results obtained show that the instantaneous displacements of the shock wave are consisted of large-amplitude, low-frequency and well correlated with the fluctuating wall pressures in the intermittent region of shock wave/boundary layer inter-action.