Experimental Study of Shock Impingement Over a Compliant Panel With a Turbulent Boundary Layer in Mach 4 Flow

A shock wave-turbulent boundary layer interaction (STBLI) over a compliant panel is experimentally investigated in a Mach 4 Ludwieg Tube to examine the effect of shock impingement location and cavity pressure on the fluid and structure response. Simultaneous structure and flow measurements are obtained using a combined single-camera photogrammetry and colinear focused laser differential interferometry (FLDI) and high-speed schlieren system. Although the impingement location and cavity pressure affected the mean panel deformation shape, the distribution of energy between the panel vibration modes was not significantly affected. A transfer of energy from the low-frequency separation shock foot motion to the panel oscillations was detected in the mid-chord impingement case but not for the leading-edge impingement cases. When the cavity pressure matched the average STBLI pressure load over the panel surface, the separation shock generally led the reattachment shock oscillations at the dominant panel vibration frequency with a weak to moderate level of phase locking. Mid-frequency spectral content in the separation bubble was attenuated by a factor of one third in the mid-chord impingement case compared to the rigid and leading-edge impingement cases.