Response of a Ramped Cavity to Shock-Induced Distortions in a Mach 3 Freestream

摘要

The effects of inlet distortions on a ramped cavity in a Mach 3 freestream were experimentally investigated using particle image velocimetry (PIV). A wall-mounted shock generator produced oblique shock waves, consistent with the inlet distortions expected from a vehicle forebody. Mean-flow results from three different shock impingement locations, as well as a baseline undistorted case, show that the location of the impinging shock wave has a profound effect on the height of the cavity shear layer, as well as the position of the primary recirculation. A statistical analysis of the flow directionality indicates that the cavity flowfield is predominantly unsteady when the shock generator is in the furthest upstream position, while the region of unsteady streamwise velocity is reduced when the shock wave impinges on the cavity. The displacement of the shear layer was amplified by the presence of the upstream distortion, exhibiting a broadband behavior over the cavity center. Finally, lower-order approximations of instantaneous images suggested that the mean velocity field is able to capture the salient features of the flow, despite the possible biasing effects of local flow reversal.