Turbulence and Upstream Shock Wave-Boundary Layer Interaction Effects on Compliant Structures

This study examines the effects of upstream shock wave-boundary layer interaction on fluid-structure interaction and the interaction between turbulence and structural responses. The configuration examined is a panel located downstream of a 24° compression ramp. First, the ramp is exposed to Mach 4 flow, and the frequency content of pressure fluctuations in the turbulent boundary layer upstream and downstream of the compression corner is compared. It is found that intermediate frequencies that may influence fluid-structure interaction propagate into the downstream boundary layer. Next, the coupling mechanism between turbulence and structural responses is studied. Changes in turbulence caused by structural deformations are examined, followed by an investigation into the aeroelastic effects of modified turbulence on a flexible panel. One-way coupling exists between turbulence and structural responses because structural deformations significantly affect turbulence properties, but variations in turbulence have minor effects on structural responses. Finally, the role of turbulence in fluid-structure interaction is determined. Pressure fluctuation histories of varying intensity are applied to panels of varying thickness. A threshold is established indicating when boundary layer turbulence causes moderate structural deformations. The findings of the paper provide guidelines for designing control surfaces of hypersonic vehicles subjected to turbulent shock wave-boundary layer interaction effects.