Effect of Cavity Pressure on the Response of a Compliant Panel at Mach 2

An experimental investigation was performed to study the effect of pressure gradient on fluid–structure interactions over a fully clamped compliant panel subject to shock wave boundary layer interactions (SBLIs). These experiments aimed to understand the time-averaged and unsteady aspects of fluid–structure interactions at Mach 2. A pressurized cavity underneath the compliant panel created the pressure gradient across the surface. A wedge-shaped shock generator was used to impinge the shock on the centerline of the panel. The interactions on a rigid flat plate instead of a compliant panel served as the baseline SBLI. Measurements include shadowgraph and surface oil flow visualizations, panel deflections using a laser-scanning vibrometer, and unsteady pressure sensor measurements. Results indicate that the SBLI on the compliant panel is three-dimensional as compared to the rigid plate with nominally two-dimensional interactions. The curvature of the separation line and the separation bubble length were observed to be strong functions of the pressure gradient across the panel. The panel dynamics in the case of shock impingement were observed to be multimodal. A shift in the panel vibration modes was observed with a change in pressure gradient. Also, the shock unsteadiness (streamwise excursion length of the shock) levels are larger for a compliant panel than for a rigid plate. These results indicate that aeroelastic coupling resulting from pressure gradient across the panel significantly modifies the surface flow features and structural properties of the panel.