Non-linear Panel Response to Turbulent Loads in Compound Shock-Wave/Boundary Layer Interactions*

Fluid-structure interactions (FSI), induced by shock-wave/boundary layer interactions (SBLI), significantly influence the design and performance of high-speed vehicles. This study investigates the response of compliant panels to 3D swept SBLI, focusing on double-fin (or crossing-shock) SBLI using one-way fluid-to-structure interactions. Time-resolved pressure-sensitive paint (PSP) measurements for the SBLI with a rigid surface, are employed for turbulent pressure loading on the panel area. The study explores dynamically non-linear panel responses, induced by high cavity pressure differentials. Concurrently, the panel response is evaluated at different non-dimensional dynamic pressures (λ). The low-frequency dynamics of compound SBLI exhibits complex motions moving in both streamwise and spanwise directions, imposing relatively complicated pressure fluctuation loads that are not aligned with any of the principal directions. Beyond a critical λ threshold, the panel response features multiple limit cycles, with intermittent switching between large and small amplitude oscillations. These nonlinearities facilitate energy exchange among different panel modes, which is elucidated using bispectrum analysis. This study highlights the utility of PSP data in parametric FSI analyses.