Investigation of fluid-structure interactions coupled with shock-boundary layer interactions over an externally forced elastic panel

Fluid-structure interactions induced by impinging oblique shock-boundary layer interactions on a thin elastic panel are studied in a Mach 2.5 flow. The panel is externally forced using piezoelectric transducers at several structural resonant and non-resonant frequencies. Flow visualization and pressure sensitive paint (PSP) in conjunction with piezoelectric transducers provide simultaneous measurements of flow and structural response. Spectral Proper Orthogonal Decomposition of PSP data reveals greater two-dimensionality in the intermittent region for unforced cases only at structural resonant frequencies, while forced cases show this even at non-resonant frequencies. Bispectral analysis indicates stronger coupling between frequencies below structural resonances in forced cases compared to unforced. Flow visualization shows that forcing at non-resonant frequencies reduces separation length by up to 25%, versus 10% at resonances. Forcing at resonant frequencies also yields a more two-dimensional separation line. Piezoelectric forcing offers a lightweight, low-power method to reduce flow separation in shock-boundary layer interactions.