The fluid-structure interactions (FSI) generated by impinging shock boundary-layer interactions (SBLI) over a flexible panel are studied to capture the panel vibration effects on the flow field and vice versa. A 1-mm-thick steel panel was employed to generate the FSI and the flow conditions ensured that the panel oscillation amplitude was much smaller than the boundary-layer thickness and plate thickness. An impinging oblique shock was generated by an $8^{\circ }$ shock generator placed incident on a Mach-2.5 flow. Two-dimensional pressure fields over the panel surface and wall-normal deflection at discrete panel locations were simultaneously measured at 10 kHz. Proper orthogonal decomposition and spectral proper orthogonal decomposition (SPOD) methods were employed on the measured pressure fields to analyze the dynamics of the SBLI unit and its feedback coupling with the panel oscillations. Analysis of the eigenspectrum revealed elevations in the vicinity of the panel elastic modes. Visualization of the dominant SPOD modes at the panel elastic frequencies revealed an increased spanwise correlation in the intermittent region that extended almost across the entire panel span. The time evolution of the first SPOD mode at panel elastic modes revealed a streamwise propagating modal peak; by contrast, a predominantly spanwise motion was observed at other frequencies. These observations evidence the promotion of two-dimensionality in the SBLI unit at the panel elastic modes due to the fluid-structure interactions.

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• Flow-structure interactions
• High-speed flow
• Shock waves