Flow Asymmetry and Resonance Characteristics of a Supersonic Rectangular Cavity at Yaw

The sensitivity of rectangular cavity flows to yaw orientation remains largely unexplored, yet understanding this effect is critical to elucidating the asymmetric flows and acoustic resonances that arise in otherwise symmetric configurations. The present experimental investigation is conducted for a shallow, open, three-dimensional rectangular cavity with a length-to-depth-to-width ratio of 4.5:1:1 at Mach 2. The cavity is systematically yawed to assess the influence on the onset and evolution of flow asymmetry and resonance characteristics. The baseline cavity, in line with the freestream flow, exhibits instantaneous flow asymmetry, manifested as competing bistable contrarotating vortical states that switch stochastically at very low frequencies. However, cavity yaw locks a particular rotational state, eliminating low-frequency switching behavior. Cavity yaw significantly affects the resonance characteristics. At zero yaw, the spectra exhibit pronounced intermittency and an anticorrelated redistribution of spectral energy between spanwise-separated cavity locations, whereas cavity yaw produces spatially consistent spectra with no intermittency. For the yawed cavity, the dominant mode shifts from mode 4 to mode 2. The results reveal that even modest yaw angles can substantially alter the nature of the cavity flow dynamics.