The three-dimensional characteristics of the unsteady wall-pressure in a low-Mach-number rectangular cavity flow with Rossiter model oscillation

This study is focused on examining the three-dimensional characteristics of the unsteady wall-pressure in a low-Mach-number rectangular cavity with Rossiter model oscillation. The effect of cavity width on the resonance is investigated as well. It is observed that not only the resonance magnitude but also the resonance frequency could be altered when the cavity width changes. As the cavity becomes narrow to W/L ≈1, the resonance frequency decreases substantially comparing to that for W/L >1. While for the narrowest cavity with W/L <1, the resonance frequency is the same as that for the wide cavity. Low-frequency disturbances grow stronger as approaching to the side walls. Instantaneous velocity magnitude measurement simultaneously with the unsteady wall-pressure shows the propagation of flow disturbances highly correlated with the pressure resonance. It is observed that for the cavity with W/L ≈1, the pressure resonance is highly correlated with a local propagation of disturbances near the cavity aft wall. The downstream convecting disturbances in the shear layer are found to be weaken in the cases of W/L ≈1. Meanwhile the convection velocity of shear-layer disturbances is decreased, which results in a decrease of the resonance frequency.