Experimental Investigation on the Flow-Induced Oscillation in Deep Cavity and the Controlling Effect Using Wedge Spoiler

Flow-induced oscillation is an important phenomenon in cavity flow. It will produce strong aeroacoustic noise and radiate to the far-filed with limited attenuation. Through various approaches, the flow-induced oscillation in deep cavity and its controlling effect by using wedge spoiler will be experimentally investigated in low-speed aeroacoustic wind tunnel. Proper orthogonal decomposition (POD) method is introduced to extract the time-averaged flow field and discrete vortex mode in cavity flow. Flow-induced mode is acquired and two unknown parameters in Rossiter equation are solved, which is validated in the aeroacoustic experiment. The behavior of flow oscillation in shear layer is detected through hotwire test. Wedge spoilers with different heights and horizontal angles are installed on the leading edge of cavity to evaluate the noise reduction effect, by the means of lifting up the shear layer and suppressing its impingement on rear wall. Higher wedge spoiler could convert the flow pattern from cavity flow to backward-facing step flow. That is benefit to the near-field noise reduction but unfavorable for far-field noise reduction.