Forecasting Method of Shock-Standoff Distance for Forward-Facing Cavity

Experiments are performed on a cylinder with a forward-facing cavity at the tip in the flow of \( M_{\infty } = 10 \) in FD-14A shock tunnel. The shock shape, shock-standoff distance, and oscillation characteristics are captured by the high-speed movie, and the dynamic pressure response is used to correlate with the acoustic characteristics of the cavity base through the transducer. By analyzing the amount of experimental and numerical results abroad, a forecasting method for shock-standoff distance is proposed. Combination of organ-pipe theory with experimental results of oscillation frequency validates the applicability and effectiveness of the method. Results of shock-standoff distance and oscillation frequency are also obtained for experiments in FD-14A shock tunnel. The forecasting results of oscillation frequency are in accordance with the experimental results. Furthermore, the oscillation amplitude and average velocity of the shock wave are analyzed for forward-facing nose cavity at \( M_{\infty } = 10 \).