Abstract: Cavity noise caused by the high speed airflow has been paid much attention to in the field of aerospace, as it not only affects normal operation of equipment inside the cavity, but also threatens the structural strength and safety of aircraft. Therefore, the study of cavity noise suppression has important significance in improving the safety of aircraft. Effects of leading edge plate on the flow and noise of the cavity model (the ratio of length to depth is 6) at the flow velocity of Ma=0.9 and of Ma=1.5 are investigated with high speed wind tunnel experiment. Sound Pressure Level (SPL) distribution and spectral characteristics of sound pressure of the noises in the cavity with leading edge plates of different parameters are compared to define the selection method and optimal parameters of the plate. The acoustic and flow field information in the cavity are obtained with the dynamic/static pressure measurement and oil flow experiment. The oil flow patterns of the surfaces and pulsating/static pressure inside the cavity are discussed, and the effect of the leading edge plate on the static pressure, flow structure, sound pressure level and sound pressure spectrum are analyzed. The results show that the leading edge plate can greatly lift the shear layer, raise the impact position on the back wall area, and reduce the flux rate and intensity in the cavity. By controlling the leading edge plate, the static pressure and backflow area are effectively suppressed and the SPL and peak noise also fall down significantly, with the SPL at the aft edge decreasing by 11.13 dB at Ma=0.9 and by 8.0 dB at Ma=1.5. The leading edge plate provides a new method for cavity noise suppression in high-speed flow condition, which can be effectively applied to flow/noise controlling of cavity structure on aircraft, and has important engineering application value and prospect.

Key words: cavity, leading edge plate, high speed flow, noise, flow controlling