Experimental Development of an Aeroacoustic Cavity Noise Controlling Device Utilizing Receptivity of the Flow

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The aim of this research was to develop a device that can suppress the aerodynamic noise generated at cavities. The basic idea was to utilize the receptivity and perform an active control for efficient control of the flow. The research results have shown that aerodynamic noise could be reduced by adjusting the spanwise phase of the periodic fluctuation introduced in to the flow by piezo-blade array attached to the upstream edge of the cavity.However, in the process, it was found that aerodynamic noise could be suppressed by merely placing a small rod-like object to cavity parallel to the upstream wall of the cavity. The effect was confirmed in an application-size environment experiment carried out in a large-scale wind tunnel of Maihara Wind Tunnel Center, Railway Technical Research Institute. The location and size of the object which were most effective for the noise reduction was discovered, however, the mechanism has not been fully understood, yet.