Aero acoustics of a flow pipe having a single small cavity
Abstract
The whistling of a pipe-cavity system subjected to an internal flow of fluid is considered in this paper. This phenomenon consists in a self-sustained oscillation in the shear layer that develops at the interface between the fluid flow in the pipe and fluid in the cavity. Some basic geometrical relations regarding the sound emission are considered : the cavity length, and the distance between the air inlet and the cavity. The tested pipes had lengths between 0.65m and 1.459m, and all the diameter 42mm. The maximum velocity was 30m/s. A noise reduction experiment is also presented that involves a time harmonic sound superposed on the whistling noise.
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