Noise generated by flow over perforated surfaces

Nelson, P. A. (1982) Noise generated by flow over perforated surfaces. Journal of Sound and Vibration, 83 (1), 11-26. (doi:10.1016/S0022-460X(82)80072-2).

Record type: Article

Abstract

This work deals with the prediction of the noise generated by unsteady flow over the surface of acoustically absorbent duct linings. Ffowcs William's analysis of the acoustics of turbulence near sound absorbent linings is used as a theoretical basis. An equivalent source model is used to describe the radiated sound in terms of the mass flow driven through the circular perforations of a liner surface by hydrodynamic pressure fluctuations. The assumption of a realistic form for the turbulent velocity fluctuations in the liner perforations makes clear the inherent dependence of the radiated noise on the Strouhal number based on hole diameter. The predictions of the equivalent source model are in excellent agreement with measurements made of the noise radiated by liner surfaces in a free jet test rig. The model and the experimental data are further used to predict successfully the level of surface generated noise in attenuator sections of low speed flow ducts.

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Published date: 8 July 1982

Additional Information: Funding Information: The author gratefully acknowledges Sound Attenuators Limited for their financial support and for permission to publish this work. The author also wishes to thank Professor P. E. Doak and Dr C. L. Morfey for many helpful discussions during the course of this research. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.