Aeroacoustics of Low Mach Number Flows

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Trailing edge and roughness noise

Abstract

Airfoils and other fluid dynamic devices generate noise as a result of turbulence and unsteadiness in the boundary layers and other viscous flow regions that grow from their surfaces. This is called self-noise. In this chapter we focus our discussion on self-noise generated by turbulent boundary layer over a sharp trailing edge and the flow of the boundary layer over a rough wall. The fundamental origins of these noise sources are discussed. We present both Amiet's prediction method for trailing edge noise and the empirical approach of Brooks, Pope, and Marcolini. The scattering theory of roughness noise is explained, and the possibility of using designed-rough surfaces to radiate specific portions ...