Shear sheltering is defined as the effect of the mean flow velocity profile in a boundary layer on the turbulence caused by an imposed gust. It has been studied extensively in applications involving boundary layer transition, where the primary concern is flow instabilities that are enhanced by turbulence in the flow outside the boundary layer. In aeroacoustic applications turbulent boundary layers interacting with blade trailing edges or roughness elements are an important source of sound, and the effect of shear sheltering on these noise sources has not been studied in detail. Since the surface pressure spectrum below the boundary layer is the primary driver of trailing edge and roughness noise, we will consider the effect that shear sheltering has on the surface pressure spectrum below a boundary layer. We will model the incoming turbulence as vortex sheets at specified heights above the surface and show, using classical boundary layer profiles and approximations to numerical results, how the mean flow velocity can be manipulated to alter the surface pressure spectrum and hence the radiated trailing edge noise.
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