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Conference Papers Journal of the Acoustical Society of America Year : 2016

A numerical study of inflow turbulence distortion in the vicinity of blade leading edges

Gwenael Gabard
Vincent Clair

Abstract

The interaction of the rotor with inflow turbulence is a source of broadband noise, dominant at high wind speeds. In the vicinity of the leading edge of realistic blades, the mean flow distorts the turbulence, resulting in an attenuation of the high-frequency part of the radiated noise compared to zero-thickness blades. In this paper, to study this turbulence distortion by the mean flow, two different numerical approaches are considered. First, the linearized Euler equations are solved in the time-domain using a finite difference code to model the response of an isolated blade interacting with synthetic turbulence. Second, a vorticity approach is applied, using the Biot-Savart law combined with a vortex panel method. Using these approaches on multiple configurations, the up-wash velocity fluctuations along a streamline which goes to the stagnation point, show a decrease of the turbulent levels, from a threshold distance independent of the wavenumber. This decay is then inverted for low frequencies after a wavenumber dependent threshold distance. The turbulence characteristics are found to have no effect on the distortion, whereas the geometry forward the position of the maximum thickness has an effect on this distortion. The full paper will contain more physical insights responsible for this distortion.
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Dates and versions

hal-03157649 , version 1 (03-03-2021)

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Thomas Hainaut, Gwenael Gabard, Vincent Clair. A numerical study of inflow turbulence distortion in the vicinity of blade leading edges. 172nd Meeting of the Acoustical Society of America, Nov 2016, Honolulu, Hawaii, United States. ⟨10.1121/1.4970824⟩. ⟨hal-03157649⟩

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