Wind turbine noise prediction using Olive Tree Lab Terrain

Calculation of noise propagation from wind turbines is complex, and large variations of sound immission levels are commonly observed at the same wind speed. These variations are influenced by sound emission (aerodynamic noise), but also by meteorological parameters such as temperature gradient, wind speed profile, wind direction, and turbulences. Commonly used models (ISO 9613-2 and Nord2000 for example) generally predict the average sound pressure levels adequately under downwind conditions, but often fail to predict noise levels in upwind conditions. In this paper we present the results of a collaborative research between SIXENSE Environment (ex SOLDATA Acoustic) and P.E Mediterranean Acoustics Research & Development (PEMARD), using on site experience on more than 350 French windfarms, and Olive Tree Lab Suite v4.0 software which uses wave based geometrical acoustics to calculate sound propagation, including atmospheric refraction. The goal is to combine both approaches and introduce and test key parameters for wind turbine noise prediction. Calculation results are compared to long term noise & meteorological measurements. A good correlation is shown between calculation and measurements even in case of complex meteorological situations.

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