Prediction of Vortex Induced Aerodynamic Noise from Wind Turbine Blades

Abstract

An important aerodynamic noise source from lifting surface occurs from trailing edge of an aerofoil as found in wind turbine blades. In this work, semi-empirical method proposed by Brookes, Pope, Marcolini is applied to evaluate trailing edge bluntness vortex shedding noise source. For low Mach number flows (0.1884) and moderate to high chord Reynolds number, 4.73 × 10 – 3.35 × 10, change in sound power level was assessed for trailing edge thicknesses in terms of 0.1%, 0.5% and 1% chord lengths at wind speeds of 8 m/s, 10 m/s. For overall change of trailing edge thickness from 0.1% to 1% chord, an increase in noise levels up to 50 dB was found at low frequencies, while a decrease up to 30 dB was found between mid-band to high frequencies of spectra.