Turbulent Inflow Noise Prediction from Wind Turbine Blades

Abstract

In general, wind turbine blades operate in subsonic regions along with turbulent flow conditions. This paper deals with noise due to turbulent inflow around the blades based on Amiet's and Lowson's model formulation .This mechanism is predicted using numerical simulation for different observer azimuth positions and various rotor speeds of turbine. The influence of turbulence intensity, length scales on the sound pressure levels is illustrated. The effect of blade geometry characteristics on sound pressure levels is implemented. The influence on power production from wind turbine due to the reduction in sound power levels are correlated with the modified blade geometry. The total noise from turbulent boundary layer trailing edge and turbulent inflow mechanisms are compared for three turbines of sizes, 350kW, 2MW & 3MW. Overall sound pressure levels are dominated by the inflow turbulence mechanism. The amplitude modulation is calculated using the sound pressure levels obtained and illustrated for predominantly low and medium range frequencies in octave spectra.