LAUSR

As wind-power installations increase rapidly worldwide in both number and capacity, the noise problems created by wind turbines, which increasingly are being installed near residential areas, are becoming more pressing. For noise-reduction purposes, a wind turbine can be viewed as being a mechanism for generating aerodynamic noise, and key to that noise reduction is a precisely localized sound source. In this paper, the acoustic signal of an S-wing horizontal-axis wind turbine with a diameter of 1.4 m is acquired using a 60-channel microphone array. Using beamforming, the sound-source distribution and frequency characteristics are analyzed in detail, showing different frequency bands at different wind speeds and tip speed ratios. The results show that the sound pressure level of the sound source (i) decreases gradually with increasing frequency band and (ii) increases gradually with increasing wind speed and tip speed ratio. The radial location of the sound source approaches the blade tip gradually, but the variance is not large. The relevant experimental data and conclusions provide a research basis for exploring the mechanism for the aerodynamic noise and ways to reduce it.