To investigate yaw's influence on aerodynamic noise
the NREL 5MW was studied using a semi-empirical model to analyze sound field directionality
sound radiation spectrum
sound propagation
and amplitude modulation noise in the near wake region under zero yaw and counterclockwise rotations of 5°
10°
and 20°around the + axis. Results show that yaw rotates the sound source direction
with sound pressure level and spectral characteristics largely unchanged. Peak sound pressure level is in the mid-to-low frequency range; axial and radial noise attenuates with yaw
but axial noise increases. Amplitude modulation noise is strongest in the crosswind direction
opposite the sound source
and yaw can reduce cross wind amplitude modulation noise by 2-6 dB. Therefore
the sound level and amplitude modulation noise intensity under specific wind directions can be reduced by adjusting the yaw angle.
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