Modelling of ground and atmospheric effects on wind turbine noise

International audienceAmiet's analytical model for trailing edge noise is used to predict the noise radiated by a Siemens SWT 2.3-93 wind turbine. Good agreement with experiment is found for sound power level (SWL) spectrum for frequencies higher than 1kHz. The immission level is then calculated with an image source model and compared with point source calculation. Ground reflection and atmospheric absorption are considered for the propagation model. The effect of ground reflection is seen to modify the sound pressure level spectrum and the amplitude modulation strength. The point source approximation yields accurate results for the overall sound pressure level, but exaggerates interference dips in the spectrum and thus overestimates the strength of amplitude modulation