A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from temperature and airflow. At a given receiver point, the sound pressure is corrected by taking into account these propagation effects. As an overall assumption, the noise field generated by the wind turbine is simplified as a point source placed at the hub height of the wind turbine. This assumtion is reasonable, for the receiver is located in the far field, at distances from the wind turbine that are much longer than the diameter of the rotor.
Wind Engineering, 2005, Vol 29, Issue 2, p. 129-143