The partially ensonified zone of wind turbine noise

• Model of noise generation and propagation from three blade wind turbine.
• A turbine blade as a line source with increasing sound power from the hub.
• Wind shear refraction yields fully ensonified zone, partially ensonified zone, and shadow zone.

Complaints concerning wind turbine noise have been more widespread in recent years. This is a modeling paper on noise generated by a three blade wind turbine. A single blade is treated as a linear source with the sound power growing from the hub to the tip. The main contribution of this study is the idea of the partially ensonified zone (PEZ), which separates the fully ensonified zone (close to the turbine) and the shadow zone (far away from the turbine). PEZ comes from a blade – a linear source and the wind shear refraction. The commonly used methods provide the A-weighted time average, LAeqT, inside the fully ensonified zone. The main finding is the method of LAeqT estimation within PEZ.