Low frequency noise from MW wind turbines: Mechanisms of generation and its modeling

Abstract

During the present project the mechanisms of generation of low frequency noise (LFN) for upwind rotors has been investigated. A 3.6 MW turbine has been simulated with a noise prediction model from NASA in US. Running the model on this turbine a number of important turbine design parameters with influence on the LFN have been identified as well as other parameters not linked to the turbine design. Of important parameters can be mentioned • rotor rotational speed • blade/tower clearance • • rotor configuration - upwind/downwind unsteadiness/turbulence in inflow Further, the directivity characteristics of LFN has been computed as well as reduction in noise as function of distance from the turbine. In general low levels of LFN has been computed for the upwind rotor in standard configuration