DynaWEA - From the dynamics to the acoustics of a gearless wind turbine
The aim of the joint venture DynaWEA is the analysis of the structure-borne sound radiation of a wind turbine with a high-pole ring generator (externally-fed direct-drive rotor).The structure-borne sound excitations originating from the generator of these wind turbines have a significant influence on the overall noise emission of the wind turbine, which is caused by the operating vibrations of the generator, which are transmitted to the rotor blades, the tower and the cladding via load-bearing structural components, and from there as airborne noise. Due to the periodic course of the exciting forces, tonal sound excitations occur. If the overall system is poorly designed in terms of the interaction of excitation, structure-borne sound transmission and sound emission, corresponding tonal noises can occur in the vicinity of the turbine. Larger wind turbine performance classes and acoustic improvements in broadband aero acoustic noises increase the perception of tonal sound emissions.
For the study, electromagnetic models of the machine are implemented with a multi-body simulation of the system structure dynamics, considering air gap imperfections and thermal effects, and are validated by measurements at the system test bench of the CWD.
Another work package of this research project is the development and adaptation of cooling concepts enabling the optimization of the air gap geometry. The focus of the generator air gap optimization is on improving the drive train dynamics and reducing the noise emissions of the wind turbine.