Numerical Approach for Noise Reduction of Wind Turbine Blade Tip with Earth Simulator

The purpose of this research is to investigate the physical mechanisms associated with tip vortex noise caused by rotating wind turbines with giant size of computational fluid dynamics. The flow and acoustic field around the WINDMELIII wind turbine is simulated using compressible Large-Eddy simulation (LES), with emphasis on the blade tip region. The acoustic near field is simulated directly by LES whereas the far field is modeled using acoustic analogy. Due to the fine grid employed, smallest eddy scales near the blade surface are resolved. Aerodynamic performance and acoustic emissions are predicted for the actual tip shape and an ogee type tip shape. A decrease of the sound pressure level in the high frequency domain is observed for the ogee type tip shape. The present simulation research using the Earth Simulator shows that large scale simulation is really useful in designing the aerodynamic manufacturing such as the wind turbine.

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