The Analysis Of The Wake Filed Aerodynamic Noise Of Wind Turbine Based On LES/FW-H

Environmental pollution is caused by the Aerodynamic noise, in some cases, but also results in fatigue and damage of the structural. With the small-scale wind turbine closer to mankind’s production and life, which pays attention to solving of the noise problem. With the research of the computational fluid dynamics (CFD) and computational aero acoustics (CAA), using numerical methods to investigate wind turbine aero acoustics is necessary and inevitable. This article was calculated wind turbine wake flow field, for the leaf surface and the wake flow field turbulence characteristics of the particular region with the LES / FW-H of the fluent software, combining with the aerodynamic parameters of flow field for the calculation of FW-H and FFT transformation, and describing the mechanism that the flow field between noise correlation and analyzing the noise related to the distribution of the monitoring points.The results show that the larger pressure fluctuations are had the tip part of surface rotating wind wheel. the wake flow fields of unsteady are mainly concentrated in the tip section area, trailing edge region and central region.The attenuation characteristics of the tip flow field noise is analysied, Rotation Noise is the one of keying noise on the frequency band, trailing edge region noise is one of high-frequency of the wind turbine aerodynamic noise. Sound pressure level of Wake center region increase the increasing of the tip speed ratio. The sound pressure level decrease as the increasing of the distance from the wheel center at the axis direction, but increasing at 15 direction.The radiation noise gradually reduce with the monitoring round of the tip to rotate the wind outside the movement near the end of the tip flow field along the radial direction; the sound pressure level of different monitoring points increase as the increasing of the tip speed ratio,which the rate of increasing become smaller with increasing distance from the rotation plane, and even tended to be stable. According to Analysis of directional draw, noise does not change in the rotating plane; the noise is smaller along the axial direction ;the noise has a larger directivity along the tip vortex diffusion direction; and noise shows a greater amplitude.According to the contrasting with the test and calculation results ,the calculation results show that the method is predicted wind turbine aerodynamic noise, and providing the theoretical basis for the experimental test, which in order to further optimize the wind turbine blades to lay a good foundation. Comparison of three special directions of the noise, the axial direction is smaller, from the rotation axis to rotate plane gradually increased, reaching the maximum. The the noise of the direction on the rotating plane does not change. But in the tip end of flow direction show a larger directional.