Prediction Of The Noise For The Wind Turbine Rotating Blade Based On FW-H Equation

The aerodynamic noise of the rotating blades makes up the main source of the wind turbine noise,and how to reduce the noise of rotating blades is of great significance for wind turbine design. Basedon the time domain solution of the FW-H acoustic wave equation, the mathematical model of theaerodynamic noise of rotating blades is studied. Combined with Delay Time Method, and under thecondition that the load is steady, the formula of the blade thickness noise and the load noise arederived and simplified, and then the numerical calculation of the rotating blade noise is also given. Inorder to verify the the accuracy of the noise prediction model, the numerical simulation of the rotationnoise of the isolated tail rotor of a helicopter is given, and the comparison between the numericalresult and the experimental data shows a good coincidence. Based upon the numerical simulation of asimple wind turbine blade noise, the characteristics of the distribution of the thickness noise, the loadnoise and the rotation noise within the time domain, the frequency domain and the direction domainare analyzed. As the results of the investigation, some facts are discovered, i.e.: the rotation noise ismainly determined by the load noise, while the thickness noise accounts for a very small proportion ofthe total noise. The rotation noise shows an increasing relationship with respect to the blade span andthe speed and presents a decreasing relationship with the viewing distance. The peak of the noisespectrum is situated at the passing frequency of the blade and its harmonics. All the minima of thethickness noise, the load noise and the rotation noise are located on the rotation axis, and while themaximum thickness noise is on the plane of the rotation, and the maximum load noise and the rotationnoise is on the cone with an apex angle of75degrees.