| With the rapid development of wind power generation,wind turbines are developing towards large scale.With the development characteristics of increasing installed capacity,longer blades and larger tip speed ratio,wind turbines and wind farms are getting closer to residential areas.and the noise problem is becoming more and more prominent.Wind turbine noise includes mechanical noise and pneumatic noise.The mechanical noise of wind turbines can be greatly reduced by advanced manufacturing technology,and the aerodynamic noise becomes the main source of noise.In recent years,the methods of studying aerodynamic noise mainly include CFD based numerical simulation and semi-empirical formula based model prediction.However,the numerical simulation based on CFD method generally requires a lot of computational resources and time,and is suitable for the demonstration stage after the preliminary design.This method is rarely used in practical engineering applications.Semi-empirical formula has the advantages of fast calculation speed and high relative accuracy,and is widely used in wind turbine noise prediction.Therefore,the establishment of wind turbine aerodynamic noise prediction model to achieve rapid and accurate prediction of wind turbine noise can help the study of noise reduction measures,including wind turbine location layout,residential area location and animal migration route adjustment.The main work of this paper is as follows:(1)Analyze the progress of wind turbine noise research at home and abroad,as well as the comprehensive influence that the noise may bring.(2)This paper introduces the basic structure of the wind turbine,the relevant aerodynamic theory and the complicated operating conditions in the actual operation(3)The paper studies the basic theory of wind turbine noise,the mechanical noise and aerodynamic noise of wind turbine,discusses in detail the five kinds of noise sources in the aerodynamic noise and explains the relevant generation mechanism(4)Two semi-empirical formulas,BPM and wall pressure spectrum(WPS),were used to model the airfoil self-noise prediction model,and the experimental data were combined to verify the model.(5)For the first time,the blade element momentum theory and the WPS airfoil noise prediction model were adopted,combined with the turbulent inflow noise prediction model,and the MATLAB software was used to establish the wind turbine aerodynamic noise prediction model,including the wind shear effect,tower shadow effect and other unsteady effects of the airflow.(6)The prediction results of the new model are compared with the prediction results of wind turbine aerodynamic noise based on BPM and the actual measured noise data of two given wind turbines.The results show that the prediction results of the new model are in good agreement with the BPM prediction results and the experimental measurement results,which proves that the wind turbine noise prediction model proposed in this paper is effective and feasible,and provides a fast and effective method for the prediction of wind turbine aerodynamic noise.(7)The influence of the pitch Angle,wind speed,turbulence intensity and wind shear coefficient on the aerodynamic noise of the wind turbine is studied.The results show that the aerodynamic noise of the wind turbine can be effectively reduced by increasing the pitch Angle appropriately.The noise of wind turbine is positive to Mach number.Turbulence intensity and wind shear coefficient have great influence on low and medium frequency noise,but have little influence on high frequency noise.(8)The acoustic directivity of the wind turbine is studied.The results show that the noise radiation characteristics of the wind turbine are presented as a dipole sound source,and there is asymmetry due to the distortion of the blades.Therefore,the upwind and downwind locations are usually the areas with the highest noise radiation intensity of the wind turbine.The location of residential areas is generally chosen as the tangent direction of the wind turbine plane. |
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