Research On Aerodynamic Noise Characteristics And Noise Reduction Method Of Wind Turbine

The aerodynamic noise of wind turbines has a negative effect on the surrounding ecological environment including bird migration and living or working environment of nearby residents.Study on the aerodynamic noise of wind turbines has important theoretical significance and engineering application value.The theoretical basis of the study is introduced,including Acoustics Perturbation Equation,Actuator Line Model,BPM semi-empirical noise model of wind turbine.Then new model of this paper,Aeroacoustics Propagation Simulation of Wind Turbines Array based on APE with Sources Combination of ALM and BPM Models,is introduced.Perfect Matched Layer method is used because of the high requirements of non-reflection boundary condition in acoustics simulation.Simulations on point sound source and aeroacoustics noise by the flow past a circular cylinder are conducted.PML method is used to guarantee the non-reflecting condition of computation.The underlying approach is based on the hydrodynamic/acoustic splitting technique where the incompressible flow is first computed and acoustic field is computed with the sound source from incompressible flow.The computation results are studied and compared with Stokes' s law of sound attenuation,experiments and simulations results of literature.Because of the strict requirement of non-reflection boundary in acoustic field calculation,the PML boundary condition is compared with the traditional non-reflection boundary condition in this paper.PML boundary condition dissipates the fluctuation of parameters by mathematical method.Compared with the traditional non-reflective boundary condition,PML boundary condition has better non-reflective effect and is used in the calculation of acoustics simulation of wind turbines in the following paper.Then,the sound source is obtained with the combination of Actuator Line Model(ALM)and BPM Model,and added to the Acoustic Perturbation Equation,to calculate the aeroacoustics noise of NREL5 MWRef wind turbine,with the Perfect Matched Layer boundary condition.The underlying approach is based on the hydrodynamic/acoustic splitting technique where the incompressible flow is first computed and acoustic field is computed with the sound source from incompressible flow.The flow field of turbine is conducted with ALM,with the added Airfoil sound source of BPM model,the advantages of two sides are combined for the simulation of Wind Turbine's sound field.Then,the analysis of wind turbines' noise reduction is conducted based on two kinds of sound sources.