Research On Influence Of Blade Deformation On Aerodynamic Noise Of Wind Turbine

The fluid flow creates vortices,and the vortex motion accelerates to sound.aerodynamic noise not only causes environmental pollution,but also destroys the structure of the wind turbine and reduces the life of the wind turbine.The wind wheel is the most important part of the wind turbine to extract wind energy.Under the natural wind,the blade will be deformed.The deformation of the blade causes a change in the flow field around the wind turbine,which in turn affects the aerodynamic noise.Therefore,it is extremely important to study the influence of blade deformation on the aerodynamic noise of wind turbines.However,from the study of aerodynamic noise at home and abroad,scholars neglect or rarely consider blade deformation.the two-way fluid-solid coupling method is used to compare the deformation of solid wood and epoxy resin blades,study the causes and influencing factors of blade deformation,analyze the influence of blade deformation on the flow field,and then explore the blade deformation to wind turbine aerodynamic noise.Impact,providing reference for the research and design of high-efficiency and low noise wind turbine blades.The S-airfoil three-blade horizontal axis wind turbine is selected as the research object.The diameter of the wind wheel is 1.4m,the rated power is 300 W,the rated tip speed ratio is 5.5,and the rated wind speed is 10m/s.Using the Fluid Flow(CFX)and Transient Structural in ANSYS software,the bidirectional fluid-solid coupling calculation is carried out,and the output power of the solid wood material blade simulation is compared with the wind tunnel experimental results,and the error is within the allowable range.The main findings are as follows:Comparing the surface deformation of the two materials,it is found that the tip is the most deformed position: the maximum deformation of the blade tip of solid wood material is 18.7 mm,which is 4.8 times that of the epoxy resin blade;the blade root position deformation is the smallest,and the blade deformation of the two materials The average value is 0.1mm,which is almost negligible.From the stress study on the blade surface,the stress at the root position is the largest and the tip position is the smallest.The influence of the material characteristic parameters on the blade deformation is further analyzed: the elastic modulus is the deformation of the blade.The influence is the largest,and the influence of density and Poisson’s ratio is small.The deformation of solid wood materialblade increases with the increase of wind speed and tip speed ratio than that of epoxy resin material.Comparing the two material blades,the surface pressure difference of the solid wood material is 18 Pa higher than that of the epoxy resin,the loss of the wake speed is increased,and the blade surface and the wind wheel wake vorticity are larger.The turbulent energy of the blade at the rated wind speed is 0.0027m2/s2 larger than that of the epoxy resin blade.;the blade wind turbine output power of the solid wood material under the same working condition is larger.Comparing the two material blades,the sound pressure level,the absolute value of the pulsating pressure and the aerodynamic noise of the solid wood material blade are larger at each position;the sound pressure level difference under the same working condition is less than 1 d B;the sound pressure level of the same material is 0m to 0.3 in the axial direction.The change of m sound pressure level is different from the axial 0.4m to 1m.The sound pressure level from 0m to 0.3m in the axial direction has an increasing trend,and the sound pressure level is the largest at the radial position of 0.5m.The sound pressure level at the radial position is along with the axial direction.The increased sound pressure level of the distance first decreases and then tends to be gentle,wherein the sound pressure level at the radial position of 0.5 m is the largest at the axial 0 m sound pressure level,and the sound pressure level is larger as the wind wheel position is closer.As the wind speed and the tip speed ratio increase,the sound pressure level also increases,and the maximum difference between the sound pressure level of the solid wood material blade and the epoxy resin material does not exceed 0.5d B.In summary,the solid wood material blade has a larger deformation amount,the wind turbine output power is larger,the aerodynamic noise sound pressure level is larger,but the gap with the epoxy resin material blade is less than 1 d B,so the solid wood material blade is more suitable than the epoxy material blade for Small wind turbines.This paper can provide reference for designing high-efficiency and low noise wind turbine blades considering blade deformation.