Improved Erosion Wear Model For Wind Turbine Blade Coatings

With the rapid development of wind power,during the operation of wind turbine,due to the wind and sand environment and other natural factors,the coating on the surface of wind turbine blade will be eroded by wind and sand,which will lead to coating spalling and exposure of substrate material,reducing the operation efficiency of wind turbine and even leading to downtime.Therefore,this paper is based on the erosion and wear experimental data of real wind turbine blade flat specimens in wind and sand wind tunnel,combined with the general erosion model form in Fluent for least squares fitting,to get a improved erosion model,and carry out numerical simulation of flat specimens for comparison and verification,and apply the model to S809 wing and NREL Phase VI two-blade wind turbine to investigate the erosion characteristics under the improved erosion model,and the main research work is shown below:Firstly,to verify the reliability of the improved erosion model,erosion calculations were performed on the test plate,and the following conclusions were obtained: under the comparison of different erosion conditions,the deviation of the maximum erosion rate at different impact velocities,different particle diameters and different impact angles was less than 20%,which illustrated the reliability of the improved erosion model.And for the improved erosion model,with the increase of impact speed,the erosion rate of both single particle and multi-particle increases exponentially(n=1.765);with the increase of impact angle,the erosion rate of single particle reaches the maximum at 15-20°,while the erosion rate of multi-particle reaches the maximum at about 30°;with the increase of particle diameter,the erosion rate of single particle increases exponentially,while the erosion rate of multiparticle increases exponentially when the particle diameter increases by 200μm.The single-particle erosion rate increased exponentially with increasing particle diameter,while the multi-particle erosion rate increased slowly in the range of 200μm.Secondly,the improved erosion model was applied to the S809 airfoil for erosion calculation and analysis,and the following conclusions were obtained:the S809 airfoil is an asymmetric airfoil,and the total erosion rate is greater for positive than negative angles of attack in the large angle of attack case;in the small angle of attack case,the positive erosion rate is less than the negative angle of attack,but less than the 0° angle of attack.Different erosion characteristics also appear at positive and negative angles of attack.At 15°angle of attack,the minimum value of erosion rate appears near the leading edge,while at-15° angle of attack,the minimum value of erosion rate appears near the trailing edge;at 20° angle of attack,the maximum value of erosion rate appears near the trailing edge of the pressure surface,while at-20° angle of attack,the maximum value of erosion rate appears in the middle part of the suction surface.With the increase of particle diameter,when the particle diameter is less than 200μm,the increase of particle diameter leads to the rapid increase of the erosion rate due to the enhanced carrying effect of the fluid on the particle,and near the increase of particle diameter to 200μm,the position of the particle collision to the airfoil surface is basically unchanged,which leads to the slow growth of the erosion rate,and the change of particle diameter does not cause the change of the maximum and minimum erosion position on the airfoil surface.Finally,the improved erosion model was applied to NREL Phase VI twoblade wind turbine and combined with the results of S809 airfoil for erosion calculation and analysis,and the following conclusions were obtained: the blade erosion range is mainly concentrated in the blade pressure surface and leading edge,while there is a small range of erosion near the suction surface near the leading edge and trailing edge point,and the closer the blade tip airfoil section,the greater the degree of erosion,at r/R=0.5.When r/R=0.5,the erosion is the most serious;with the increase of the blade tip speed ratio,the erosion area of the whole pressure surface decreases,while the erosion range of the suction surface near the leading edge increases.With the increase of particle diameter,blade surface erosion degree increases,especially concentrated in the leading edge of the blade;along the blade axial direction,from the root to the tip,erosion rate gradually increases.