| The blades of wind turbines in wind-sand environment for a long time will produce serious wear,which not only affects the stability of energy output of wind turbines,but also reduces the service life of blades.Therefore,it is of great significance to study the erosion wear of wind turbine blades on the wear resistance and reliability optimization design of wind turbine blades.In this thesis,firstly,the discrete element method combined with Fluent and EDEM is used to simulate the erosion wear behavior of the wind turbine in the sand environment.By analyzing the erosion wear characteristics of wind turbine blades under various working conditions,the influence of particle shape and different gravel concentration on the erosion wear of wind turbine blades was studied.Secondly,combined with the leading edge wear conditions of wind turbine blades during the service period of wind farm,the EDEM-Fluent coupling method was used to analyze the lift and drag curves and flow field characteristics of the NACA64 airfoil leading edge modification,to study the influence rule of leading edge wear on aerodynamic characteristics of the airfoil.The main conclusions are as follows:(1)When the particle shape is non-spherical(Φ<1),large wear occurs on the leading edge of the blade.The torque and power of wind turbine blades increase first and then decrease with the increase of particle shape factor,and the power and torque of wind turbine blades corresponding to non-spherical particles(Φ<1)are larger than those of spherical particles(Φ=1).(2)The amount of blade wear increases with increasing particle concentration and the wear at the leading edge of the blade with different particle concentrations is relatively serious.When the particle concentration is 2.30mg/m~3·s,the wear range is mainly concentrated in the leading edge and tip of the blade and shows a point distribution and sparse dispersion;When the particle concentration is 8.38mg/m~3·s,the wear shows flake distribution and compact dense;when the particle concentration is 14.03mg/m~3·s,the wear shows a large area of flake distribution and gradually diffuses to the tip of the blade along the radial direction.At the same time,the tangential force and normal force of the blade increase with the increase of particle concentration.(3)When the wind sand with different mass concentrations flows through the surface of the wind turbine blade,the minimum pressure stagnation point is generated at the leading edge of the airfoil,and the pressure difference between the pressure surface and the suction surface is the largest at the 97.83%section of blade tip along the radial direction of the blade.The drag coefficient curve and lift coefficient curve of each section airfoil of the blade at different concentrations gradually decrease at 19.13%r-61.65%r,and gradually increase at61.65%r-97.83%r;The blade torque and power increase with the increase of particle concentration.(4)Compared with the grit holes and small pits,the leading edge delamination has more significant effect on lift and drag coefficients of the airfoil.At a larger angle of attack,the increase of the drag coefficient of the airfoil and the decrease of the lift coefficient gradually increase.The leading edge wear of the airfoil will cause the separation point of the pressure surface trailing edge boundary layer to move forward.The ladder formed by the leading edge delamination on the airfoil surface will cause the airflow that has been attached to the surface to separate first and then attach,while the sand holes and small pits have little effect on the airflow. |
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