Effect Of Sand Shape And Size Distribution On The Erosion Characteristics Of Wind Turbine Airfoil

With the gradual reduction of fossil energy and the increasing awareness of environmental protection,wind energy as a clean renewable energy source receive s great attention,and wind turbines have also been widely used.When the wind turbine is running in the wind-sand environment,wind turbine blades will be collided by the sand particles,causing the surface of the blade to erosion,affecting the power outp ut of the wind turbine and reducing the power generation of the wind turbine.Therefore,it is studied in this paper that the effect of sand particles on the erosion of wind turbine airfoil in the wind-sand environment,and provides a basis for the wind erosion design of wind turbine blades in the desert environment.In this paper,the NACA 0012 three-dimensional airfoil is used as the research object.The SST k-? turbulence model and the discrete phase model(DPM)are used to study the erosion characteristics and aerodynamic performance of wind turbine airfoil in the desert environment.The research content mainly includes the following two aspects:(1)the influence of the shape of sand particles on the airfoil erosion characteristics under different particles volume equivalent diameter;different angles of attack,particle mass concentration,and wind speed,the influence of particles shape on the range of critical particle Stokes of airfoil erosion;(2)Using UDF to load random particles with Gaussian distribution,and to study the influence of the size distribution of random particle size and single particle size on the airfoil erosion characteristics at different angles of attack;and the influence of random particles on the erosion and aerodynamic performance of the airfoil at different particle mass concentrations.The main conclusions are as follows:(1)When the flow velocity is 14.6m/s and the angle of attack is 6°,the influence of different shape factor particles on the variation of the maximum wear rate of the airfoil is basically the same.When the volume equivalent diameter of the particle increases gradually,the maximum erosion rate of the airfoil increases first,a small decrease occurs when the particle diameter is 80 ?m,and then increases as the particle diameter increases.When the particle volume equivalent diameter is the same,the maximum erosion rate of the airfoil is larger when the shape factor is less than 1 compared to the spherical particle(i.e.,the particle that shape factor is 1).The effect of particle shape on the airfoil erosion interval is small and almost negligible.As th e volume equivalent diameter of the particle increases,the erosion interval of the airfoil gradually expands from the vicinity of the airfoil leading edge to the airfoil trailing edge.For particles with different shape factors,the airfoil lift coefficie nt decreases first and then increases,and the airfoil resistance coefficient increases first and then decreases as the particle volume equivalent diameter increases.(2)The shape of the particles affects the range of the critical particle Stokes of the airfoil.At different angles of attack,the smaller the particle shape factor,the larger the number of critical particles Stokes at which the airfoil begins to erosion.As the angle of attack increases,the number of critical particles Stokes in which the airfoil wears increase.At different particle mass concentrations,the smaller the particle shape factor,the larger the critical particle Stokes number of the airfoil wear,but the change of particle mass concentration has no effect on the critical partic le Stokes number of the airfoil erosion.When the wind speed is different,the smaller the particle shape factor is,the less the airfoil is more likely to erosion.When the wind speed increases,the conclusion is still valid.In summary,under the same conditions,the smaller the particle shape factor,the larger the critical particle Stokes number of the airfoil erosion.(3)The particle size distribution has little effect on the airfoil erosion interval.When the size distribution of random particle and single size particle,the erosion interval of the airfoil surface expands from the airfoil leading edge along the pressure side toward the trailing edge as the increase of particle average diameter.The larger the angle of attack,the larger the airfoil er osion interval.The particle size distribution has a great influence on the degree of airfoil erosion.When the average diameter of the particles is the same,the erosion of the airfoil with single size particle is more serious than that of the random particles.When the particle mass concentration is small,the particle size distribution has little effect on the aerodynamic performance of the airfoil,which is basically negligible.(4)When random particles are the same particle size range,the particle mass concentration has little effect on the airfoil erosion interval,which is almost negligible,and the airfoil erosion interval is only related to the angle of attack and the particles average diameter.The particle mass concentration greatly affects the degree of erosion on the airfoil surface,and the maximum airfoil erosion rate is proportional to the particle mass concentration at the same random particles.At the same particle mass concentration,the addition of particles has little influence on the pressure around the airfoil than the clean air when the angle of attack is 9°,but it has a great influence on the pressure around the airfoil when the angle of attack is 12°,especially,near the trailing edge of the airfoil,and the influence on the positive pressure zone near the trailing edge of the airfoil gradually increases as the average diameter of the random particles increases,but the particle mass concentration has little effect on the pressure around the airfoil on the whole.The particle mass concentration also has little effect on the airfoil lift and resistance coefficient.The larger the particle mass concentration,the more obvious the effect of the particles on the airfoil lift and resistance.