Analysis Of Aerodynamic Performance And Study On Modification Method Of DU Airfoils Of Wind Turbine Blade

As the power of wind turbines continues to increase,the size of the blades is also getting larger,and the requirements for the strength and aerodynamic performance of the blades of wind turbines are also becoming higher and higher.The development of new airfoil families is difficult,investment is large,and the cycle is long.Based on the existing airfoil,it is of great research and engineering value to improve the aerodynamic performance of the airfoil by modifying the airfoil trailing edge or installing additional structures.In this paper,the influence of the symmetric thickening of the Gurney flap and the trailing edge on the aerodynamic performance of the airfoil is studied using computational fluid dynamics methods.Based on the advantages of the two airfoil modification methods,an airfoil trailing edge arc thickening method is proposed and predicted Its aerodynamic performance.First,numerical methods are used to predict the aerodynamic performance of the airfoil.By comparing and analyzing the calculated and experimental values of airfoils under different turbulence models,a reasonable turbulence model is selected.In this paper,the turbulence model of Transition k-ω SST four equations is selected as the calculation model.This model is a combination of the transition model and the k-ω SST turbulence model,which is suitable for predicting the aerodynamic performance of smooth airfoils.Calculate the aerodynamic performance of airfoils installed with Gurney flaps of different heights.The flap height ranges from 1% chord length to 3%chord length.The aerodynamic characteristics of the airfoil with Gurney flaps are analyzed,including the airfoil lift resistance,pressure and flow field distribution characteristics.The calculation results show that the Gurney flap can effectively raise the lift coefficient of the airfoil,and the lifting effect increases with the height of the flap.Gurney flaps also increase the pressure difference between the suction surface and the pressure surface of the airfoil.The pressure on the suction surface is lower than the original airfoil and the pressure on the pressure surface is higher than the original airfoil.Especially at the trailing edge of the airfoil,the Gurney flap has the most obvious effect of increasing the pressure difference.Secondly,the power function method is used to carry out symmetrical thickening modification on the airfoil trailing edge.The CFD method was used to calculate the aerodynamic performance of the trailing edge symmetrical thickened airfoil with different relative thickness.The effects of the thickening of the trailing edge on the airfoil resistance,pressure coefficient distribution and flow field distribution,and the relationship between the thickening of the trailing edge and aerodynamic characteristics were comprehensively studied.The influence of the trailing edge symmetrical thickening method on the aerodynamic performance of airfoils with different relative thicknesses was analyzed.From the perspective of aerodynamics,the effects of the surface pressure and flow field distribution of the symmetrical thickened airfoil on the lift on the lift characteristics are described.Finally,a new airfoil modification method,called the trailing edge arc thickening method,was proposed combining the characteristics of the increased lift of the airfoil by Gurney flaps and the strength of the symmetrical thickened airfoil structure at the trailing edge.In this method,the upper airfoil of the airfoil is unchanged,and the trailing edge of the lower airfoil is thickened by a power function.The characteristics of the lift coefficient and drag coefficient of the airfoil with different modified starting positions and different trailing edge thicknesses were analyzed systematically with the angle of attack.The mechanism of pressure distribution and flow field distribution of the airfoil surface with different modified start positions and different trailing edge thicknesses was comprehensively studied.The influence of power exponent n on airfoil lift resistance characteristics in the modified formula is also explored.