Research On Aerodynamic Performance Of Horizontal Axis Wind Turbine Blades With Trailing Edge Flaps

The blade of wind turbines is the core component in the process of wind energy conversion system.The flow field characteristics,pressure coefficient distribution and lift and drag coefficient of airfoils determine the performance of wind turbine blades,which is crucial to energy conversion efficiency.The structure of trailing edge flaps has attracted wide attention because of its outstanding lift-increasing effect and simple structure feature.However,current research on trailing edge flaps mainly focuses on two-dimensional structure analysis.The movement of blades is three-dimensional rotation,so it is of great significance to do three-dimensional research on trailing edge flaps.Based on two basic wind turbine airfoils NACA64418 and S809,this paper studies the influence of the trailing edge flap structure on the aerodynamic characteristics with the combination of numerical simulation and experimental verification.Though two-dimensional and three-dimensional analysis,this paper achieves the overall improvement of wind turbine performance and wind energy conversion efficiency.The main research contents and results are as follows:(1)Numerical simulation and experimental verification are used to analyze wind turbine airfoils NACA64418 and S809.The analysis conditions are under 500,000 and 750,000 Reynolds numbers and-10° to 20° angle of attack.The flow field characteristics,pressure coefficient and lift and drag coefficient of the two airfoils are compared and studied.Finally,based on the analysis results,NACA64418 airfoil is selected for subsequent research on trailing edge flap structure.(2)The study is conduct on the structural parameters of NACA64418 airfoil flaps.The influence of trailing edge flap deflection angle and trailing edge flap length on aerodynamic performance has been investigated.Lift-drag force characteristic of 10% trailing edge flap length and with the trailing edge flap deflection angle 10° are better than other models.Moreover,the change of the flap structure has no effect on the optimal operating attack angle of the airfoil.The optimum operating condition of attack angle is 6° for both the basic airfoil and flap airfoils.(3)Combined with experiment and numerical simulation,the NREL VI S809 wind turbine rotor is modeled and simulated to verify the calculation model.The wind turbine rotor with trailing edge flap structure at blade tip is compared with the original one to analyze the influence of flap structure on the flow field characteristics around the blade.The results show that,compared with the original blade,NACA64418-S809 composite airfoils blade can slightly improve the overall performance of the wind turbine blade.The power output of composite airfoils wind turbine rotor with flap structure is larger than that rotor without flap.At the wind speed of 10m/s,the power output of the wind turbine rotors all reaches the maximum value.The maximum output of rotor is the model with 20% blade length of trailing edge flap,which is 2% higher than that of other rotors.