| The separation of flow on the surface of wind turbine blades seriously restricts the wind harvesting ability of wind turbines,reducing their power generation efficiency.Using appropriate flow control methods to suppress blade flow separation can effectively improve the efficiency of wind turbines.The leading edge slat control method helps the fluid on the suction surface of the airfoil overcome viscous resistance,and the Gunny flap control method has unique advantages in overcoming the inverse pressure gradient of the airfoil.This article combines the leading-edge slat with the S809 airfoil profile feature and Gunny flap,and explores the influence of combined control methods on the aerodynamic characteristics of wind turbines.This article uses numerical simulation methods to explore the influence of combined control methods on the aerodynamic characteristics of S809 airfoils.Using the S809 airfoil as the main airfoil,a leading-edge slat with S809 airfoil contour features is added to its leading edge,and different positions and sizes of Gunny flaps are added to the tail edge of the main airfoil.By comparing the aerodynamic characteristics of airfoils with different geometric sizes of combined control methods,this study explores the impact of combined control methods on the aerodynamic characteristics of airfoils.Research has shown that the combination control method with a height of 0.03 c for the Gunny flap has better aerodynamic characteristics for the airfoil.The combined control mode can significantly improve the lift coefficient of the airfoil,and the fluid near the trailing edge of the airfoil can obtain higher velocity and kinetic energy to suppress the adverse pressure gradient and overcome the viscous drag of the fluid.Compared with the single flow control mode,the combined control mode combines the advantages of leading-edge slats and Gunny flaps,which can improve the pressure coefficient distribution of the two airfoils.The pressure difference between the two airfoil surfaces of the combined control mode airfoil is greater.On the basis of the above research,this article changes the leading-edge slat twist angle of the combined control method blades and explores the aerodynamic characteristics parameters of the combined control method blades at different wind speeds.By comparing the aerodynamic parameters of the combined control blade with the original blade,the conclusion is drawn as follows.At low wind speeds of 7 m/s,the combined control method has limited torque improvement for the blades.At high wind speeds,the combined control method can significantly increase the blade torque,and the torque value is proportional to the wind speed.The combined control method has a significant inhibitory effect on the flow separation of the blade suction surface.Compared to the original blade,the flow separation line of the combined control method blade lags behind or does not undergo flow separation.This article compares and analyzes the advantages of combined control methods compared to single control methods.The combined control method has a better effect on improving blade torque than a single control method.Under low wind speed conditions,the combined control method can better suppress the flow separation phenomenon on the blade surface,resulting in smaller separation vortices.The combination control method reduces the negative pressure gradient and range at the front edge of the blade suction on the one hand,and increases the pressure on the pressure surface on the other hand.The combination control method has a larger pressure difference on the blades to increase the blade torque.Compared to a single control method,the combined control method has unique advantages in improving the aerodynamic characteristics of blades.In this paper,the control mechanism of the combined control mode for the boundary layer flow separation of the wind turbine and its effect on the aerodynamic characteristics of the wind turbine are obtained,which provides a new idea for the design of the wind turbine. |
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