The Research On The Application Of Trailing Edge Flaps In Large Low Wind Speed Wind Turbines

Wind energy is leading the transformation of the global power system and becoming one of the most reliable clean energy sources in the world.It is an inevitable trend to develop large and efficient wind turbines to improve the wind utilization efficiency at low wind speeds.At present,the flap control technology has become an effective measure to improve the power of the wind turbine because of its simple structure and remarkable effect of increasing lift.In order to research the effect of flap on the aerodynamic performance of the low-wind-speed wind turbine,the Gurney flap technology is researched by using two blade stall Phase VI wind turbine as a model.Then,based on the passive flow control technology of the flap of Gurney,the influence of the active control technology of the trailing edge flap on the aerodynamic performance of the large wind turbine was researched for the 5MW wind turbine developed by NREL.The details are as follows:1?Taking the Phase ? wind turbine as the research object,the modified wind turbine model with different heights of Gurney flaps was built.The SST k-? turbulence model was used to calculate the modified wind turbine.The wind turbines before and after the retrofit were compared and analyzed.The output torque,blade section pressure and flow field structure show that the output torque of the modified wind turbine has changed significantly,and the flap height is 1%C?3%C(C is the airfoil chord length).The wind wheel torque at each wind speed is obviously increased,and the Gurney with a height of 3%C has the best increase effect;when the flap height is 4%C?6%C,the modified wind wheel torque is instead It is lower than the torque of the wind turbine without the flaps;the increase effect of the Gurney flaps increases first and then decreases with the increase of the wind speed;when the flaps are damping,the flaps increase with the increase of the wind speed.The damping effect continues to increase.2?Taking the NREL 5MW wind turbine blade section airfoil NACA64-A17 as the research object,the trailing edge flap was introduced and studied.The effect of the length of the flap on the aerodynamic characteristics of the airfoil is studied by numerical calculation method by ignoring the suction effect of the trailing edge flap.The calculations show that the trailing edge flaps with a length of 15%C have the best lifting effect when the incoming wind speed is 6m/s,11.4m/s and 20m/s.Under the condition of small angle of attack,with the increase of the incoming wind speed,the increase effect of the trailing edge flaps is also improved.3?Based on the above study,the trailing edge flaps were added to the tip of the blade at 70%R(R is the radius of the rotor)of the 5MW wind turbine blade.The length of the flap is 15%of the chord length of each blade of the blade,ignoring the suction of the trailing edge flap gap.The influence of the deflection angle of the flap on the aerodynamic performance of the wind turbine is studied by numerical simulation.With the increase of wind speed and deflection angle of trailing edge flap,the effect of flaps on the power of wind rotor increases first and then decreases.The wind speed was 3m/s?11.4m/s,and the output power of the wind rotor reached the maximum after the flap deflected 6°,8°,10°,14°,12°,12°,10°,8°,60 and 60 respectively.The trailing edge flap adjustment strategy prior to the rated wind speed is determined.The reason for the increase effect of the flap is to increase the airfoil camber and adjust the angle of attack of the blade section airfoil,so that the blade cross-section airfoil can reach the optimal angle of attack at each wind speed,increasing the lift and the tangential force.Therefore,the trailing edge flaps improve the aerodynamic performance of the wind turbine at low wind speeds and improve the wind turbine power output.In this paper,the influence of Gurney flaps and trailing edge flaps on the aerodynamic performance of wind turbines was studied,the raising mechanism of the flaps was revealed,and the active control technology of the trailing edge flaps was proposed to achieve the optimal power point tracking of large-scale wind turbines at low wind speeds.