Investigation On Stall Control Of Wind Turbine Airfoil Based On Coflow Jer And Vortex Generator

In the process of wind turbine operation,because of wind shear,wind,wind direction changes,such as complicated operating environment,wind-power blades often appear stalling phenomenon.Study shows that the airfoil stall will dramatically reduce the wind energy absorption efficiency of blade and increase the blade load.Through airfoil flow control can effectively delay the airfoil stall angle,and improve the airfoil dynamic stall characteristics,which is of great significance for the safe operation of the wind turbine efficiency.Compared with the traditional airfoil,wind turbine airfoil usually has a larger relative thickness and leading edge radius,and is limited by the blade manufacture craft,usually using blunt trailing edge.But,the research about stall control for wind turbine airfoil is not perfect enough.Research chooses DU91-W2-250 and DU97-W-300 wind turbine airfoil as the research object,by means of CFD method,using S-A and SST k-co turbulence model.The numerical studies on airfoil stall contrl to the coflow jet and vortex generator was carried out respectively.The main results were as follows:(1)Under the static flow,the coflow jet can effectively improve the lift coefficient,reduce the resistance coefficient of airfoil,and delay the stall Angle of attack.As a result of the enhanced effect of circulation from coflow jet,the rising of drag reduction and flow separation inhibition effect increases with the injection speed and significantly enhanced.The coflow jet in the circulation channel surface has strong shear and turbulence of permeability effect with mainstream,and a large number of horizontal momentum is communicated to the mainstream in the boundary layer,enhance the downstream fluid state of adhesion and significantly improve the speed recovery of airfoil wake.When the coflow jet is large enough and under the small angle of attack will result in minus drag and acceleration of wake.(2)Under the cycle pitch motion state,coflow jet can effectively increase the dynamic lift coefficient of airfoil,delay the dynamic stall angle,and reduce the hysteresis effect of lift and drag coefficient.When the jet flow intensity is large enough,the dynamic stall was restrained effectively.But when the jet flow intensity is small,the flow will lose possess characteristics in airfoil downward swing process,accelerate the counter-rotating,lift coefficient fell sharply,the coflow jet lose efficacy.(3)Vortex generator on the suction surface flow vortex,speeds up the exchange of outside high-energy fluid and near wall flow energy,and resistance to adverse pressure gradient,which can effectively delay the airfoil steady stall angle of attack,increase the lift coefficient under large angle of attack,reduce the drag coefficient,improve the airfoil lift-to-drag ratio.(4)Vortex generator can effectively increase the lift coefficient,increase the dynamic stall airfoil angle of attack,to lessen the airfoil stall performance.But in the deep stall,the effect is weak.The thesis studied the stall contral of coflow jet and vortex generator for wind turbine airfoil by means of CFD method,and has certain engineering application value.