Experimental investigation of dynamic stall flow control for wind turbine airfoils using a plasma actuator

Because of the deterioration of aerodynamic performance of airfoils due to the dynamic stall of large wind turbine blades, a miniaturised remote-wireless-controlled actuating power supply and dielectric barrier discharge plasma actuator based on car-sticker technology were developed in this study. An experimental investigation of the plasma flow control of airfoil dynamic stall was carried out using dynamic pressure synchronous measurement and electronic external trigger Particle Image Velocimetry tracking acquisition. This study demonstrated that plasma aerodynamic actuation can effectively control the airfoil dynamic stall, reduce the strength of the dynamic separation vortex, improve the average aerodynamic force, increase the aerodynamic efficiency and reduce the hysteresis loop region when the aerodynamic force varies with the angle of attack, especially under both positive stroke and negative stroke. The average lift coefficient is increased by 7.1%, the stall angle of attack is delayed by 1.3 degrees, and the hysteresis loop region is decreased by 4.5%; at the angle of attack of 4 degrees-9 degrees, the plasma actuator reduces the average drag coefficient of the airfoil by 44.5%. The flow mechanism was also revealed. The actuator induces vortexes close to the suction surface, shaping a "virtual bulge" and affecting the downstream flow; the flow momentum in the boundary layer is then increased and a low-pressure region is generated that promotes the dynamic separation flow reattaching to the airfoil surface. This report will provide a new strategy for applying plasma flow control technology to improve the efficiency of large wind turbine blades. (C) 2019 Elsevier Ltd. All rights reserved.