Feasibility of Plasma Actuators for Active Flow Control over Wind Turbine Blades

Abstract

*Attempting to increase the power generated by wind turbines in order to meet a greater percentage of electrical demand has created new challenges in the area of flow control. It is hoped that plasma actuators will not only provide a feasible alternative to traditional mechanisms for flow control but actively aid in increasing power generation. The ability of plasma actuators to produce the necessary aerodynamic responses of active flow control in two potential applications was experimentally assessed. In the first application, an actuator was placed at the trailing edge in order to shift the lift slope of a blade section. This would be used as a means of severe gust alleviation in large turbines. Without any optimization, a single crude actuator produced a noticeable aerodynamic response for all small positive angles typical of large wind turbines tested. In fact, the single actuator’s response already exceeded the estimated required response based on a simple analytical model of an actual wind turbine. In the second application, aimed at smaller turbines, a leading edge actuator was utilized in an effort to delay and control the stall behavior allowing higher angles of attack to be utilized without increasing the chances of stall. Sensitivity studies were performed on both the applied voltage and the location of the actuator. While the actuator could increase the coefficient of pressure at high angles of attack and generate slightly more lift, there was little observable benefit in controlling stall behavior. In only one configuration did the actuator delay stall, while two configurations actually hastened the onset of stall. More precise experimental testing in the stall regime is required, but, the actuator in this application was largely unsuccessful in producing the desired aerodynamic response.