Plasma actuation for leading edge separation control on 300-kW rotor blades with chord length around 1 m at a Reynolds number around 1.6 x 106

The second field test of a plasma-assisted 300-kW wind turbine was performed to investigate the flow-control authority of plasma-actuation technology at Reynolds numbers (Re) exceeding 10(6). The turbine rotational speed was regulated via pitch activation in the power-saving operation mode to limit Re to approximately 10(6). Additional generator-torque control was adopted to make the angles of attack exceed those allowable via original control. The leading-edge plasma electrode was activated at 10-min intervals and turbine characteristics with and without plasma actuation were compared using 1-min-averaged SCADA data, including wind conditions measured by a nacelle anemometer, obtained during a 6-day test. Results of this study reveal that the tip speed ratio (TSR) reduces under high-wind-speed conditions owing to additional torque control. Further, the power coefficient drops in the low TSR operating range, and improves upon plasma actuation. This has been statistically proven for at least one TSR bin. This result implies the existence of leading-edge separation under the additional torque control, and that plasma-actuation technology can effectively control the flow in the 1.6-1.8 x 10(6) Re range. Results of this study demonstrate the potential of and need for further investigation of the proposed technology to facilitate its application for multi-megawatt wind-turbine.