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Load control on a dynamically pitching finite span wind turbine blade using synthetic jets



The feasibility of active flow control, via arrays of synthetic jet actuators, to mitigate hysteresis was investigated experimentally on a dynamically pitching finite span S809 blade. In the present work, a six-component load cell was used to measure the unsteady lift, drag and pitching moment. Stereoscopic Particle Image Velocimetry (SPIV) measurements were also performed to understand the effects of synthetic jets on flow separation during dynamic pitch and to correlate these effects with the forces and moment measurements. It was shown that active flow control could significantly reduce the hysteresis in lift, drag and pitching moment coefficients during dynamic pitching conditions. This effect was further enhanced when the synthetic jets were pulsed modulated. Furthermore, additional reduction in the unsteady load oscillations can be observed in post-stall conditions during dynamic motions. This reduction in the unsteady aerodynamic loading can potentially lead to prolonged life of wind turbine blades. Copyright © 2014 John Wiley & Sons, Ltd.