An experimental investigation of deep dynamic stall control using plasma actuators

The effect of active control by a nanosecond pulsed dielectric-barrier discharge plasma actuator was studied on a NACA 0012 airfoil, with a 7-inch chord (with 13-inch endplates) and a 14-inch span, for a sinusoidal motion profile from α = 0° to 20° at Re c = 300,000 and k = 0.075. Characterization of the baseline flow highlighted the dominant influence of the dynamic stall vortex (DSV) and the subsequent separation, during the downstroke, on the aerodynamic forces. PIV results confirmed that actuation over a wide range of frequencies generates structures of various size and spacing through the manipulation of the Kelvin–Helmholtz instability. The results showed that the dominant DSV, present in the baseline case, was replaced by the structures induced by actuation. The effects of control on the flow field were used to explain the changes in aerodynamic loading, providing insight into the underlying physics of the observed control authority. Peak aerodynamic loads (lift, drag, and moment) were all reduced by control. Control also augmented the lift during the downstroke (separated flow), reduced lift hysteresis (responsible for vibratory loading), and increased the cycle-averaged lift-to-drag ratio. Graphical abstract