Demonstration of Separation Control Using Dielectric Barrier Discharge Plasma Actuators

Active flow control of boundary-layer separation using dielectric barrier discharge (DBD) plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2%) and high (2.5%) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-array plasma actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Deliberately-detuned applied-voltage frequencies driving each electrode pair generated traveling waves with a forcing frequency that can excite the separated shear-layer instabilities, thus providing a control mechanism. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the DBD plasma actuator is an effective device for separation control