Aerodynamic Control Using Windward-Surface Plasma Actuators on a Separation Ramp

Wind-tunnel experimentswere conducted on a 47-deg sweep, scaled 1303unmanned air vehiclemodel to assess the performance of an innovative windward-surface plasma actuator design for flight control at low angles of attack. Control was implemented by altering the flow past an aft separation ramp on the windward side using a single dielectric barrier discharge plasma actuator. The influence of ramp-expansion angles (20, 30, and 40 deg) on the plasma actuator’s ability to affect flow separation and aerodynamic lift was examined. Both steady and unsteady actuations of the plasma actuator were examined, and their effects were captured using lift measurements and flow visualizations. Results reveal that the plasma actuator effects are highly dependent on the ramp angle and actuator parameters such as duty cycle and modulation frequency. The actuators produced significant shifts in the lift curve, up to 25% for the most effective ramp angles of 20 and 30 deg, in the 0–20-deg range. Flow visualization results confirmed that the plasma actuator causes theflow to reattach over a region downstreamof the separation ramp. For all ramp cases examined, the unsteady (pulsed) actuator was more effective than the steady actuator in controlling flow separation and influencing the aerodynamic lift. The aerodynamic effect of plasma actuators was found to be highly dependent on the ramp angle and the separation strength over the ramp. Significant control forces were obtained using windward-surface plasma actuators and, indirectly, these control forces can be implemented to generate substantial control moments for maneuvering air vehicles.