Nanosecond dielectric barrier discharge–based dynamic stall control on an SC-1095 airfoil

Abstract

Dynamic stall is a time-dependent flow separation and stall phenomenon that is present in many applications, including violently maneuvering aircraft, surging compressor, wind turbine, and, most observably, rotorcraft. Nanosecond dielectric barrier discharge plasma actuator has previously demonstrated the control ability in static stall conditions and shows promise to address dynamic stall. The present work explores the ability of nanosecond dielectric barrier discharge to control dynamic stall over an SC-1095 airfoil and summarizes the control law of actuation parameters. The actuation voltage, actuation frequency, and reduced frequencies were varied over large ranges: V_p–p = 7–13 kV, F⁺ = 0.5–10, and k = 0.05–0.15. Direct aerodynamic measurements were taken for each combination of actuation voltages and actuation frequencies, and fixed combination at different experimental reduced frequencies. It was observed that nanosecond dielectric barrier discharge could effectively improve the dynamic stall characteristics, and three major conclusions were drawn. First, there is a threshold for actuation voltage. Only when the actuation voltage is greater than or equal to the threshold voltage can the separation be effectively suppressed and the steep stall can be alleviated. Second, High F⁺ has better control performance of maintaining peak lift in the stall regime and achieves better effects in moment control and drag reduction while lift reattachment is better with low F⁺ on downstroke. Last, with the increase of reduced frequency, the control effect of nanosecond dielectric barrier discharge with settled actuation parameter combination becomes worse, so greater cost needs to be paid for effective control at a larger reduced frequency.