Control of boundary layer separation and the wake of an airfoil using ns-DBD plasma actuators

The efficacy of nanosecond pulse driven dielectric barrier discharge (ns-DBD) plasma actuators for boundary layer separation and wake control is investigated experimentally. A single ns-DBD plasma actuator is placed at the leading edge of a NACA 0012 airfoil model. Both baseline and controlled flow fields are studied using static pressure measurements, Particle Image Velocimetry (PIV) and Constant Temperature Anemometry (CTA). Experiments are primarily performed at Re = 0.74 x 10⁶ and α = 18°. CP, PIV and CTA data show that a forcing frequency of F⁺ = 1.14 is optimal for separation control. CTA surveys of the wake at x/c = 7 indicate three approximate regimes of behavior. Forcing in the range 0.92< F⁺ < 1.52 results in separation control over the airfoil and low frequency broadband reduction in the wake. Excitation in the range of 0.23 < F⁺ < 0.92 produces a single dominant frequency in the wake while F⁺ < 0.15 shows behavior consistent with an impulse response. PIV data confirm these observations in all three regimes. Cross-correlations of CTA data are also employed to evaluate the two-dimensionality of the excited wake. The initial results presented here are part of an ongoing effort to use active flow control, in the form of ns-DBDs, as an enabling technology for the study of unsteady aerodynamics.