EXPERIMENTAL INVESTIGATION OF PLASMA FLOW CONTROL ON A FLYING WING MODEL BASED ON MICROSECOND PULSED EXCITATION

In order to improve the aerodynamic performance of flying wing layout aircrafts at high attack angles , an experimental study of microsecond pulsed dielectric barrier discharge (μs-DBD) plasma flow control was carried out in low-speed and transonic wind tunnels, using both full and half models of a flying wing. Flow visualization and force measurements are deployed to reveal the main mechanisms of plasma flow control and, to analyze the effects of excitation frequency and voltage on the stall characteristics of the flying wing model. The effectiveness of μs-DBD plasma in manipulating low-speed to subsonic flows is successfully verified, with the highest test Mach number and Reynolds number tested being 0.6 and 3.05×10⁶, respectively. Results show that μs-DBD plasma perturbs the model airfoil flow field by unsteady micro-scale compressive wave. These wave perturbations weaken the front separation vortex of the model and suppresses the flow separation by frequency coupling, thus leaving dimensionless frequency as a key parameter which influences the effectiveness of plasma flow control. In a low-speed wind regime (wind speed: 30 m/s), the optimal dimensionless frequency range is 0.35 to 1.06, accompanied by more than 25% in the maximum lift coefficient and 4 degrees postponement in the stall attack angle. As a comparison, in the transonic regime of Mach 0.6, the favorable dimensionless frequency drops to 0.22 and 0.44, with the maximum lift coefficient increased by 4.72% and 4.77%, respectively, and the stall attack angle postponed by 1 and 2 degrees, respectively. Additionally, since the excitation voltage of plasma affects the intensity of the compressive wave perturbation, the higher the excitation voltage is, the better the effect of plasma flow control will be.