High lift airfoil leading edge separation control with nanosecond pulse driven DBD plasma actuators

The efficacy of dielectric barrier discharge (DBD) plasmas driven by repetitive nanosecond (NS) pulses for flow separation control is investigated experimentally on an airfoil leading edge up to Re=1×10⁶ (62 m/s). The NS pulse driven DBD plasma actuator (NS-DBD hereafter) transfers very little momentum to the neutral air, but generates compression waves similar to localized arc filament plasma actuators. Experimental results indicate that NS-DBD plasma performs as an active trip at pre-stall angles of attack and provides high amplitude perturbations that manipulate flow instabilities and generate coherent spanwise vortices at post-stall angles. These coherent structures entrain freestream momentum thereby reattaching the normally separated flow to the suction surface of the airfoil. Such devices which are believed to function through thermal effects could result in a significant improvement over AC-DBD plasmas that rely on momentum addition which limits their performance at high speeds.