Flow Separation Control by Plasma Actuator with Nanosecond Pulsed-Periodic Discharge

This paper presents a review of data on controlling the boundary layer attachment by a plasma actuator with high-voltage pulsed-periodic nanosecond excitation. Actuator-induced gas velocities show near-zero values for nanosecond pulses. The measurements performed show overheating in the discharge region at fast (tau similar or equal to 1 mu s) thermalization of the plasma inputed energy. The mean values of such heating of the plasma layer can reach 70, 200, and even 400 K for 7-, 12-, and 50-ns pulse durations, respectively. The emerging shock wave together with the secondary vortex flows disturbs the main flow. The resulting pulsed-periodic disturbance causes an efficient transversal momentum transfer into the boundary layer and further flow attachment to the airfoil surface. Thus, for periodic pulsed nanosecond dielectric barrier discharge, the main mechanism of impact is the energy transfer to and heating of the near-surface gas layer. The following pulse-periodic vortex movement stimulates redistribution of the main flow momentum. The experiments performed here have shown high efficiency of the given mechanism to control boundary layer separation, lift, and drag force coefficients, and acoustic noise reduction in the Mach number range of 0.05 to 0.85.