EXPERIMENTAL INVESTIGATION OF DBD PLASMA ACTUATORS DRIVEN BY REPETITIVE HIGH VOLTAGE NANOSECOND PULSES WITH DC OR LOW-FREQUENCY SINUSOIDAL BIAS

Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on DC or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. The experiments and computations showed vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted. The significance of charge build-up on the dielectric surface was demonstrated. Based on the observations, a new voltage waveform, consisting of high-voltage nanosecond repetitive pulses superimposed on a highvoltage low-frequency sinusoidal voltage, was proposed. Advantages of the new voltage waveform were demonstrated experimentally.