DBD PLASMA ACTUATOR DRIVEN BY A COMBINATION OF LOW FREQUENCY BIAS VOLTAGE AND NANOSECOND PULSES

DBD plasma actuators driven by repetitive nanosecond pulses added to low frequency bias voltage are studied, and parametric results of plasma-induced thrust versus voltage profile parameters are presented. The results of the thrust measurements agree with schlieren visualization results obtained earlier and indicate that dielectric surface charge plays a major role in the thrust. Direct measurements of the dielectric surface potential and its dynamics show that charge builds up at the dielectric surface and extends far downstream of the plasma. For a sinusoidal voltage waveform, the dielectric surface charges positively. With the voltage waveform consisting of nanosecond pulses superimposed on a dc bias, the sign of the dielectric surface charge is the same as the sign (polarity) of the bias voltage. Based on the surface charge measurements, a modified configuration of DBD plasma actuator is proposed. Preliminary experiments show its effectiveness at relatively low voltages. Variations of the permittivity of dielectric with temperature and frequency were also considered in relation to their role in DBD actuator performance.