Electrohydrodynamic Force and Acceleration in Surfaces Discharges

Abstract

The use of atmospheric pressure surface discharges as actuators for drag reduction, flow control, flow acceleration and flow re-attachment has been considered and studied over the past decade. There is still, however, a lack of clear understanding of the qualitative effect of these surface discharges on the flow and the potential and limits of this effect need to be quantified. In this paper, we use a fluid model to describe the space and time evolution of the plasma and of the force exerted on the neutral molecules in surface dielectric barrier discharges in configurations that have been proposed as actuators for flow control. The results show that for ramp or sinusoidal voltage waveforms, the discharge consists of large amplitude short current pulses during which a filamentary plasma spreads along the surface, separated in time by long duration, low current discharge phases of a corona type. The contribution of the low current phases to the total force exerted by the discharge on the gas may be dominant because their duration is much longer than that of the current pulses and because the force acts over a much larger volume. A description of the different discharge regimes and a parametric study of the electrohydrodynamic (EHD) force as a function of voltage rise time is presented.