Electrohydrodynamic gas flow in a positive corona discharge

Abstract

When a sufficient high voltage is applied between a point and a plate in atmospheric air, a corona discharge is ignited and an electrohydrodynamic (EHD) force can be produced, resulting in an ionic wind of a few meters per second flowing from the point toward the plate. In this study, we aimed at characterizing the ionic wind EHD flow produced by DC positive point-to-plate corona discharges. This is realized with the help of a high-speed particle image velocimetry system and Schlieren visualizations. The obtained measurements allowed us to characterize precisely the ionic wind vs time, as well as its dynamics when the discharge is switched on. We highlighted the key role of the breakdown streamers in the ionic wind hydrodynamics. We discovered that, in the presence of breakdown streamers, the positive corona discharge produces a pulsed ionic wind whose frequency corresponds to the frequency of the current pulses. To explain this EHD result, we investigated and showed that each single current pulse is composed of several streamers or several branches of one streamer, this phenomenon being at the origin of a space charge mainly composed of positive ions. Finally, we highlighted that when the steady breakdown streamer regime takes place, the time-averaged current becomes greater than the theoretical values given by Townsend's law since it evolves nearly linearly with the high voltage.

Discharge Stability Enhancement in Surface Corona Actuators

“…Streamers may appear either individually or in a series of 2 or 3 subsequent pulses of decreasing peak intensity, but always according to the scales above. The shape and timing found in these experiments are similar with those reported in a recent work from Moreau [22] in which the authors investigated a needle-plate volumetric configuration powered in DC under equivalent discharge conditions.…”

“…Viscosity and diffusion may then cause a progressive weakening of fluctuations for increasing x distances. This is in fact compatible with the findings on a 3D needleplate case [22] which -as stated in § III-A1 -shares some commonalities with the present surface discharge. Similar properties have been also described for the pulsed ionic wind in DBD actuators [27].…”

Electric wind generation by nanosecond repetitively pulsed microplasmas

“…Furthermore, the velocity reaches zero at the plate, as expected for fluid flow but not in the case of electrostatic precipitation (Defoort et al 2018). A recent study of the ionic wind produced by a corona discharge has shown a strong agreement between time-resolved Schlieren photographs and PIV velocity fields (Moreau et al 2019).…”

Partial Discharge Imaging Correlated with Phase-Resolved Patterns in Non-Uniform Electric Fields with Various Dielectric Barrier Materials

“…The progress was related to introduced space charge and subsequent forms of discharges, such as streamer and leader. If a sufficiently high voltage is applied between a point and a plate in atmospheric air, a corona discharge is ignited, resulting in an ionic wind flowing between electrodes [5]. The corona effect and streamer propagation in the point to plane configuration are also subject of a numerical modeling (e.g., [6,7]).…”