Hydrodynamics of a Water Droplet Impact on a Surface Dielectric Barrier Discharge Plasma*

Dielectric discharge barrier (DBD) actuators generate a non-thermal plasma discharge over a dielectric surface. This can be exploited for flow control, de-icing of aircraft wings, disinfection of surfaces, among other applications. An actuator consists of at least one pair of electrodes, where one is exposed to air and the other one is encapsulated by a dielectric material. When voltage is applied between the electrodes, the air surrounding the exposed electrode and the dielectric material becomes ionized, and a sheet of plasma is formed along the edge of the exposed electrode. In most flow control and de-icing applications, wing surfaces, turbine, and compressor blades on which DBD actuators operate are constantly exposed to humid environments. In particular, water droplets can impact the actuators during typical operations. It is thus needed to understand the dynamics as well as the multi-phase, multi-physics processes during droplet impact on an actuator. Our experimental work yielded consistent results on the spreading of the droplet, formation of glow and streamer plasma discharges within the droplet, and disruption on the otherwise smooth induced flow. These results are believed to be fundamental for flow control, de-icing applications, as well as other industrial processes.