A Study of the Electrical Supply System of a Barrier Discharge for EHD Flow Acceleration

In the present work an experimental investigation on the EHD interaction effect, induced by means of a dielectric barrier discharge on a one atmosphere subsonic air flow, is described. The air flow is obtained in an open circuit blowing wind tunnel at different air speeds. A plane plasma panel equipped with a dielectric discharge barrier system is immersed into the flow. A single phase sinusoidal power supply system, a superposition of a single phase sinusoidal system with a DC voltage supply, and a three phase symmetrical power supply configuration are considered. Electric, fluid dynamic and spectroscopic diagnostic techniques are utilized. Pitot probe measurements are performed in the boundary layer on the plasma panel surface. Schlieren imaging to visualize the plasma sheath is done. Vibrational and rotational temperatures are evaluated by means of spectroscopic techniques. The force induced on the flow by the dielectric barrier discharge acts on the ions of the non-neutral sheath ahead of the plasma filament traveling on the panel surface. This cause a reduction of the time interval in which the force is active. The EHD effect and the momentum transfer to the gas flow in the boundary layer is reduced when the flow speed growths. An increase of the supply frequency and of the supply voltage cause an increase of the momentum transfer. In these experiments no significant increase of the efficiency of EHD effect is observed when utilizing the superposition of a DC voltage to a single phase power supply or a three phase power supply.