Experimental investigation of the properties of a glow discharge used as plasma actuator applied to rarefied supersonic flow control around a flat plate

Abstract

This paper describes experimental investigations focused on the glow discharge created by a plasma actuator and used to shock wave modification over a flat plate in a Mach 2 air flow. The model is equipped with a plasma actuator composed of two electrodes. A weakly ionized plasma is created above the plate by generating a glow discharge with a negative dc potential applied to the upstream electrode. ICCD images of the discharge without and with the Mach 2 flow show the influence of the flow field on the discharge morphology. In addition, ICCD images of the modified flow revealed that when the discharge is ignited, the shock wave angle increased with the applied voltage. Thermal measurements of the flat plate surface carried out with an IR camera showed that the spatial temperature distribution is not uniform along the plate and its maximum, near the leading edge, increases with the applied voltage. Previous results showed that surface heating is responsible for roughly 50% of the shock wave angle increase, meaning that purely plasma effects must also be considered to fully explain the flow modifications observed. The focus of this paper is the study of the properties of the glow discharge to better understand the interaction between the supersonic flow and the purely plasma effects which are responsible of flow field modifications, in particular ionization degree and thermal disequilibrium upstream the model. U 1 = 511 m.s -1 M 1 = 2  1 = 0.375 mm q m = 3.34e -3 kg.s -1 2.2 FLAT PLATE AND PLASMA ACTUATOR A schematic view of the experimental arrangement is presented on Figure 2. The model under investigation is a flat plate mounted in the test section, 174 mm downstream the nozzle exit. The flat plate is made of quartz with 100 mm long, 80 mm wide, and 4 mm thick and presents a sharp 672 R. Joussot and V. Lago: Experimental Investigation of the Properties of a Glow Discharge used as Plasma Actuator