Characterization of electric discharge collocated with gas jet in supersonic airflow

The subject of this paper is a constricted electric discharge, generated over a mixing layer of ethylene (as a generic fuel) and carbon dioxide (as a product of combustion) directly injected into a supersonic airflow. The discharge location and plasma parameters are characterized based on optical spectral analysis, fast camera observation, and electrical probe measurements. It is shown that the discharge mostly locates within a zone of gas composition relevant to the mixing layer and drifts toward the core airflow in the case of carbon dioxide or stay in the area rich by secondary gas in the case of ethylene injection. The analysis of the experimental data demonstrates that the discharge behaviour is determined by the balance of thermal dissociation, dissociative thermal conduction and nonequilibrium ionization.