Experimental Investigation of Flameholding in Scramjet Combustor by Pylon with Plasma Actuator Based on Q-DC Discharge

This paper presents the results of testing and optimization of a plasma-assisted combustion scheme based on a pylon for fuel injection equipped with a plasma actuator. Electrodes were installed behind the stern of the pylon for the creation of Q-DC discharge with voltage U = 200–2500 V and current I = 3–7.5 A. The experiments were performed in the PWT-50 supersonic wind tunnel of the JIHT RAS under the following conditions: Mach number M = 2, static pressure ~200 Torr, stagnation temperature T0 = 300 K. Gaseous fuel ethylene was used and the fuel mass flow rate was 0.5–4 g/s. The pylon had a streamlined shape that prevented the formation of a stagnant zone; plasma-assisted combustion was performed under more difficult conditions compared to plasma-assisted combustion on a flat wall, where separated flows near the wall are easily formed by discharge. In this work, two new geometries of pylon equipped with electrodes were proposed and experimentally tested. A second version providing a longer discharge length demonstrates stable ignition and intense combustion in a fully discussed fuel mass flow rate. The process of ignition in a supersonic flow and flame front pulsations was described. A reduction in the energy input in comparison with the previously considered configurations of plasma-assisted combustion was also demonstrated.