Gliding Arc Plasma-Controlled Behaviors of Jet-Wake Stabilized Combustion in a Scramjet Combustor

A multichannel gliding arc (MCGA) plasma is used to control the jet-wake stabilized combustion in a Mach 2.92 cavity-based and ethylene-fueled scramjet combustor. Optical diagnostic methods (including high-speed photography, schlieren, and planar laser-induced fluorescence with acetone tracer) combined with plasma kinetic simulations and Reynolds-averaged Navier-Stokes/large-eddy simulations were employed to investigate the combustion behaviors. The results show that the flame is mainly located near the cavity leading edge and operated at the jet-wake stabilized mode. When the MCGA plasma is added at the upstream wall of the cavity leading edge, the vigorous region of the flame spreads upstream 6.5 times longer than the original one without the plasma. Once the plasma is turned off, the flame returns back to the cavity leading edge. The species N-2* (Nitrogen in the excited state) and hydrogen atoms produced by the plasma are favorable for igniting the flame near the plasma, and the average penetration depth of the fuel above the plasma is increased by about 10%. Intense combustion near the plasma occurs with higher pressure, establishing the recirculation zone with the boundary-layer separation. The combined effects of the reactive species produced, the elevated temperature, and the modified flowfield induced by the plasma contribute to the MCGA-controlled behaviors of jet-wake stabilized combustion.