Experimental investigation on the gliding arc plasma supported combustion in the scramjet combustor

Abstract A gliding arc discharge with an averaged power of 200 W at atmospheric pressure was used to support the supersonic combustion of ethylene fuel with an inflow speed of Mach number 2.92. The instantaneous wall pressure of the combustion chamber and the high-speed CH* chemiluminescence imaging were simultaneously measured to show the characteristics of the gliding arc plasma assistance combustion. The results show that the gliding arc increases the average wall pressure. Specifically, as for the fuel injector near the front step of the cavity, the wall pressure downstream of the aft ramp wall increased at different global equivalence ratios, even increasing the wall pressure upstream of the fore wall of the cavity at an equivalence ratio of 0.1. For the injector away from the fore wall of the cavity, the presence of the gliding arc promotes the wall pressure downstream of the aft ramp wall. In the presence of the gliding arc, the emission intensity and the area of the flame in the cavity are weakened at a low global equivalence ratio (0.10–0.12), whereas the effect is not significant at a range of the total equivalence from 0.15 to 0.2. In the high equivalence ratios from 0.22 to 0.29, the gliding arc plasma plays a significant role in combustion enhancement owing to an increase in the emission intensity and the area of the cavity flame.