Experimental investigation of flameholding in a cavity-based scramjet combustor by a multi-channel gliding arc

Abstract

A multi-channel gliding arc (MCGA) plasma with 4973 W of the average power was utilized to promote flameholding in an ethylene-fueled scramjet combustor with an inflow of Ma2.92. Schlieren, photography, and CH* chemiluminescence coordinated with electrical and pressure measurements were used to examine the effect of the MCGA plasma on flameholding. The results show that the flame can be basically held by the plasma in the presented experimental conditions, whereas the flame gradually spreads backward in the mainstream and is blown out eventually without the plasma. The MCGA plasma is able to re-ignite the fuel/air mixture with a short period, and the unstable combustion is more likely to be kept by the MCGA plasma for a longer period. The average flameholding time is increased by 51% when the plasma is added. A plausible flameholding mechanism for the flame promoted by the MCGA plasma is revealed that the temperature in the cavity is enhanced by the heat and kinetic effect of the MCGA plasma, decreasing the ignition delay time of the fresh fuel near the cavity ramp, which strengthens the flame stability.