Multi-channel gliding arc plasma-assisted ignition in a kerosene-fueled model scramjet engine

Abstract

A multi-channel gliding arc (MCGA) plasma was utilized to ignite a kerosene-fueled model scramjet engine with an inflow of Ma2.92. High-speed photography from the top and side view of the scramjet combustor, high-speed CH* chemiluminescence imaging coupled with the electrical measurements were used to investigate the ignition process. A three-dimensional RANS simulation was used to show the distributions of velocity, temperature, and local equivalence ratio of the supersonic cold flow. In the ignition process, the formation of the flame kernel mainly depends on the discharge characteristics of the MCGA plasma, whereas the flame propagation process is mainly determined by the cavity flow. The MCGA plasma is more likely to produce a large area of the flame kernel in the spark-type discharge with the long arc column and overlaps of each channel gliding arc. The larger flame can be generated subsequently by the merging of the flame kernels ignited by the MCGA plasma, which develops into the resident flame. The resident flame is unable to be formed in a relatively high local equivalence ratio, and it is hard to spread to the back of the cavity along the shear layer due to the large velocity gradient with a relatively low temperature. The resident flame is formed several times by the MCGA plasma ignition, which increases the possibility of the flame spreading to the back of the cavity to form the mainstream flame. The local equivalence ratio can significantly affect the cavity ignition of the kerosene-fueled scramjet combustor.