Combustion Enhancement in a Cavity-Based Scramjet Combustor by a Gliding Arc

Based on the OpenFOAM simulation platform coupled with ZDPlasKin, a physical model for the simulation of compressible-flow combustion enhancement by a nonequilibrium gliding arc plasma is developed. The characteristics of supersonic combustion with plasma in a cavity-based scramjet combustor with a Mach 2.92 flow are investigated to reveal the mechanism by which combustion is enhanced by gliding arc plasma. Among three cases enhanced by plasma at different positions, case 2, with plasma on the downstream wall of the fuel injection, shows the greatest enhancement, increasing the average wall pressure by 28% and expanding the high-temperature region by 30%. The plasma in the flow also increases fuel penetration and mixing efficiency by 12% and 33%, respectively. The plasma induces flame propagation from the cavity leading edge to the plasma area by creating a low-speed region. The reaction kinetics of plasma-enhanced combustion reveal that the deexcitation of high-order excited states, the consumption of H, and the generation of OH result in the formation of hot air bubbles and alter the flowfield in the low-speed region. [Formula: see text] and [Formula: see text] are transported into the cavity, and the corresponding reactions directly enhance the combustion.