Synchronous gliding arc plasma-assisted ignition characteristics within dual-cavity in a kerosene-fueled model scramjet combustor

In response to the challenge of achieving reliable and repeatable ignition in scramjet combustors at low flight Mach numbers, this paper introduces a kerosene-air gliding arc plasma (GA fa ) igniter. Experimental investigations were conducted at a freestream total temperature of 900 K and a freestream velocity of Mach number 4, supplemented by Large Eddy Simulation (LES) to clarify the fundamental mechanisms of GA fa -enhanced ignition in supersonic flows. Experiments on dual GA fa igniter-assisted ignition under different Global Equivalence Ratios (GER) show that the GA fa igniter significantly expands ignition limits compared to conventional high-energy spark igniters. The ignition process exhibits a critical GER threshold, leading to transitions among ignition failure, upstream cavity (C 1 ) stabilization, flame blowout, and downstream cavity (C 2 ) stabilization. Numerical simulations under pure-mixing conditions reveal that at low GER, insufficient Local Equivalence Ratios (LER) and poor kerosene atomization cause failure. As GER increases, C 1 achieves suitable LER first for ignition. At high GER, combustion-induced adverse pressure in C 2 prevents strong shock train formation upstream of C 1 , while enhanced turbulence from C 1 promotes C 2 recirculation zone reactions, stabilizing the flame exclusively in C 2 .