Structure and stabilization mechanism of a microjet methane diffusion flame near extinction

The flame structure and stabilization mechanism of a microjet methane diffusion flame near extinction are numerically investigated using multi-component transport model coupled with GRI-Mech 3.0 chemical kinetic mechanisms. The small flame size and intensive heat loss to the burner wall suggest that the microjet flame may always operate in a severe condition near extinction with distinct stabilization feature. Of particular interest is the flame structure in the standoff region, as it would directly relate to the mixing, diffusion, and chemical kinetic processes as well as flame stabilization. Computed results show that near extinction the fuel burns in a diffusion flame, in contradiction to a simple jet flame prediction. Neither a double flame nor a triple flame is observed in the computed structures, suggesting that the standoff flame is stabilized by the hot zone that connects to the reaction kernel, through the formation of HO2 layer and subsequent key radical reactions.