A ROLE OF CHEMICAL KINETICS IN THE SIMULATION OF THE REACTION KERNEL OF METHANE JET DIFFUSION FLAMES

摘要

The detailed structure of the stabilizing region of an axisymmetric laminar methane jet diffusion flame has been studied numerically. Computations using a time-dependent, implicit, third-order accurate numerical scheme with buoyancy effects were performed using two different C{sub}2-chemistry models and compared with the previous results using a C{sub}1-chemistry model. The results were nearly identical for all kinetic models except that the C{sub}1-chemistry model over-predicted the methyl-radical and formaldehyde concentrations on the fuel side of the flame and that the standoff distance of the flame base from the burner rim varied. The standoff distance was sensitive to the CH{sub}3 + H + (M) → CH{sub}4 + (M) reaction. The highest reactivity spot (reaction kernel) was formed in the relatively low-temperature (< 1600 K) flame base, where the CH{sub}3 + O → CH{sub}2O + H reaction predominantly contributed to the heat release, providing a stationary ignition source to incoming reactants and thereby stabilizing the trailing diffusion flame.