A chemical kinetic investigation of laminar premixed burning characteristics for methane-hydrogen-air mixtures at elevated pressures

Abstract In this paper, three recently updated mechanisms were compared with experimental data, and FFCM 1.0 mechanism was chosen to perform chemical kinetic investigation of laminar burning velocity (LBV) for CH4/H2 mixtures. Results show that increasing hydrogen and pressure, LBV presents opposite results, which depends on the competition between promotion and inhibition effect at different hydrogen fractions and pressures. Based on growth rate of LBV, it is possible to determine three regimes for CH4/H2 mixtures at high pressures. When hydrogen fraction is less than 60%, the LBV of CH4/H2 mixtures at high pressures is not very sensitive to hydrogen, showing complex variation. Flame structure and radical concentration imply that the enhanced LBV by adding hydrogen, which is a combined result of chemical and thermal effects, is realized by improving the active radical production. Then, quantitative analysis of contribution value found that reaction OH+H2=H+H2O plays an important role in H production with increasing hydrogen fraction at high pressure. Through this work, it not only studied the interactive effect between CH4/H2 combustion system and varied conditions (such as pressure and hydrogen fraction), but also the influence mechanism was revealed in depth. All these have provided useful suggestions on fuel design for power machines.