LAMINAR BURNING VELOCITIES OF TRIFLUOROMETHANE-METHANE MIXTURES - EXPERIMENT AND NUMERICAL-SIMULATION

The laminar burning velocities of uoromethane(CHF3)-methane(CH4)-oxyge n(O-2)-diluent mixtures were determined over extensive fuel concentrat ion ranges using the counterflow flame technique. Numerical simulation was performed by employing a detailed kinetic model compiled on the b ases of the GRI-Mech for methane combustion and a recent CHF3 reaction kinetic model. Comparisons between the experimental data and numerica l results indicate that while the qualitative experimental trends are well predicted by the model, there exist significant numerical disagre ements between model and experiment. Through sensitivity and flux anal yses, we identified several rate parameters which are influential to b urning velocity predictions, and proposed reasonable adjustments to th ese parameters either based on new experimental measurements or by con sidering their associated uncertainties. The effect of CHF3 addition o n the reduction of CH4 burning velocities was also experimentally and numerically examined. By substituting the inert gas in the unburned CH 4-O-2-inert mixture with CHF3 while maintaining a constant adiabatic f lame temperature, both burning velocities and mass burning rates decre ase with an increase in CHF3 substitution, thus demonstrating positive ly the combined kinetic and transport effects of CHF3 on burning veloc ity reduction and in flame inhibition. (C) 1998 by The Combustion Inst itute.