Experimental and numerical determination of laminar flame speeds: Mixtures of C₂-hydrocarbons with oxygen and nitrogen

Using the counterflow flame technique, laminar flame speeds of mixtures of ethane, ethylene, acetylene and propane with oxygen and nitrogen have been accurately determined over extensive lean-to-rich fuel concentration ranges and over the pressure range of 0.25 to 3 atm. These data are then compared with the numerically calculated values obtained by using the various kinetic schemes in the literature as well as one compiled in the present study. The present scheme yields close agrrement with all of the experimental flame speeds except for diluted, rich acetylene flames, for which the calculated values are higher. The relative importance and influence of the individual reactions on the flame speed and reaction mechanism are assessed and discussed with the aid of sensitivity analysis. The study also demonstrates that C₂ schemes validated through comparisons based on methane flame speeds may not be accurate enough for flame speed predictions of the C₂ fuels, and that the C₂ schemes developed through comparisons with the flame speeds of the C₂ fuels are rather insensitive to the details of the C₃ sub-mechanism. The importance of having accurate values of the thermophysical properties of radicals for flame simulation is also emphasized.