A Comparison between Methane and Propane Counterflow flame Acoustic Excitation in the Partially Premixed Regime

The effect of fuel type on the structure of partially premixed counterflow flame subjected to acoustic fluctuations is investigated experimentally. These features are analyzed using high-speed CH* chemiluminescence, to determine relevant flame dynamics and the flame transfer function. Flame transfer functions were found t be similar to the other simple flames, such as a premixed conical flame. The structure of partially premixed counterflow flame, especially the distance between the rich premixed reaction zone and the non-premixed reaction zone is changed by fuel type. For the propane flame, the distance between the two reaction zones is greater than the methane flame, according to more delay at the pyrolysis reactions. The flame transfer function of the propane and the methane flame showed that the decay of flame response in propane is slower than in methane; because of the slower pyrolysis reaction rates. There is a strong correlation between the area and the heat release response functions.