The Extinction of Counterflow Premixed Flames Burning Diluted Methane-Air, and Diluted Propane-Air Mixtures

Abstract–A theoretical and experimental investigation of the mechanisms of extinction of counterflow premixed flames burning methane and propane is outlined. Premixed flames were stabilized between counterflowing streams of a fuel-lean, premixed mixture of fuel, air, and nitrogen and that of pure nitrogen. The composition of the combustible mixture at extinction as a function of the strain rate were measured over a wide parametric range. The experimental results were interpreted by use of asymptotic theories developed previously. Overall chemical kinetic rate parameters characterizing the gas phase oxidation of methane and propane were deduced. The limiting fuel concentration below which a premixed flame cannot be stabilized was measured. The limiting fuel concentration was found to agree well with previous measurements of flammability limits for these fuels.