University of California Energy Institute

Experimental and numerical studies are conducted on extinction of methanol and ethanol flames. Two flame types are considered: premixed and nonpremixed. The studies are performed in the counterflow configuration. The burner used in the experiments is made up of two opposing ducts. In the premixed configuration the reactive stream, made up of fuel, oxygen, and nitrogen, is injected from one duct, and a nitrogen stream is injected from the other duct. In the nonpremixed configuration the fuel stream is made up of fuel and nitrogen, and it is opposed by an oxidizer stream made up of air. The fuels are prevaporized by flowing nitrogen through a heated bath of liquid fuel. The velocities of the reactant streams at the injection planes are calculated from measured flowrates. These velocities are used to calculate the strain rate. The temperature of the fuel stream and that of the nitrogen stream at the injection plane are measured using thermocouples. Critical conditions of extinction are reported, giving the strain rate at extinction as a function of the mass fraction of various reactants. In the premixed configuration various equivalence ratios of the premixed stream are tested. Further experiments are conducted in the nonpremixed configuration by preheating the oxidizer stream and measuring the temperature at which autoignition occurs. Numerical calculations are performed using detailed chemistry at conditions corresponding to those used in the experiments. Critical conditions of extinction and ignition are calculated. The numerical results are compared with the experiments.