IGNITION AND FLAME QUENCHING OF FLOWING HETEROGENEOUS FUEL-AIR MIXTURES

A model is described for the ignition of heterogeneous fuel-air mixtures that assumes that mixing rates and chemical kinetics are infinitely fast and that the sole criterion for successful ignition is an adequate concentration of fuel vapor in the ignition zone. From analysis of the relevant heat and mass-transfer processes involved, expressions for quenching distance and minimum ignition energy are derived that have general application to both quiescent and flowing mixtures. In the present investigation attention is focused on flowing mixtures, and minimum ignition energies are measured over wide ranges of pressure, velocity, turbulence intensity, equivalence ratio, mean drop size, and fuel volatility. The results obtained show very satisfactory agreement with corresponding predicted values, thus confirming the basic premise of the model. © 1979.