IGNITION, BURNING AND EXTINCTION OF A STRAINED FUEL STRIP WITH COMPLEX KINETICS

Flame structure and ignition and extinction processes associated with a strained fuel strip are explored numerically using detailed transpor t and complex kinetics for a propane-air reaction. Ignition modes are identified that are similar to those predicted by one-step activation energy asymptotics, i.e., modes in which diffusion dames can ignite as independent or dependent interfaces and modes in which single premixe d or partially premixed flames ignite and burn. These ignition modes h ave been found to be dependent on critical combinations of strain rate , fuel strip thickness and initial reactant temperatures. The formatio n of NO/NO2 is found to be strongly dependent on strain rate and the l ocal molecular mixing of reactants which occurs as a consequence of st rain. Extinction in this configuration is seen to occur due to fuel co nsumption by adjacent flames, although viscosity is seen to have the e ffect of delaying extinction by reducing the effective strain rate exp erienced by the flames. Response of the flames to oscillatory strain r ates is seen to be strongly dependent on the amplitude and frequency o f the oscillation.