Reduced Kinetic Mechanisms in Time Dependent Numerical Simulations of Nonpremixed Flames

It is of great theoretical interest to investigate the interaction between ames and vortices as a model problem to study turbulent combustion because a eld of turbulence can be considered as an ensemble of vortices of various length and time scales. Interaction between ames and vortices governs the rate of combustion and results in di erent types of instabilites. The goal of this study is to understand the limits of applicability of progressively more accurate reduced kinetic schemes for methane-air ames using time dependent numerical simulations in a two{dimensional ow eld. Nonpremixed one{, three{ and four{step reduced kinetic methane{air ame structure and ame response to interaction between a pair of counter rotating vortices with an initially laminar unstrained ame is studied. Di erent combinations of sizes and strengths for the vortex pair are selected such that various regimes on a typical ame{vortex interaction map (Cuenot and Poinsot, [1]) are covered. From the numerical experiments, continuous burning regime for all three reduced kinetic schemes are observed. Simulations in which local extinction of the ame by the vortex pair has been observed for one{ and three{step reduced kinetic mechanisms to date. Results how that chemical kinetics plays a major role in the extinction dynamics of a methane-air ame simulated with a three-step reduced scheme. The precise mechanism by which it is quenched is currently being investigated.