Reduced Kinetic Mechanisms in Time Dependent Numerical Simulations of Nonpremixed Flames

摘要

It is of great theoretical interest to investigate the interaction between rames and vortices asrna model problem to study turbulent combustion because a feld of turbulence can be considered asrnan ensemble of vortices of various length and time scales. Interaction between rames and vorticesrngoverns the rate of combustion and results in diu000berent types of instabilites. The goal of thisrnstudy is to understand the limits of applicability of progressively more accurate reduced kineticrnschemes for methane-air rames using time dependent numerical simulations in a two{dimensionalrnrow feld. Nonpremixed one{, three{ and four{step reduced kinetic methane{air rame structurernand rame response to interaction between a pair of counter rotating vortices with an initiallyrnlaminar unstrained rame is studied. Diu000berent combinations of sizes and strengths for the vortexrnpair are selected such that various regimes on a typical rame{vortex interaction map (Cuenot andrnPoinsot, [1]) are covered. From the numerical experiments, continuous burning regime for all threernreduced kinetic schemes are observed. Simulations in which local extinction of the rame by thernvortex pair has been observed for one- and three-step reduced kinetic mechanisms to date. Resultsrnhow that chemical kinetics plays a major role in the extinction dynamics of a methane-air ramernsimulated with a three-step reduced scheme. The precise mechanism by which it is quenched isrncurrently being investigated.