Effect of equivalence ratio on premixed flame response to unsteady strain-rate and curvature

The interaction of a premixed stoichiometric methane-air flame with a two-dimensional counter-rotating vortex pair is studied under stoichiometric and rich conditions using a detailed C{sub 1}C{sub 2} chemical mechanism. The focus is on the effect of equivalence ratio on flame response to unsteady strain-rate and curvature. Flame structure and transient response are studied, both at curved cusps and on the vortex-pair centerline. The rich flame is found to exhibit faster response to flow disturbances. Results suggest this is due to the increased sensitivity of the flame to H concentration at rich conditions. Significant differences are observed in the unsteady behavior of some C{sub 2} species, where substantial transient accumulation is observed at stoichiometric conditions, but not at rich conditions. Transient response of flame observables, such as CH, OH, and HCO, is studied and compared to experimental data