Effect of initial conditions on flame-vortex interactions

The effects of initial conditions on the interaction between a premixed methane-air flame and a counter-rotating vortex pair were analyzed computationally. The vortex pair propagated from the reactant side into the initially-flat front due to its own self-induced propagation velocity. This propagation resulted in large-scale deformation of the flame as it was displaced by and then wrapped around the vortex cores. When the mixture conditions in the vortex cores were identical to those of the reactants, and regardless of the initial strength of the vortex cores, of the initial core radius to separation ratio, or of the initial core temperature, a gradual decrease in peak concentrations of CH and OH was observed along the centerline. The rate of decay and its plateau were dependent on the initial vortex structure and induced velocity. In contrast, when the vortex core initially contains a leaner mixture, a qualitatively different response of the flame structure was obtained. A steep increase in peak CH and OH concentrations along the flame centerline was observed. This is an abstract of a paper presented at the 30th International Symposium on combustion (Chicago, IL 7/25-30/2004).