Premixed flame propagation in a high-intensity, large-scale vortical flow

Abstract

The propagation of a premixed flame through a large-scale vortical flow field is studied numerically by solving a front propagation equation governing the evolution of a scalar field whose zero-level surface defines the location of a self-propagating interface. The flame front is considered to propagate normal to itself with a constant speed, and the density variation across the flame is considered to be zero. Average burning rates are calculated for large velocity fluctuation intensities, as the formulation allows naturally for the formation of pockets of unburned gas downstream from the reaction front. The propagation rate of the corrugated flame front is found to vary periodically with time, with an average that varies linearly with velocity fluctuation intensity at large intensities. A mechanism is identified for the decreasing sensitivity of the average burning rate to increases in the fluctuation intensity, over an intermediate range of intensities, in the zero-viscosity limit.