Formation of dynamic spatial flame structures for gas burning in microchannels with temperature gradients on walls

Abstract

The thermal-diffusive model was applied to the problem of flame propagation in a microchannel with controlled temperature distribution in the walls; this demonstrated the possibility of formation of oscillating or rotating spatial flame structures, which were described previously in experimental works on microcombustion. Two cases were considered: combustion in a rectangular channel and in the clearance between two disks with radial feeding of premixture. In both cases, the typical across size of the channel was lower than the critical diameter determined with respect to the ambient temperature. The gas flow was assigned and described by the Poiseuille-flow velocity profile. Formation of oscillating flame in a rectangular channel and rotating patterns in a radial channel was observed for a certain range of gas flow rate. At low flow rates beyond this range, repetitive ignition/extinction of flame took place; at high flow rate we observed a steady flame mode. Formation of these special flame structures is related to heat transfer between gas and hot walls of the channel, as well as to velocity maldistribution in the microchannel.