Numerical simulation of open swirl-stabilized premixed combustion

An open swirl-stabilized turbulent premixed flame is studied numerically. This study provides a better understanding of the flame properties by simulating the flow field, combustion and heat transfer. Spaldingʹs stretch-cut-slide model is extended to determine the mixing controlled fuel burning rate. Although the flame is stabilized by swirl, the flame zone is found to be free of swirl. Simulations reveal that flame stabilization relies on flow divergence instead of re-circulation although a re-circulation zone is located downstream of the flame. Also, compared with non-reacting swirling jets, the re-circulation zone becomes wider and longer under combustion. Apart from an increase in adverse pressure gradient, the decrease in turbulent diffusion tends to increase re-circulation in the open system. The strong impingement between the swirling jet and reverse flow makes the flame planar.