Studies on non-premixed flame streets in a mesoscale channel

The effects of channel width, wall temperature, and flow rate on the dynamics of non-premix flames in a mesoscale combustor were studied in methane and propane-air mixing layers. A flame street structure which consists of multiple triple flamelets in the mixing layer of the reactants was observed experimentally for the first time. Depending on the flow rate, it was found that there are two different flame regimes, an unsteady bimodal flame regime and a flame street regime where there are multiple stable triple flamelets. It was found that the separation distance of the flamelets increased due to the dilution effect of the products and that the size of the flamelets was proportional to the width of the mixing layer. A scale analytical model was developed to qualitatively explain the mechanism of flame streets. The effects of flow velocity, wall temperature, and Lewis number were also investigated and the results showed that the occurrence of flame street regimes was a combined result of heat loss, curvature, diffusion, and dilution effect.