Flame dynamics and stability of premixed methane/air in micro-planar quartz combustors

Abstract

The flame dynamics and stability of methane/air premixed combustion in micro-planar quartz combustors were numerically studied with detailed chemical reaction mechanism. The computed flame characteristics were quantitatively and qualitatively in good agreement with experimental phenomena. The oscillating flame was observed from the perspective of three-dimensional simulation for the first time. Parametric analysis associated with channel height and channel length was performed. Results indicated that the blowout limit was found to increase first and then decrease as increasing the channel height due to the tradeoff relationship between increased areas for heat flux and the extended timescales for energy diffusion. The change in channel length can lead to the variation in residence time of mixture in channel and heat loss from the external wall. It was found that there existed a critical point of channel length, above which the flame stability was improved marginally. Furthermore, it was shown that wall thermal conductivity had effect on both the flame structure and flame location, especially at relatively high inlet velocities. Further analyses indicated that the mechanism of enhanced flame stability with sufficient high wall thermal conductivity can be attributed to the lower strain rate and smaller deflection of streamlines in flame front.