Effects of ignition disturbance on flame propagation in a narrow-gap-disk-burner

Abstract

Unsteady flame propagation in a mesoscale burner has not been clearly analyzed mainly due to complicated interactions with various characteristic length scales. We developed a new narrow-gap disk burner to observe the mesoscale flame propagation in detail. The experiment was conducted with various equivalence ratios of methane and propane and various disk-gaps. In most cases, regardless of equivalence ratios, flame propagation velocities were slower at small disk-gaps near quenching distance, faster at larger disk-gaps, and converged asymptotically to one value at much larger disk-gaps. At certain equivalence ratios, however, flame propagation velocities were faster even at disk-gaps near quenching distance. These exceptions were thought to be concerned with the flow disturbance in the process of initial ignition. However, it has not been clarified yet. Therefore, we improved the burner so that it could change its volume of the ignition part to control the initial flow disturbance. When the disk-gaps were near quenching distance, larger initial cavity volume enhanced flame velocities and cellular structures. On the contrary, when disk-gaps were much larger than quenching distance, cavity volume had little impact on flame velocities and cellular structures. Through this study, we figured out the effect of ignition disturbance on mesoscale flame propagation.