Abstract
With lift flames in a diffusion combustor, there is partially premixed combustion at the base of the flame, and the flames have various flame characteristics, such as extinction and re-ignition phenomena. Elucidating those combustion mechanisms is also useful and interesting from the standpoint of discussing flame stability. In this research, we have examined the characteristics of lift flames observed in a bluff body combustor, and the effects which the behavior of annular air flow have on these flame characteristics. The results showed that there is a hysteresis phenomenon whereby the flame configuration varies under the same conditions during an increase and decrease of the fuel flow velocity. It was found that the range where this phenomenon occurs varies greatly depending on the flow velocity of the annular air. In addition, when the flow velocity of the fuel was fixed and the flow velocity of annular air was changed, the bifurcation phenomenon in the flame form was observed.
