| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1730733 | Energy | 2016 | 11 Pages |
•Flame blow-off limit in a mesoscale bluff-body combustor is experimentally obtained.•Interplays between flame and transport processes are responsible for flame stability.•Recirculation zone provides a region to achieve velocity balance for flame anchoring.•Preferential transport increases local equivalence ratio that favors flame stability.•Excessively large strain rate is the reason for the occurrence of flame blow-off.
It is challenging to maintain a stable flame in miniature combustors. In the present work, a mesoscale bluff-body combustor was developed. The flame blow-off limits of CH4/air mixtures were experimentally obtained, which showed that the bluff body can effectively expand the flame stabilization limit. The flame anchoring mechanisms of this mesoscale bluff-body combustor were studied through 3D numerical simulation. It is revealed that a flow recirculation zone is formed behind the bluff body and its area increases with the increase of inlet velocity. Moreover, the incoming fresh mixture can be preheated by both the upstream channel wall and the front and side walls of the bluff body, which leads to an earlier initiation of chemical reactions. Furthermore, the local equivalence ratio grows larger than that of the incoming pre-mixture due to preferential transport effect, which favors the flame stabilization, especially for relatively leaner mixtures. Besides, the dynamic process of flame blow-off was numerically reproduced, which demonstrates that the excessively large strain rate is responsible for flame extinguishment at high inlet velocity. In conclusion, the present work revealed the complex interactions between flow field, mass and heat transfer processes, and chemical reactions in the mesoscale bluff-body combustor.
