期刊
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
卷 46, 期 2, 页码 2658-2666出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijhydene.2020.10.024
关键词
Micro-combustor; Non-premixed combustion; Slotted bluff-body; Blow-off limit; Recirculation zone; Stretch effect
资金
- National Natural Science Foundation of China [51576084]
Researchers developed a planar micro-combustor with a slotted bluff-body for non-premixed H-2/air combustion and found that a medium blockage ratio of the bluff-body can provide a trade-off between positive and negative impacts on flame blow-off, leading to the largest blow-off limit.
A planar micro-combustor with a slotted bluff-body was developed for non-premixed H-2/air combustion. Numerical simulation was conducted and the flame blow-off limit under blockage ratio of xi = 0.45, 0.55 and 0.64 was obtained (corresponding half height of the bluff-body is 0.25, 0.30 and 0.35 mm, total height of the channel is 1.1 mm). It was found that the blow-off limit peaks at xi = 0.55. The simulation results of flame blow-off dynamics demonstrate that when the blockage ratio is small, the flame root cannot be anchored by the recirculation zone and the flame is entirely blown off the bluff-body. However, if the blockage ratio is relatively large, flame splitting occurs due to excess strain rate before flame being blown out. Analysis reveals that increasing the blockage ratio of the bluff-body has both positive and negative impacts. On the one hand, a large blockage ratio can increase the turbulence kinetic energy in the recirculation zone, which promotes fuel-air mixing and flame stability. On the other hand, the augmented stretch effect leads to local extinction and flame splitting. As a result, the combustor with a medium blockage ratio of the bluff-body can gain a tradeoff between the positive and negative aspects and achieve a largest blow-off limit. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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