Confinement Effects on Coaxial Jet Diffusion Flame

doi:10.1080/00102202.2023.2277785

	Confinement Effects on Coaxial Jet Diffusion Flame
	Wang XZ(王秀珍); Zhu F(朱凤); Wang SF(王双峰); Wang, Zhengyang
刊名	COMBUSTION SCIENCE AND TECHNOLOGY
	2023-11-09
页码	29
关键词	Diffusion flame confinement ratio velocity flame characteristics recirculation
ISSN号	0010-2202
DOI	10.1080/00102202.2023.2277785
通讯作者	Zhu, Feng(zhufeng@imech.ac.cn)
英文摘要	A combined experimental and numerical study has been conducted to investigate the characteristics of confined coaxial jet diffusion flames in air coflow, using methane as fuel. The main concerns were focused on the unequal fuel velocity (0.1-72 m/s)/air velocities (0.045-0.53 m/s) and confinement ratio (delta, defined as the ratio of the confinement tube diameter and the jet diameter), and most of the flow remains laminar while the ranges of delta and gas velocities vary widely. The flame height linearly increases with the central fuel jet velocity, until the flame tip-opening or liftoff occurs, which is similar to that of the free jet flame. The critical fuel jet velocity for flame liftoff decreases with the ratio of air velocities to delta * . The critical fuel jet velocity of flame tip-opening increases with delta, and the critical volumetric flow rate of air increases to a maximum, then decreases, indicating a combined effect of the oxygen supplement and the mixing with the fuel. Under smaller delta with high jet flow velocity, a circular plane flame is observed before flame extinction. The formation of a recirculation zone in a confinement with combustion reaction has a significant influence on flame behaviors. A critical nondimensional Craya-Curtet number is used to predict the onset of flow recirculation with combustion reaction. At a certain coflow air velocity, the critical number initially increases and then remains constant with delta, while at a certain delta, the critical number decreases with air velocity. When the Craya-Curtet number is higher than the critical point, recirculation cannot be established, resulting in the formation of a tip-closed flame. With the decrease of the Craya-Curter number, the recirculation evolves to the upstream of the flame, then, the flame may be lifted off, along with the recirculation zone moving downstream. With the effect of recirculation, the stoichiometric mixture fraction contour shrinks toward the central axis where there is a higher local velocity. Therefore, the flame will be lifted off under a lower jet velocity in a smaller delta * . With the increase of the jet velocity, the Craya-Curtet number further decreases, and the recirculation becomes much stronger than the upstream inflow, resulting in the flame being compressed into a circular plane flame at a small delta* with a relatively high jet flow velocity or blowout directly at a relatively large delta * .
分类号	Q3
资助项目	This work is supported by the National Key Ramp;D Program of China under Grant No. 2021YFA0716202, the Space Application System of China Manned Space Program, and the Young Elite Scientists Sponsorship Program by BAST under Grant No. BYESS2023440.[2021YFA0716202] ; National Key Ramp;D Program of China ; Space Application System of China Manned Space Program[BYESS2023440] ; Young Elite Scientists Sponsorship Program by BAST
WOS关键词	COMBUSTION CHARACTERISTICS ; INVERSE ; STABILITY ; METHANE ; RECIRCULATION ; BURNER ; TEMPERATURE ; GENERATION ; PREDICTION ; SIZES
WOS研究方向	Thermodynamics ; Energy & Fuels ; Engineering
语种	英语
WOS记录号	WOS:001099335300001
资助机构	This work is supported by the National Key Ramp;D Program of China under Grant No. 2021YFA0716202, the Space Application System of China Manned Space Program, and the Young Elite Scientists Sponsorship Program by BAST under Grant No. BYESS2023440. ; National Key Ramp;D Program of China ; Space Application System of China Manned Space Program ; Young Elite Scientists Sponsorship Program by BAST
其他责任者	Zhu, Feng
内容类型	期刊论文
源URL	[http://dspace.imech.ac.cn/handle/311007/93355]
专题	力学研究所_国家微重力实验室
推荐引用方式 GB/T 7714	Wang XZ,Zhu F,Wang SF,et al. Confinement Effects on Coaxial Jet Diffusion Flame[J]. COMBUSTION SCIENCE AND TECHNOLOGY,2023:29.
APA	王秀珍,朱凤,王双峰,&Wang, Zhengyang.(2023).Confinement Effects on Coaxial Jet Diffusion Flame.COMBUSTION SCIENCE AND TECHNOLOGY,29.
MLA	王秀珍,et al."Confinement Effects on Coaxial Jet Diffusion Flame".COMBUSTION SCIENCE AND TECHNOLOGY (2023):29.