Experimental study on smoke back-layering length and temperature distribution in bifurcation tunnels

doi:10.16265/j.cnki.issn1003-3033.2022.03.015

Abstract

Abstract:

In order to study smoke flow characteristics in case of fire in bifurcation tunnels, a series of fire experiments in the 1∶10 scale tunnel model were carried out with fire source located in bifurcation tunnels. Two heat release rates (15.9 and 31.9 kW) and 7 ventilation wind speeds (0, 0.45, 0.60, 0.75, 1.0, 1.3 and 1.6 m/s) were selected, and smoke's back-layering length, temperature distribution in the main tunnel and bifurcation tunnel under different longitudinal ventilation speeds were analyzed. The results show that when the fire source is located in bifurcation tunnels, smoke back-layering length in the main tunnel conforms to THOMAS prediction model, but coefficient C_d is much smaller than previous research results in single-hole tunnel. The dimensionless smoke temperature distribution in the main tunnel agrees with longitudinal temperature attenuation model, with coefficient k attenuating in a power function along with increase of longitudinal ventilation, and that in bifurcation tunnel corresponds with longitudinal temperature attenuation model too, but with coefficient k' demonstrating linear attenuation as longitudinal ventilation increases.

Key words: bifurcation tunnel, smoke back-layering length, temperature distribution, longitudinal ventilation, prediction model

GAO Yunji, LUO Yueyang, LI Zhisheng, ZHANG Yuchun, YU Yangyang, LI Tao. Experimental study on smoke back-layering length and temperature distribution in bifurcation tunnels[J]. China Safety Science Journal, 2022, 32(3): 109-115.

Figures/Tables 13

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Tab.1

Summary of experimental conditions

工况	火源功率/kW	通风风速/(m· $s - 1$ )
1—7	15.9	0、0.45、0.6、0.75、1.0、1.3、1.6
8—14	31.9	0、0.45、0.6、0.75、1.0、1.3、1.6

Tab.1

Fig.3

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Tab.2

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Fig.8

Fig.9

Fig.10

Tab.3

References 17

[1]	范传刚. 隧道火灾发展特性及竖井自然排烟方法研究[D]. 合肥: 中国科学技术大学, 2015.
	FAN Chuangang. Studies on characteristics of tunnel fire development and natural ventilation mode using shafts[D]. Heifei: University of Science and Technology of China, 2015.
[2]	G15沈海高速猫狸岭隧道“8.27”事故原因公布[EB/OL].[2021-09-15]. https://baijiahao.baidu.com/s?id=1654142390385221390&wfr=spider&for=pc.
[3]	宋夕雨, 阳东, 陈建忠. 多匝道隧道纵向排烟分区划分与风机匹配计算[J]. 中国安全科学学报, 2020, 30(5): 136-142. doi: 10.16265/j.cnki.issn1003-3033.2020.05.021
	SONG Xiyu, YANG Dong, CHEN Jianzhong. Longitudinal smoke exhaust zone division and fan matching calculation for multi-ramp tunnel[J]. China Safety Science Journal, 2020, 30(5): 136-142. doi: 10.16265/j.cnki.issn1003-3033.2020.05.021
[4]	李智胜, 高云骥, 李小松, 等. 分岔隧道强羽流驱动的顶棚射流火焰特征[J]. 中国安全科学学报, 2020, 30(6): 166-171. doi: 10.16265/j.cnki.issn1003-3033.2020.06.024
	LI Zhisheng, GAO Yunji, LI Xiaosong, et al. Flame characteristics of ceiling jet flow driven by strong plume in bifurcation tunnels[J]. China Safety Science Journal, 2020, 30(6): 166-171. doi: 10.16265/j.cnki.issn1003-3033.2020.06.024
[5]	陈龙飞. 纵向通风与顶棚集中排烟作用下隧道火灾顶棚射流行为特性研究[D]. 合肥: 中国科学技术大学,2016.
	CHEN Longfei. Studies on tunnel fire ceiling jet characteristic with longitudinal ventilation and ceiling smoke extraction[D]. Heifei: University of Science and Technology of China, 2016.
[6]	THOMAS P H. The movement of buoyant fluid against a stream and the venting of underground fires[J]. Fire Safety Science, 1958, 351: 1-9.
[7]	HU Longhua, HUO Ran, CHOW W K. Studies on buoyancy-driven back-layering flow in tunnel fires[J]. Experimental Thermal and Fluid Science, 2008, 32(8): 1468-1483. doi: 10.1016/j.expthermflusci.2008.03.005
[8]	LI Yingzheng, LEI Bo, INGASON H. The maximum temperature of buoyancy-driven smoke flow beneath the ceiling in tunnel fires[J]. Fire Safety Journal, 2011, 46(4): 204-210. doi: 10.1016/j.firesaf.2011.02.002
[9]	姜学鹏, 陈欣格, 郭昆. 侧部点式排烟隧道火灾临界风速研究[J]. 中国安全科学学报, 2021, 31(3):105-111. doi: 10.16265/j.cnki.issn1003-3033.2021.03.015
	JIANG Xuepeng, CHEN Xin'ge, GUO Kun. Study on critical velocity of lateral point smoke extraction tunnel fire[J]. China Safety Science Journal, 2021, 31(3):105-111. doi: 10.16265/j.cnki.issn1003-3033.2021.03.015
[10]	KURIOKA H, OKA Y, SATON H, et al. Fire properties in near field of square fire source with longitudinal ventilation in tunnels[J]. Fire Safety Journal, 2003, 38(4): 319-340. doi: 10.1016/S0379-7112(02)00089-9
[11]	TANG Fei, LI Lianjian, CHEN Wenkang, et al. Studies on ceiling maximum thermal smoke temperature and longitudinal decay in a tunnel fire with different transverse gas burner locations[J]. Applied Thermal Engineering. 2017,110:1674-1681.
[12]	马砺, 李超华, 张鹏宇, 等. 封堵比例对隧道火灾顶棚温度分布的影响[J]. 中国安全科学学报, 2020, 30(2):79-85. doi: 10.16265/j.cnki.issn1003-3033.2020.02.013
	MA Li, LI Chaohua, ZHANG Pengyu, et al. Influence of sealing ratio on ceiling temperature distribution of tunnel fire[J]. China Safety Science Journal, 2020, 30(2): 79-85. doi: 10.16265/j.cnki.issn1003-3033.2020.02.013
[13]	HUANG Youbo, LI Yanfeng, LI Junmei, et al. Experimental investigation on maximum gas temperature beneath the ceiling in a branched tunnel fire[J]. International Journal of Thermal Sciences, 2019: DOI: 10.1016/j.ijthermalsci.2019.105997.
[14]	CHEN Longfei, MAO Pengfei, ZHANG Yuchun, et al. Experimental study on smoke characteristics of bifurcated tunnel fire[J]. Tunnelling and Underground Space Technology,2020,98: DOI:10.1016/j.tust.2020.103295.
[15]	LI Zhisheng, GAO Yunji, LI Xiaosong, et al. Effects of transverse fire locations on flame length and temperature distribution in a bifurcated tunnel fire[J]. Tunnelling and Underground Space Technology, 2021, 112: DOI:10.1016/j.tust.2021.103893.
[16]	胡隆华. 隧道火灾烟气蔓延的热物理特性研究[D]. 合肥: 中国科学技术大学, 2006.
	HU Longhua. Studies on thermal physics of smoke movement in tunnel fires[D]. Heifei: University of Science and Technology of China, 2006.
[17]	FAN Chuangang, YANG Jian. Experimental study on thermal smoke backlayering length with an impinging flame under the tunnel ceiling[J]. Experimental Thermal and Fluid Science. 2017,82:262-268.

火源功率/kW	纵向风速/ (m·s^-1)	k	Adj.R-Square
15.9	0	0.644	0.945
	0.45	0.682	0.940
	0.6	0.877	0.944
	0.75	0.956	0.952
	1.0	0.921	0.943
	1.3	1.216	0.961
31.9	0	0.637	0.954
	0.45	0.719	0.956
	0.6	0.631	0.950
	0.75	0.735	0.952
	1.0	0.763	0.959
	1.3	1.292	0.952
	1.6	2.230	0.970

火源功率/kW	纵向风速/ (m·s^-1)	α	k	y₀	Adj. R-Square
15.9	〗0	0.766	2.429	0.198	0.962
	0.45	0.859	2.191	0.168	0.981
	0.6	0.855	2.099	0.162	0.984
	0.75	0.822	2.162	0.151	0.973
	1.0	0.780	1.802	0.150	0.986
	1.3	0.819	1.196	0.168	0.961
31.9	0	0.829	2.001	0.189	0.975
	0.45	0.824	1.830	0.165	0.960
	0.6	0.803	1.890	0.167	0.959
	0.75	0.789	1.877	0.170	0.956
	1.0	0.766	1.767	0.177	0.979
	1.3	0.790	1.423	0.172	0.984
	1.6	0.806	1.286	0.168	0.983