Experimental investigation on fire smoke bifurcation flow in longitudinal ventilated tunnels

被引:14
|
作者
Zhao, Shengzhong [1 ,2 ]
Liu, Fang [2 ]
Wang, Jun [2 ]
Obadi, Imad [2 ]
Weng, Miaocheng [2 ]
Xu, Tiantian [2 ]
机构
[1] Shandong Jianzhu Univ, Sch Thermal Energy Engn, Jinan, Peoples R China
[2] Chongqing Univ, Sch Civil Engn, Chongqing, Peoples R China
基金
中国国家自然科学基金;
关键词
bifurcation flow; longitudinal ventilation; low-temperature region; tunnel fires; BACK-LAYERING LENGTH; CRITICAL VELOCITY; TEMPERATURE DISTRIBUTION; VERTICAL SHAFT; NATURAL VENTILATION; PERFORMANCE; BEHAVIORS; LOCATIONS; WIND; GAS;
D O I
10.1002/fam.2828
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Investigation of smoke bifurcation flow has been receiving more attentions, however, delicate quantitative analyses on different regions of the bifurcation flow have rarely been addressed. In this study, a series of small-scale experiments were conducted to investigate smoke bifurcation flow in longitudinal ventilated tunnels. Results show that when longitudinal ventilation velocity increases to a certain value, the smoke bifurcation phenomenon emerges, and a low-temperature region forms in the center of the tunnel. Similar to the natural conditions, smoke development under relatively strong ventilation can also be subdivided into four regions. With the increase of ventilation velocity, the ceiling impact region, side wall impact region, and convergence region of two smoke streams move further downstream, indicating that the bifurcation phenomenon becomes more evident. A simple model is proposed based on theoretical analysis and experimental phenomenon to predict two characteristic lengths of smoke bifurcation flow: the offset distance of ceiling impact region and the length of low-temperature region. Both characteristic lengths increase with ventilation velocity and can be well correlated with the dimensionless ventilation velocity defined in Equation (2) ( V-'). The results of this work could provide references for both tunnel ventilation designers and fire science researchers.
引用
收藏
页码:648 / 659
页数:12
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