Smoke spreading characteristics during a fire in a shallow urban road tunnel with roof openings under a longitudinal external wind blowing |
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| Affiliation: | 1. Department of Mechanical Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;2. School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa-shi, Ishikawa 920-1192, Japan;3. Graduate School of Mechanical Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;1. Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045, PR China;2. Key Laboratory of Three Gorges Reservoir Region’s Eco-Environment, Ministry of Education, Chongqing 400045, PR China;3. National Centre for International Research of Low-carbon and Green Buildings, Chongqing 400045, PR China;1. Department of Mechanical Engineering University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;2. School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa-shi, Ishikawa 920-1192, Japan;3. Graduate School of Mechanical Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;1. Graduate School of Mechanical Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;2. School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa-shi, Ishikawa 920-1192, Japan;3. Department of Mechanical Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan;1. School of Automotive and Transportation Engineering, Hefei University of Technology, Hefei, Anhui 230009, China;2. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, China |
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| Abstract: | A series of fire experiments was conducted using a 1:12 scale model of a shallow urban road tunnel with roof openings to clarify the flow structure of smoke and fresh air during a fire with a longitudinal external wind blowing above the roof openings. The model tunnel consisted of two road tubes separated by a pillar-type median structure. Five fire test cases were conducted by changing the heat release rate as the experimental parameter. When the smoke produced by a fire in the tunnel tube was exhausted by natural ventilation through the roof openings of the tunnel tube, fresh air was sucked in from the roof openings of the opposite tunnel tube. The flow of exhausted smoke and sucked-in fresh air created a complex three-dimensional flow structure inside the tunnel tubes. Stratified smoke that had formed under the ceiling of the tunnel tube was disturbed by the flow of sucked-in fresh air and was diffused on the upstream side of the fire. Compared to the condition without a longitudinal external wind, when a longitudinal external wind blew over the tunnel with the pillar median structure, the smoke spreading distance on the upstream side was longer than that without the external wind due to the diffusion of smoke. On the other hand, the smoke spreading distance on the downstream side of the fire was shorter than that without the external wind due to the improved smoke extraction performance by the Venturi effect of the longitudinal external wind. Furthermore, the smoke spreading distance on the downstream side was nearly constant and independent of the heat release rate of the fire, within the scope of our experimental conditions. |
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| Keywords: | Longitudinal external wind Road tunnel with roof openings Natural ventilation Tunnel fire Smoke spreading distance Model experiment Median structure |
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