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Temperature distribution in a blocked tunnel with one closed portal under natural ventilation
Tunnelling and Underground Space Technology ( IF 6.9 ) Pub Date : 2020-12-30 , DOI: 10.1016/j.tust.2020.103752
Zihao Wang , Jiaqiang Han , Jun Wang , Pengqiang Geng , Miaocheng Weng , Fang Liu

A new tunnel with closed portal has been constructed in the real project, most of current research on fire smoke movement are focus on traditional tunnel with two opening portals. In this paper, 44 numerical simulation tests were conducted in a 1:10 small scale model tunnel with different sealed situations, blockages and cross-sections. More specifically, two blockage ratios, width-blockage ratio β1 and height-blockage ratio β2 were introduced. Moreover, the maximum temperature under tunnel ceiling, as well as temperature distribution in downstream direction along the tunnel centerline were especially investigated. The results indicated that: 1) The smoke accumulated and temperature increased in the tunnel caused by the closed portal. 2) The stability of smoke layer in the tunnel destroyed and the height of smoke layer interface reduced by the blockage of metro train. 3) As the width-blockage ratio β1 decreased, the vertical temperature and temperature in downstream direction decreased. Meanwhile, as the height-blockage ratio β2 decreased, the vertical temperature decreased but temperature in downstream direction increased. 4) The maximum temperature beneath tunnel ceiling was positively related to the height-blockage ratio β2, but negatively related to the width-blockage ratio β1. Based on theoretical analysis and simulation results, a revised prediction model for the maximum temperature beneath tunnel ceiling was proposed, which taking into account the blockage, tunnel cross-section and heat release rate.



中文翻译:

自然通风条件下封闭通道的封闭隧道的温度分布

实际项目中已经建造了一条带封闭门的新隧道,目前有关火灾烟雾运动的研究大多集中在具有两个开放门的传统隧道上。本文在1:10小型模型隧道中进行了44次数值模拟试验,隧道具有不同的密封情况,堵塞和横截面。更具体地,两个阻挡比,宽度-阻挡比β1个 和高度阻挡率 β2被介绍了。此外,还专门研究了隧道顶棚下的最高温度以及沿隧道中心线向下游方向的温度分布。结果表明:1)由于封闭的门洞,烟气在隧道内积聚,温度升高。2)地铁列车的堵塞,破坏了隧道内烟层的稳定性,降低了烟层界面的高度。3)作为宽度阻挡率β1个下降,垂直温度和下游方向的温度下降。同时,作为高度阻挡率β2下降,垂直温度下降,但下游方向的温度上升。4)隧道顶棚下的最高温度与高阻比呈正相关β2,但与宽度阻挡率负相关 β1个。在理论分析和模拟结果的基础上,提出了一种考虑了堵塞,隧道横截面和放热率的修正的隧道顶棚最高温度预测模型。

更新日期:2020-12-30
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