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首页> 外文期刊>Journal of Civil Engineering and Management >EFFECTS OF VERTICAL SHAFT GEOMETRY ON NATURAL VENTILATION IN URBAN ROAD TUNNEL FIRES
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EFFECTS OF VERTICAL SHAFT GEOMETRY ON NATURAL VENTILATION IN URBAN ROAD TUNNEL FIRES

机译：竖井几何形状对城市道路隧道火灾自然通风的影响

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摘要

A set of burning experiments were conducted to investigate the effect of vertical shaft geometry on natural ventilation in urban road tunnel fires. Results show that using vertical shafts to discharge smoke leads to a boundary layer separation near the right-angle connection of the shaft and the tunnel ceiling. In a low shaft, the turbulent-boundary-layer separation phenomenon causes relatively large-scale vortexes and restricts smoke from being exhausted, resulting in a negative effect on natural ventilation. Replacing the right-angle connection with the bevel-angle connection was proposed to split one separation point into two separation points, to attenuate the negative effect. The detailed characteristics of the separation phenomenon were analysed and the proposition was verified by Large Eddy Simulation. Results show that there are no relatively large-scale vortexes in shafts with bevel-angle connections, resulting in improved natural ventilation effectiveness. For lower shafts, the advantage of using the bevel-angle connection is more significant, and for shafts of the same height, the mass flow rate of smoke discharged by shafts with the bevel-angle connection increases up to 1.5 times of that by shafts with the right-angle connection. For relatively high shafts, it is about 1.2 times.
机译：进行了一组燃烧实验，以研究竖井几何形状对城市道路隧道火灾中自然通风的影响。结果表明，使用竖井排放烟气会导致竖井与隧道顶板直角连接附近的边界层分离。在低井筒中，湍流边界层分离现象会引起较大规模的涡旋并限制烟气排出，从而对自然通风产生负面影响。提出用斜角连接代替直角连接，以将一个分离点分成两个分离点，以减轻负面影响。分析了分离现象的详细特征，并通过大涡模拟验证了该命题。结果表明，斜角连接的轴中没有相对较大的涡旋，从而提高了自然通风效率。对于下部轴，使用斜角连接的优势更加明显；对于相同高度的轴，带斜角连接的轴排出的烟气质量流量增加到具有斜角连接的轴的1.5倍。直角连接。对于相对较高的轴，约为1.2倍。

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