Experimental investigation on maximum ceiling temperature and longitudinal attenuation in a closed tunnel with an inclined shaft

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL International Journal of Thermal Sciences Pub Date : 2024-10-14 DOI:10.1016/j.ijthermalsci.2024.109484

Mingxuan Qiu , Lin Xu , Yinghao Zhao , Chao Ding , Shengzhong Zhao , Wei Yu , Longyue Li , Xiaoxuan Zhou

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Abstract

For tunnel fires with open and closed tunnel ends, the smoke flow pattern and air supply conditions vary considerably, resulting in different maximum excess ceiling temperature (ΔT_max) and its longitudinal distribution (ΔT_x). However, few studies have focused on the tunnel closed at both ends with an inclined shaft (typical tunnel structure during construction). Hence, tunnel model 1 (tunnel closed at both ends with an inclined shaft) and tunnel model 2 (tunnel open at both ends) are built for comparison and analysis. The results show that tunnel model 1 has higher ceiling temperatures and slower attenuation than tunnel model 2. Therefore, the ΔT_x in tunnel model 1 needs to be re-analyzed in detail. Different inclined shaft slopes, fire heat release rates, longitudinal and vertical fire positions are considered. In tunnel model 1, for h (lifting height of burner surface) = 0, the ΔT_max value tends to be constant for the same heat release rate, irrespective of the longitudinal fire position. For h = 5 cm, the ΔT_max value takes on a rising trend with the fire moving downstream. Moreover, the inclined shaft slope within this study has little influence on ΔT_x. As the fire moves downstream, the downstream ΔT_x/ΔT_max value decreases more rapidly. From h = 0 to h = 5 cm, the value of ΔT_x/ΔT_max drops slightly faster, but the gap is small and can be ignored. Finally, the experimental correlations are proposed to estimate the longitudinal ceiling temperature distribution in a closed tunnel with an inclined shaft.

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带倾斜轴的封闭式隧道内最高顶温和纵向衰减的实验研究

对于两端开口和封闭的隧道火灾，烟气流动模式和供气条件有很大不同，从而导致隧道顶棚最高超温（ΔTmax）及其纵向分布（ΔTx）不同。然而，很少有研究关注两端封闭的斜井隧道（施工期间的典型隧道结构）。因此，我们建立了隧道模型 1（两端封闭的斜井隧道）和隧道模型 2（两端开放的隧道）进行比较和分析。结果表明，与隧道模型 2 相比，隧道模型 1 的顶棚温度更高，衰减更慢。因此，需要对隧道模型 1 中的ΔTx 重新进行详细分析。我们考虑了不同的斜井坡度、火灾热释放率、纵向和垂直火灾位置。在隧道模型 1 中，当 h（燃烧器表面提升高度）= 0 时，无论纵向点火位置如何，在相同的热释放率下，ΔTmax 值趋于恒定。当 h = 5 cm 时，ΔTmax 值会随着火焰向下游移动而呈上升趋势。此外，本研究中的斜井坡度对 ΔTx 的影响很小。随着火势向下游移动，下游 ΔTx/ΔTmax 值下降得更快。从 h = 0 到 h = 5 cm，ΔTx/ΔTmax 值的下降速度稍快，但差距很小，可以忽略。最后，提出了实验相关性，以估算带倾斜轴的封闭隧道中的纵向顶棚温度分布。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Thermal Sciences 工程技术-工程：机械

CiteScore

8.10

自引率

11.10%

发文量

531

审稿时长

55 days

期刊介绍： The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review. The fundamental subjects considered within the scope of the journal are: * Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow * Forced, natural or mixed convection in reactive or non-reactive media * Single or multi–phase fluid flow with or without phase change * Near–and far–field radiative heat transfer * Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...) * Multiscale modelling The applied research topics include: * Heat exchangers, heat pipes, cooling processes * Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries) * Nano–and micro–technology for energy, space, biosystems and devices * Heat transport analysis in advanced systems * Impact of energy–related processes on environment, and emerging energy systems The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.