Study on temperature field beneath tunnel ceiling induced by transverse symmetrical double fires

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences Pub Date : 2024-06-29 DOI:10.1016/j.ijthermalsci.2024.109239

Jian Yang , Jihong Ye

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引用次数: 0

Abstract

During a tunnel fire incident, a substantial volume of high-temperature smoke gathers and disperses beneath the tunnel ceiling, posing significant risks of casualties and structural harm. A comprehensive comprehension of the temperature distribution of smoke beneath the ceiling is pivotal for the fire-resistant design and formulation of rescue plans for tunnel structures. This paper initially employs the FTP theory to analyze the fire scene resulting from fire spread under vehicle congestion. Subsequently, A set of numerical simulations is performed, and a prediction model of the temperature field for transverse symmetrical double fires is established according to the simulation results. Finally, an air entrainment model for transverse symmetrical double fires is proposed. The air entrainment amount under different fire spacing is obtained by theoretical derivation. Combined with the relationship between air entrainment amount, flame height, and maximum temperature, the variation of temperature field under the ceiling with fire spacing is explained from the mechanism. The results show that: the maximum temperature beneath tunnel ceiling increases with the increase of the fire power, decreases and then increases with the increase of the fire spacing and the variation has symmetry; The temperature attenuation along transverse and longitudinal directions under the ceiling following the exponential attenuation model, and the temperature attenuation rate is positively correlated with the maximum temperature. The transverse temperature attenuation is smaller than that of the longitudinal temperature under the same conditions; There is an internal relationship between the air entrainment, flame height and temperature field of the transverse double fires. The variation law of the temperature field beneath the ceiling depends on the degree of air entrainment limitation. Based on mirror model, this paper indicates that when the fire spacing is within a certain range, the combustion of the double fires can be effectively represented as near-wall fire.

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横向对称双火引发的隧道顶棚下温度场研究

在隧道火灾事故中，大量高温烟雾在隧道顶棚下方聚集和扩散，造成重大人员伤亡和结构损坏风险。全面了解顶棚下烟雾的温度分布，对于隧道结构的耐火设计和救援方案的制定至关重要。本文首先运用 FTP 理论分析了车辆拥堵情况下火势蔓延导致的火灾现场。随后，进行了一组数值模拟，并根据模拟结果建立了横向对称双层火灾的温度场预测模型。最后，提出了横向对称双火的空气夹带模型。通过理论推导得出了不同火距下的空气夹带量。结合空气夹带量、火焰高度和最高温度之间的关系，从机理上解释了顶棚下温度场随火距的变化。结果表明：隧道顶板下的最高温度随火力增大而升高，随防火间距增大而降低再升高，且变化具有对称性；顶板下温度沿横向和纵向的衰减遵循指数衰减模型，且温度衰减率与最高温度呈正相关。在相同条件下，横向温度衰减小于纵向温度衰减；横向双火的空气夹带量、火焰高度和温度场之间存在内在联系。顶棚下温度场的变化规律取决于空气夹带的限制程度。基于镜像模型，本文指出，当火间距在一定范围内时，双火的燃烧可有效地表示为近壁火。

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.