Flame extension characteristics and the temperature profile below the tunnel ceiling with various source-ceiling heights

IF 6.7 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Xiepeng Sun , Fei Ren , Yong Yang , Yu Han , Xiang Fang
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Abstract

Flame behavior of impinging on ceiling and spreading are fundamental phenomenon in tunnel fire accidents, it involves fundamental scientific issues such as heat and mass transfer, flow, and combustion (fire). The flame boundary extension along the tunnel ceiling is a crucial parameter of ceiling jet, directly impacting temperatures, heat fluxes, and heat radiations below the tunnel ceiling. Currently, there is no systematic analysis of the evolution of ceiling flame extension behavior and temperature profile during fire growth for various source-ceiling heights. In this paper, the impinging flame extension behavior and its evolution with heat release rate below the tunnel ceiling was explored by using the computational fluid dynamics (CFD) simulation. A series of simulation tests were conducted, varying burner dimensions, source-ceiling heights, and heat release rates. The results show that, for a given source-ceiling height, a larger fire heat release rate results in a more extensive flame spread. For a given lower fire heat release rate, the flame extension length or higher temperature profile decreases with an increase in source-ceiling height. Notably, for higher fire heat release rates, the flame extension length remains relatively constant regardless of the source-ceiling height. A non-dimensional overall function has been developed to describe the evolution of ceiling flame extension length during fire growth, that takes into account both tunnel width and source-ceiling height. These novel findings, along with the proposed model provide an important basis for understanding tunnel fires.

Abstract Image

不同火源-天花板高度下的火焰延伸特性和隧道天花板下方的温度曲线
火焰撞击顶板和蔓延是隧道火灾事故中的基本现象,它涉及到传热传质、流动和燃烧(火)等基本科学问题。火焰边界沿隧道顶板的延伸是顶板射流的一个重要参数,它直接影响隧道顶板下的温度、热流密度和热辐射。目前,还没有系统的分析不同源顶高度下火焰生长过程中火焰扩展行为和温度分布的演变。本文采用计算流体力学(CFD)模拟方法,研究了隧道顶板下冲击火焰扩展行为及其随放热速率的演化规律。进行了一系列模拟测试,改变燃烧器尺寸,源天花板高度和热释放率。结果表明,在源顶高度一定的情况下,火灾热释放率越大,火焰蔓延范围越广。对于给定的较低的火焰热释放率,火焰延伸长度或较高的温度分布随着源顶高度的增加而减小。值得注意的是,对于较高的火焰热释放率,无论源顶高度如何,火焰延伸长度保持相对恒定。建立了一个考虑隧道宽度和源顶高度的无因次总体函数来描述火焰生长过程中顶棚火焰延伸长度的演变。这些新发现以及提出的模型为理解隧道火灾提供了重要的基础。
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
Tunnelling and Underground Space Technology
Tunnelling and Underground Space Technology 工程技术-工程:土木
CiteScore
11.90
自引率
18.80%
发文量
454
审稿时长
10.8 months
期刊介绍: Tunnelling and Underground Space Technology is an international journal which publishes authoritative articles encompassing the development of innovative uses of underground space and the results of high quality research into improved, more cost-effective techniques for the planning, geo-investigation, design, construction, operation and maintenance of underground and earth-sheltered structures. The journal provides an effective vehicle for the improved worldwide exchange of information on developments in underground technology - and the experience gained from its use - and is strongly committed to publishing papers on the interdisciplinary aspects of creating, planning, and regulating underground space.
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