基于FDS半敞开式城市隧道火灾数值模拟研究

发布时间：2018-01-20 20:29

本文关键词： 模拟研究半敞开式隧道隧道火灾温度场烟气逆流层　出处：《安徽理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,随着我国社会的进步和交通运输事业的迅速发展,各种城市隧道迅速涌现。隧道给人们的日常生活和交通出行带来了很多方便,也带来了一系列消防安全问题。由于隧道空间密闭且狭长,隧道内一旦发生火灾,可燃物燃烧产生的大量高温有毒有害气体在有限空间内迅速蔓延,通常会造成多数人员伤亡的重大安全事故。隧道内发生火灾时,人员一般会逆着风流逃生且消防救援人员通常会从火源上游下行,执行灭火救援工作。因此,研究隧道火灾火源上游温度场分布规律及烟气逆流特性对隧道火灾灭火救援工作具有一定的理论指导意义。本文在前人现场试验研究的基础上,利用数值模拟的方法以不同的网格尺寸对原工况进行模拟,将模拟结果与试验结果对比分析,确定了合理的网格尺寸并验证了数值模拟方法的可行性。然后,通过改变原工况中火源位置及高度参数,并对不同火源位置及火源高度工况条件进行模拟,最后,对不同工况条件下半敞开式隧道火灾火源上游顶棚温度场分布规律及烟气逆流特性进行对比分析。总结得出：第一,火源上游顶棚处温度分布沿纵向呈衰减趋势且火源越高温度衰减速度越快,贴壁火源上游顶棚温度沿纵向衰减速度大于中央火源。中央火源上游顶棚处温度横向分布由中间向两侧逐渐降低且火源面越高温度衰减梯度越大,但在离火源纵向近距离范围内出现相反的分布规律。在离火源纵向水平垂直近距离范围内,贴壁火源顶棚处温度在横向上呈倾斜和反向倾斜分布；在半敞开口段范围内,火源上游顶棚温度出现小范围的波动。第二,中央火源上方烟气逆流层的长度大于贴壁火源,火源高度增加烟气逆流层长度减小且中央火源上游烟气层高度低于贴壁火源。第三,在不同火源位置条件下,中央火源顶棚温度呈现倒立浴盆区和低温区的范围大于贴壁火源,中央火源上游烟气逆流层过渡区的范围小于贴壁火源,而稳定区和极不稳定区范围大于贴壁火源。在不同火源高度条件下,火源高度增加顶棚温度呈现凸型区、倒立浴盆区及低温区范围不断缩小,而凹形区随之扩大,同时烟气层过渡区和极不稳定区范围扩大,稳定区范围随之缩小。以上结论为隧道火灾消防安全设计提供了一定的理论依据。
[Abstract]:In recent years, with the progress of our society and the rapid development of transportation, a variety of urban tunnels have emerged rapidly. Tunnels have brought a lot of convenience to people's daily life and transportation. It also brings a series of fire safety problems. Because the tunnel space is closed and narrow, once there is a fire in the tunnel, a large number of high temperature toxic and harmful gases produced by combustible combustion spread rapidly in the limited space. When there is a fire in the tunnel, the personnel usually escape from the wind flow and the fire rescue personnel usually go down from the upstream of the fire source to carry out the fire fighting and rescue work. The research on the distribution of temperature field in the upper reaches of tunnel fire source and the characteristics of flue gas countercurrent have certain theoretical guiding significance for tunnel fire extinguishing and rescue work. In this paper, based on the previous field experiments, the numerical simulation method is used to simulate the original working conditions with different mesh sizes, and the simulation results are compared with the experimental results. The reasonable mesh size is determined and the feasibility of the numerical simulation method is verified. Then, by changing the location and height parameters of the fire source in the original working condition, the different fire source location and the working conditions of the fire source height are simulated. Finally, the temperature field distribution and smoke countercurrent characteristics in the upper reaches of the fire source of semi-open tunnel fire are compared and analyzed under different working conditions. The conclusions are as follows: first, the temperature distribution of the roof in the upstream of the fire source is attenuated along the longitudinal direction and the higher the fire source is, the faster the temperature attenuation rate is. The vertical attenuation rate of the roof temperature in the upstream of the central fire source is higher than that of the central fire source. The transverse temperature distribution of the roof in the upper reaches of the central fire source gradually decreases from the middle to the two sides and the higher the temperature attenuation gradient is the greater the temperature attenuation gradient is. In the vertical vertical and close range from the fire source, the temperature at the roof of the wall fire source is tilted laterally and tilted in the opposite direction. In the range of semi-open mouth, there is a small fluctuation of ceiling temperature in the upper reaches of the fire source. Second, the length of flue gas countercurrent layer above the central fire source is larger than that of the adherent fire source. The length of flue gas countercurrent layer decreases with the increase of fire source height and the height of upstream flue gas layer of central fire source is lower than that of wall fire source. Thirdly, under different fire source location conditions. The ceiling temperature of the central fire source is larger than that of the adherent fire source in the inverted bath area and the low temperature zone, and the range of the upstream flue gas countercurrent layer transition area is smaller than that of the adherent fire source. The range of stable and extremely unstable region is larger than that of adherent fire source. Under the condition of different fire source height, the roof temperature of fire source height increases in convex region, and the area of inverted bathtub and low temperature area is continuously reduced. The concave zone is enlarged, and the range of transition zone and extremely unstable zone of flue gas layer is enlarged, and the range of stable zone is reduced. The above conclusion provides a certain theoretical basis for the fire safety design of tunnel fire.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U458

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