海拔高度对公路隧道火灾烟气分布特性影响研究

高海拔地区存在大气压力低、空气密度小、含氧量低等特点,对公路隧道火灾燃烧和烟气扩散的影响与平原地区隧道有显著差异。为了得到不同海拔高度条件下公路隧道内火灾烟气扩散特性和温度场分布规律,依托米拉山高海拔特长隧道,采用FDS计算软件,对海拔0~ 6 km范围内不同海拔高度的隧道火灾进行三维数值模拟计算。分析不同海拔高度条件下火灾烟气逆流长度、隧道拱顶温度、距地面1.8 m高度处温度分布、隧道竖向温度分布等主要参数。研究结果表明:随着海拔高度的增加,火源上游区域烟气逆流长度不断减小,烟气逆流长度与海拔高度大致呈线性关系,海拔6 km情况下烟气逆流长度为平原地区的57%;与平原地区隧道相比,高海拔地区隧道火源上游区域温度较低,火源下游区域温度较高,高海拔隧道火源下游区域烟气温度降低幅度较大;火源下游区域,高海拔地区隧道竖向温度增长较快。

Research on the Influence of Altitude on the Distribution Characteristics of Fire Smoke in Highway Tunnels

Low atmospheric pressure, low air density, and low oxygen content are the main characteristics of high altitude areas. The influence on the fire combustion and smoke diffusion of highway tunnels is significantly different from that of plain areas. In order to obtain the fire smoke diffusion characteristics and temperature field distribution regularity in highway tunnels at different altitudes, three-dimensional numerical simulation calculation were carried out with the calculation software of FDS. Relying on the Mila mountain tunnel, which is a super-long tunnel at high altitude, tunnel fires at different altitudes within the range of 0-6 km above sea level were conducted. The main parameters such as the reversed flow length of fire smoke, the temperature at the top of the tunnel, the temperature distribution at the height of 1.8 m from the ground, and the vertical temperature distribution of the tunnel were analyzed at different altitudes. The results show that the reversed flow length of smoke in the upstream area of the fire source decreases with the altitude increased, which is approximately linear relationship. At the altitude of 6 km, the reversed flow length of smoke is 57% of the tunnel in the plain. Compared with the tunnel in the plain area, the temperature in the upstream area of the fire source at the high altitude area is lower, which is higher in the downstream of the fire source. The temperature in the downstream area of the fire source decreases significantly at the high altitude tunnel. In the downstream area of the fire source, the vertical temperature of the tunnel increases more rapidly at the high altitude.