Understanding smoke temperature distributions and transport characteristics is of great importance to control and exhaust thermal‐driven smoke. However, previous studies have focused on this problem in plain areas, whereas ambient pressure decreases as elevation increases. This study investigates the influence of ambient pressure on the hot gas temperature distribution and movement characteristics in a tunnel fire. A series of numerical simulations are carried out in a vehicle tunnel with various heat release rates (HRRs) and ambient pressures. The results show that the maximum temperature and longitudinal temperature distribution under the tunnel ceiling increase with decreasing ambient pressure due to less heat loss caused by lower air density. In addition, the vertical temperatures of the smoke are slightly higher under lower ambient pressure, and this phenomenon makes the smoke spread slightly faster while the smoke layer thickness remains nearly the same under different ambient pressures. The results can provide a reference for tunnel lining design and ventilation arrangements in high‐altitude areas.

中文翻译：

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高海拔地区隧道火灾中烟雾运动特性的研究

了解烟雾温度分布和传输特性对于控制和排放热驱动烟雾非常重要。然而，先前的研究集中在平原地区的这个问题上，而环境压力随着海拔的升高而降低。这项研究调查了环境压力对隧道火灾中热气温度分布和运动特性的影响。在具有不同排热率（HRR）和环境压力的车辆隧道中进行了一系列数值模拟。结果表明，隧道顶棚下的最高温度和纵向温度分布随着环境压力的降低而增加，这是由于较低的空气密度导致的热损失较少。此外，在较低的环境压力下，烟雾的垂直温度会略高，在不同的环境压力下，这种现象使烟雾散布的速度略快，而烟雾层的厚度几乎保持不变。研究结果可为高海拔地区隧道衬砌设计和通风布置提供参考。