火源功率与隧道阻塞比对临界风速变化规律影响研究

Study on influence law of fire power and blockage ratio on critical wind velocity in tunnel fire

临界风速是隧道进行通风排烟设计的重要参数,为了研究火源功率、隧道阻塞比对临界风速变化规律的影响,采用Pyro Sim火灾动力学模拟工具与经验公式对比分析的方式。建立隧道缩尺寸模型,并对模型网格尺寸划分进行可靠性校验,发现网格尺寸为火源特征直径的十分之一时最可靠。结果表明:模拟临界风速与理论临界风速相吻合,临界风速随火源功率的增加而增大,当火源功率大于某范围时,临界风速开始趋于稳定;临界风速受到列车对隧道阻塞作用的影响,临界风速随着隧道横截面阻塞比的增加而呈线性减小,在阻塞比达到40%时,临界风速趋于稳定。

The critical wind velocity is an important parameter for design of tunnel ventilation and smoke exhaust. In order to research the influence of fire power and tunnel blockage ratio on the variation law of critical wind velocity, the way of comparative analysis between PyroSim fire dynamics simulation tools and empirical formula was applied. The reduced size model of tunnel was established, and the reliability of grid size division in the model was checked. It was found that the most reliable grid size is one-tenth of fire characteristics diameter. The results showed that the simulated critical wind velocity is consistent with the theoretical critical wind velocity. The critical wind velocity increases with the increase of fire power, and it tends to be stable when the fire power is larger than a certain range. The critical wind velocity is affected by the blocking action of train to tunnel. It decreases linearly with the increase of blockage ratio in cross sections of tunnel, and it tends to be stable when the blockage ratio reaches 40%.