不同火源功率及火源—出口距离对隧道火灾临界风速的影响研究

由于隧道特殊的建筑结构，其发生火灾时的危害性，相比于其他类型的火灾要严重的多。在隧道的消防设计中，运用纵向风排烟是隧道火灾一项重要的消防措施，如何利用纵向风的特性来有效地引导隧道火灾烟气的运动需要进行系统的研究。运用FDS数值模拟的方法进行研究。结果显示，临界风速随着火源功率的增大而增大；并且随着火源与隧道出口距离的增大呈现出线性增长的趋势。对于6.0cm和9.0cm的火灾，临界风速与火源-出口距离关系式分别为 y=0.4+0.14x, y=0.5+0.11x。因此在消防实际应用中，应当充分考虑不同火源功率和火源在隧道中的相对位置对火灾烟气运动的影响，调节不同的排烟风速进行有效、合理的隧道排烟。

Study on effect of different fire HRR and fire-exit distances to critical wind velocity in tunnel fires

Due to the special building structure of tunnels, the tunnel fire will impose more hazards than other kinds of building fire. Among complex tunnel fire protection designs, the smoke exhaust by longitudinal ventilation is one of the most important fire protection measures in tunnels fire, while how to utilize the characteristics of longitudinal ventilation to effectively lead the movement of tunnel fire smoke needs to be studied systematically. In this paper, the FDS numerical simulation method was used to study the influence of different fire heat release rate (HRR) and different fire-exit distances to the critical wind velocity. It was found that, the critical velocity increases with the increasing fire HRR, and it shows a linear increasing trend with the increase of fire-exit distance. With regard to 6.0 cm and 9.0 cm fire scenarios, the relationship formula of critical wind velocity and fire-exit distance is y=0.4+0.14x and y=0.5+0.11x respectively. Thus in the real practice of tunnel fires protections, it is strongly suggested to consider the influence of different fire HRR and the relative positions of fire in the tunnel to the movement of fire smoke, and adjust the different wind velocity for smoke exhaust to conduct effective and reasonable smoke exhaust in tunnel.