十字平交通道不同排烟模式烟控效果的数值模拟研究

十字平交通道是主、辅通道在中间位置十字相交的一种较为少见的城市道路形式,火灾情况下烟气运动和通风排烟策略不同于常规意义上的公路隧道。采用FDS模拟软件研究辅通道三种通风排烟模式的烟控效果,综合考虑不同火灾规模、射流风机位置、射流形式等的影响作用。结果表明:辅通道单侧射流、两侧同向射流和两侧相向射流作用均存在最小临界风速。火灾规模为0 MW~30 MW,最小临界风速值随火灾规模变化关系为:Y=Y0+bX。两侧相向射流对应最小临界风速最大,烟气层结构破坏严重,火场温降效果最差;单侧射流和两侧同向射流对应的最小临界风速值较小且差别不大,结合工程实际情况,考虑单侧风机射流模式为较合理优化的烟控方式。

Numerical simulation study on smoke control effect of different smoke exhaust modes in vertical crossroads

The crossroads are relatively rare urban roads in which the main and auxiliary channels intersect vertically at the middle. Fire smoke movement and the way of smoke evacuation are different from the conventional road tunnels. In this paper, for different fire scales, jet fan positions and jet forms, FDS simulation software is used to study the effect of the smoke control with three ventilation modes in the auxiliary channel. The results indicate that there is a minimum critical ventilation velocity on the unilateral jet and the bilateral jet between the coherent and the opposite in the auxiliary channel. In the range of 0-30 MW, the minimum ventilation velocity depends linearly on the fire scale. The minimum critical ventilation velocity is the largest on the bilateral opposite jet, which damages the smoke layer seriously and makes the temperature decrease slowly. The minimum critical ventilation velocity is small and differs slightly for the unilateral jet and the bilateral coherent jet. The unilateral fan jet is considered to be the best smoke control method for practical application.