活塞风对地铁隧道内烟气扩散特性影响的数值模拟

Numerical Simulation of Piston Wind Effect on Smoke Diffusion Characteristics in Subway Tunnel

研究目的是探索地铁列车活塞运动所造成的隧道内三维非均匀初场对列车火灾烟气扩散特性的影响。采用计算流体力学(CFD)方法模拟列车从运动到停止于隧道中的过程,通过将瞬时计算域内三维速度场经过数据转换和传递作为进一步模拟火灾烟气扩散过程的初始条件,检验有效疏散时间内列车附近疏散空间的安全性,并将模拟结果与静止初始条件下的模拟结果进行对比。模拟所采用的三维非均匀初场更接近于真实的物理过程,使模拟结果更有助于揭示实际火灾过程的本质。模拟结果显示列车运动所造成的惯性气流对火灾早期烟气扩散有显著的影响,所采用的研究方法和结论能为制定更加可靠和安全的火灾应急预案提供理论依据。

The purpose is to study the effect of three-dimensional asymmetric initial field caused by train piston movement on smoke diffusion characteristics in subway tunnel. The velocity fields from the train＇s decelerating process to stopping are simulated by using of computational fluid dynamics （ CFD ） method and the three-dimensional transient field data are adopted as the initial condition for further fire smoke diffusion simulation. The result is compared with that obtained under steady initial field condition. It shows that the inertial air velocity field caused by train＇s movement has significant influence on fire smoke diffusion at the first few minutes. Three-dimensional asymmetric initial field utilized by this simulation approaches the real physical process better, which benefits for demonstrating the fire characteristics. The employed method and its simulation result could provide theoretical basis for establishing a more effective fire emergency plan in subway.