为研究动态火源对隧道拱顶温度场分布影响规律,针对隧道中动态火源火灾,在自然通风条件下,静止、40km/h及60km/h等速度的20MW火源在隧道内穿行的火灾过程,采用火灾动力学模拟器Fire Dynamic Simulator(FDS)进行火灾场景的模拟与计算.重点对火源在隧道行进过程中拱顶沿纵向温度分布、温度峰值变化规律及影响因素进行分析.研究结果表明,通风是影响隧道火灾温度的主要因素,移动火源在一定程度上打破了隧道内由于顶棚射流引起的热烟气与冷空气的动态循环机制,活塞风尾段涡流会引起隧道流场变化,一定程度阻碍了燃烧释放热量向火源行进逆向的扩散,并将高温气流带向其运动方向.

Aiming at the accidents caused by moving fire source, for analyzing the influence law of moving fire on ceiling temperature of tunnels, through Fire Dynamic Simulator (FDS), the processes that fired vehicle with 20MW Heat Release Rate (HRR) travels at the speed of 0km/h (static in tunnel), 40km/h, and 60km/h, respectively in tunnel with natural ventilation are simulated. The longitudinal temperature distribution, change law of peak temperature, and its influence factors when moving fire stops and becomes stable combustion in tunnel are specially analyzed. It indicates that ventilation is main influential factor to the temperature in tunnel fire. Moving fire causes air turbulence and breaks the circulation balance of hot smoke and cold fresh air caused by ceiling jet in tunnel, making tunnel fire process more complicated. On one hand, the airflow filed movement induced by piston wind wake of moving fire promotes mixture and combustion of fuel and air, on another hand, it blocks the spread of heat released in the direction opposite to fire movement in certain degree and also entrains high temperature airflow into its spread. The research provides guidance for the study on mechanism of tunnel fire with moving fire as well as relevant fire fighting and rescue technique.