基于FDS的公路隧道火灾温度分布和烟气回流分析

Analysis on Temperature Distribution and Smoke Reflux of a Fire Road Tunnel by the FDS Numerical Simulation

采用Pyro Sim建立模型进行FDS数值模拟,得到隧道不同坡度段在不同通风速度下发生火灾后的纵向断面温度分布和烟气流动情况,分析得出:在相同的通风速度下,上坡坡度越大或下坡坡度越小,烟气越易向火源下游排出,越利于减小烟气回流距离;若通风速度增加所引起火源处单位时间内随烟气往下游排出热量的增加量为?Q1,而通风速度增加引起火源处单位时间内烟气向上游的回流程度减小所致单位时间随烟气向上游扩散热量的减少量为?Q2,则当?Q1<?Q2时,火源附近平均温度上升,当?Q1>?Q2时,火源附近平均温度下降;拟合得出5%下坡段隧道的烟气回流长度与通风速度的关系式。

Temperature distribution of vertical section and smoke flow when ventilation is at critical velocity and different ventilation velocity in different slope fire tunnel were obtained by building model and making numerical simulation with PyroSim software. Conclusions are summarized as follows： at the same ventilation speed, the bigger the slope of ascent is or the smaller the slope of downgrade is, the easier smoke exhaust downstream and the shorter smoke reflux distance is. The unit time increased heat exhausted to outside with smoke downstream near the fire source caused by increased ventilation speed is denoted as △Q1 and the unit time decreased heat spread upstream with smoke near the fire source caused by increased ventilation speed is denoted as △Q2. If △Q1 〈△Q2, the average temperature near the fire source will rise. And if△Q1 〉△Q2, the average temperature near the fire source will drop; Obtained the relationship between reflux distance and ventilation speed of downgrade tunnel with a slope of 5% by fitting to simulated data.