横通道通风对隧道火灾烟气蔓延影响的数值模拟研究*

为探究隧道横通道通风对隧道火灾烟气蔓延的影响规律，使用火灾动力学模拟软件FDS，对不同火源位置的横通道临界风速、主隧道温度分布以及烟气层高度进行研究。研究结果表明:在一定火源功率范围内，隧道横通道临界风速与火源功率的1/3次方成正比且火源距横通道越远，临界风速越小；当火源位于交叉口，横通道使用临界风速通风时，隧道内烟气温度明显降低，烟气迅速沉降到2 m以下；当火源距离交叉口10，20 m，横通道通风会加快火源下游烟气沉降，烟气沉降速度随横通道通风速率的增大而增大；当火源位于交叉口时，烟气沉降由横通道通风对烟气的降温作用和涡旋作用共同主导，当火源位于距离交叉口10，20 m时，烟气沉降主要由涡旋作用主导。

Numerical simulation study on influence of cross-passage ventilation on spread of tunnel fire smoke

In order to explore the influence of cross-passage ventilation on the smoke spread of tunnel fire,the fire dynamics simulation software FDS was used to study the critical wind velocity of cross-passage,the temperature distribution of main tunnel and the height of smoke layer under different fire source locations.The results showed that within a certain range of fire source power,the critical wind velocity of tunnel cross-passage was proportional to 1/3 power of fire source power,and the farther the fire source was away from the cross-passage,the smaller the critical velocity was.When the fire source was located at the intersection and the cross-passage was ventilated with critical wind velocity,the temperature of smoke in the tunnel decreased obviously,but the smoke would quickly settle to below 2 m.When the fire source was 10 m and 20 m away from the intersection,the cross-passage ventilation would accelerate the downstream smoke settlement of fire source,and the smoke settlement velocity increased with the increase of the cross-passage ventilation rate.When the fire source was located at the intersection,the smoke settlement was dominated jointly by the cooling effect of cross-passage ventilation on the smoke and vortex effect,and when the fire source was located 10 m and 20 m away from the intersection,the smoke settlement was mainly dominated by the vortex effect.