非直线型公路隧道火灾烟气迁移特性的数值模拟

Numerical Simulation of Fire Smoke Propagation in a Non-straight Road Tunnel

针对以往的火灾试验和数值模拟研究大多是在直线型隧道中进行的这一特点,以一非直线型公路隧道为研究对象,在全尺寸试验的基础上,针对不同的火源位置和火灾应急通风方案,对于火源功率为30 MW火灾的烟气运动与控制规律进行了数值模拟。结果表明:不同应急通风方案的烟气控制性能有很大差异;纵向风速对烟气迁移具有显著的影响;纵向风速增大,烟气回流现象显著减轻,但烟气前锋的运动亦同时加快;火源位于隧道圆弧形区域时,火源区纵向风速接近于零,阻碍了烟气沿隧道纵向的运动;现有的应急通风方案均不能有效控制烟气回流,应辅以其他通风措施。

Numerical simulations for fires of 30MW for different fire locations and ventilation scenarios are conducted based on full scale experiments in a non-straight road tunnel due to the fact that most fire experiments and simulations are carried out in straight tunnels before.Results show that the performance of different ventilation scenarios differed from each other largely;longitudinal velocity had a strong influence on the propagation of smoke;smoke backlayering became weaker and smoke front moved faster with the increase of longitudinal velocity;the movement of smoke in longitudinal direction is hindered by the small longitudinal velocity of about zero in the vicinity of a fire located in the curved section of the tunnel;the existing emergency ventilation system cannot prevent backlayering effectively,other ventilation measures have to be provided.