曲线隧道火灾烟气控制临界风速的研究

On the Critical Air Velocity for Fire Smoke Control in a Curved Tunnel

文章以双螺旋隧道实际工程为研究对象,采用数值计算方法对半径为600 m的曲线隧道在火灾工况下临界风速及火灾烟气的流动规律进行了深入研究和分析。结果表明,采用的数值计算方法对Memorial隧道火灾试验进行计算的结果吻合较好。当曲线隧道内发生规模为10 MW火灾时,火灾烟气控制的临界风速为2.5 m/s。降低曲线隧道通风速度,隧道内均出现明显的烟气回流现象,烟气回流层长度和厚度均随着通风速度的降低显著地增加。随着通风速度的提高,火焰的偏转角增大,拱顶最高温度升高。在火灾下游火源点附近断面烟气分布表现出不对称性,之后断面表现出明显的烟气分层分布。

Using the construction of double-spiral tunnels as an example, this paper discusses the critical air velocity and the smoke-flow law in a curved tunnel with a diameter of 600 m determined by numerical calculations. The results given by the numerical calculations agree well with those given by a fire test in the Memorial tunnel： the critical air velocity for fire smoke control is 2.5 m/s for a fire of 10 MW in the curved tunnel; smoke backflow occurs, and the backflow length and thickness increase significantly, when the ventilation velocity decreases; the deflection angle of the flame and the maximum temperature of the vault increase with an increase of the ventilation velocity; and at the downstream of a fire, the smoke around the fire source forms an asymmetric distribution and is followed by an obviously layered smoke.