排烟阀设置对隧道集中排烟效果影响研究

为了获得集中排烟隧道中排烟阀设置参数对排烟效果的影响规律,结合某大型过江隧道防排烟工程实际,根据隧道实际交通情况,设定了火源规模,并设计了数组隧道火灾工况,采用火灾动力学模拟软件FDS构建了集中排烟隧道模型,通过对不同火灾工况下隧道内2 m高处能见度、烟气蔓延范围及排烟阀效率等排烟效果指标的定量分析,获得了单向排烟和双向排烟两种集中排烟模式下单个排烟阀面积、间距、开启个数及形状对排烟效果的影响规律。结果表明：无论单向排烟还是双向排烟,单个排烟阀面积、间距及开启个数三种因素共同影响着排烟效果,一味的通过增大或减小其中的一个因素来提高排烟效果的做法是不可行的;但相同的排烟阀设置即相同的单个排烟阀面积、间距及开启个数时,单向排烟模式比双向排烟模式隧道内烟气蔓延距离小,但总排烟阀效率要低于双向排烟时的排烟阀效率,同时,单个排烟阀形状为矩形时排烟效果较好。

Study on Effect of Configuration of Exhaust Inlets on Central Extraction with Top Exhaust System in Tunnel Fire

In order to obtain effect of configuration of exhaust inlets on central extraction system in tunnel fire,combing with fire smoke control engineering practice of a large underwater tunnel,the scale of fire was set and the array tunnel fire conditions were designed according to the tunnel actual traffic conditions.At the same time,tunnel model with the central exhaust system was built by using the fire dynamics simulation software FDS.The smoke extraction effect index such as visibility at a distance of 2 m above the ground along the tunnel,smoke spreading distance and efficiency of smoke extraction was analyzed quantitatively.And then,the influence laws of the smoke extraction effect of configuration of exhaust inlets such as size of the single exhaust inlet,spacing,the opening number and shape of the single exhaust valve on central extraction under uni-directional smoke exhaust mode and bi-directional smoke exhaust mode were obtained.The results showed that： the three factors of size of the single exhaust inlet,spacing and the number of opening exhaust inlet influence collectively smoke extraction effect whether uni-directional or bi-directional smoke exhaust mode.The approach of blindly improving the effect of smoke extraction through the increase or decrease of a factor is not feasible;the smoke spreading distance under uni-directional smoke exhaust mode is smaller than that under bi-directional smoke exhaust mode.However,the total efficiency of the exhaust inlets is below that of the bi-directional smoke exhaust when the same configuration of exhaust inlets such as size of the single exhaust inlet and spacing as well as the number of opening exhaust inlets is used.Simultaneously,the effect of smoke extraction is better when the shape of a single exhaust is rectangle.