隧道集中排烟模式下火灾数值模拟研究

Numerical simulation study on tunnel fire under central smoke extraction system

运用火灾动态模拟软件FDS对采用独立排烟道集中排烟的隧道火灾进行了模拟。通过研究12种不同排烟阀开启方案下隧道内的烟气温度和蔓延规律,得出了排烟阀设置参数对集中排烟模式控烟效果的影响,提出了排烟阀设置的优化方案的参考参数。结果表明,排烟阀的开启个数、间距、单个面积等参数是共同作用影响隧道内的温度和烟气蔓延的。当排烟阀开启8个,间距25m,单个排烟阀面积为8 m^2或排烟阀开启6个,间距25 m,单个排烟阀面积为8 m^2时,隧道排烟系统的控烟效果较好。

The paper is trying to find out the influence of the configurations of exhaust inlets on tunnel fire which adopting the central smoke extraction system. This new exhaust mode adopt the design concept of separating gas from tunnel through independent exhaust flue. It is seldom used and many factors which related to the effect of smoke extraction are lack of system specifications, it costs a lot doing tunnel physical tests, besides numerical simulation of tunnel fire research develops fast and maturely. So the fire dynamics simulation software FDS is used to simulate tunnel fire under the central smoke extraction system. The gas temperature and spreading distance in the tunnel are studied by comparing 12 cases whose exhaust inlets have different opening types. By sorting the 12 cases, the smoke temperature inside the tunnel and smoke spreading distance of the 12 cases are analyzed. According to the research, the influence of the configurations of exhaust inlets on the effect of controlling smoke using central smoke extraction system is obtained. The optimization setting parameters of exhaust inlets are proposed. The results show that, the parameters of exhaust inlets which involve different opening number, different spacing or different single area have a combined impact on the temperature inside the tunnel and the smoke spreading distance. Blindly decreasing or increasing one parameter is not reasonable for the smoke extraction effect and the tunnel construction investment. There are two cases which have the better smoke controlling effect among the 12 cases. They are case 3 （the opening number, spacing and single area of exhaust inlet is respectively 8 m, 25 m, and 8 m^2 ） and case 6 （the opening number, spacing and single area of exhaust inlet is respectively 6 m, 25 m and 8 m^2） . The researches provide a basis and reference for the design of similar tunnel ventilation exhaust system.