火灾时期角联管网烟流传播机制研究

Simulation and analysis of the law of smoke propagation in diagonal pipe network during fire

为探究火灾时期角联管网烟气与风网结构耦合变化机制,基于FDS数值模拟技术,在角联分支设置着火点,给定12种出口风速的工况,结合单巷道内烟气蔓延、温度衰减和最高温度理论模型,得到了角联管网内风速-烟气、风速-温度耦合关系。结果表明:Froude数可以较好解释角联管网烟气蔓延行为;角联分支顶棚温度衰减规律表现为指数型,与St数的取值相关;角联分支最高温度随风速变化表现为先增后减;左、右通路烟气逆退距离与风速均呈对数关系,其临界风速分别为2.98,4.32 m/s,右关联点处的温度衰减率要大于左关联点。

In order to explore the coupling change mechanism of the flue gas and the wind network structure of the angle-connected pipe network during the fire period, based on the FDS numerical simulation technology, the ignition point is set at the angle-connected branch, and 12 kinds of working conditions of the outlet wind speed are given, combined with the smoke spread model, temperature attenuation model and maximum temperature model in single tunnel, the coupling relationship of wind speed-flue gas and wind speed-temperature in the angleconnected pipe network was obtained. The results show that the Froude number can better explain the smoke spreading behavior of the angle-connected pipe network. The angle-connected branch ceiling temperature attenuation law is exponential,which is related to the value of the St number. The maximum temperature of the angle-connected branch with the change of wind speed increase and decrease. The smoke retreat distance and wind speed in the left and right passages are in logarithmic relationship, and the critical wind speeds are 2.98 m/s and 4.32 m/s respectively. The temperature attenuation rate at the right associated point is greater than that at the left associated point.