排烟口附加组合挡板对隧道火灾排烟效果的模拟研究

Simulation study on the effect of additional combined baffle under the smoke exhaust port on smoke exhaust of tunnel fire

建立单孔隧道模型,采用FDS数值模拟分析不同高度的组合挡板对隧道机械排烟的影响。结果表明,相较于普通排烟口,安装组合挡板可以有效提高隧道机械排烟效率,改善排烟口处气体压力场的分布状态,减小垂直方向的排烟风速,加大水平方向的排烟风速,从而降低吸穿现象发生概率。经模拟验证,发现组合挡板高度是影响吸穿现象发生的重要因素,组合挡板会使排烟口前方烟层厚度变小,当烟层厚度小于挡板高度时就会发生吸穿现象。通过比较挡板高度分别为50、65、80、95、110 cm几种情况的模拟效果,发现H=50 cm工况排烟口处的烟气浓度最高,单位时间排烟量最大,排烟效果最好。

Single hole tunnel model was established and the influence of the combined baffles on the mechanical exhaust of the tunnel was analyzed by FDS.The results showed that compare to the normal smoke exhaust port,the installation of combined baffles can effectively improve the mechanical exhaust efficiency of the tunnel,improve the distribution of the gas pressure field at the exhaust vent,reduce the vertical exhaust air velocity,and increase the horizontal smoke exhaust wind speed,thereby reducing the probability of occurrence of plug-holing.Through simulation verification,it is found that the height of the combined baffles is an important factor affecting the occurrence of plug-holing.The combined baffles will make the thickness of the smoke layer in front of the smoke exhaust port smaller,and the plug-holing will occur when the thickness of the smoke layer is less than the height of the baffle.By comparing the simulation results of the baffle heights of 50,65,80,95,110 cm,it is found that the flue gas concentration at the exhaust vent is the highest when H=50 cm,the smoke exhaust per unit time is the largest,and the smoke exhaust effect is the best.