侧向排烟系统排烟口机械排烟数值分析

摘要

FDS was used to research the lateral smoke extraction system in road tunnel and the temperature of smoke layer interface was calculated by the N-percentage method.The plug holing phenomenon in fire was researched too.The changing of temperature,depression of smoke layer and mass fraction of carbon monoxide near the smoke vent were investigated to study the efficiency of the mechanical smoke exhaust in lateral smoke extraction system.Results showed that an appropriate increase in the amount of volumetric flow rate can exhaust smoke rapidly and decrease the temperature in the ceiling,however,may cause the plug holing phenomenon and lead to reduction of exhaust effect.The smoke should cover half of the smoke vent and the volumetric flow rate of a single smoke vent should range from 4.5 m/s to 6.0 m/s,to get better exhaust effect.%针对侧向排烟系统在隧道中的应用,采用FDS数值模拟,根据N百分法计算分界面温度,研究隧道发生火灾时排烟口吸穿现象.通过分析排烟口处的温度、hDEP和CO质量分数变化研究侧向排烟口的排烟效率.研究表明:适当增大排烟风速可以加快烟气排出隧道,同时降低隧道顶棚处温度,但是排烟风速过大会造成吸穿现象,导致排烟效率低.为保证排烟效率,应控制烟气层覆盖至少一半排烟口,单个排烟口的排烟风速宜取4.5～6.0 m/s.