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隧道集中排烟系统的排烟风量是影响火灾烟气抽排效果的关键参数。量化评价烟气抽排效果有利于排烟风机的优化选型。基于FDS的火灾燃烧过程的化学反应式得到隧道火灾烟气的质量生产速率,提出了排烟效率和排烟效能两个表征集中排烟系统烟控能力的计算公式。用基于大涡模拟的FDS软件对隧道火灾烟气进行数值模拟计算。对比研究表明,随着排烟风量的增大,机械排烟效率增大,机械排烟效能反而降低。风机排烟风量增大使多个排烟阀处发生吸穿现象,但风流短路并未降低整个排烟系统的排烟效率。根据研究结果给出了合理的风机排烟风量设计区间,确定三阳路道路隧道集中排烟系统的最佳排烟风量为170m3/s,对应的排烟效率为96.3%。
The smoke exhaust volume of the tunnel smoke exhaust system is the key parameter that affects the smoke exhaust effect of the fire. The quantitative evaluation of flue gas extraction effect is conducive to the optimization of exhaust fan selection. Based on the chemical reaction of FDS-based fire combustion process, the mass production rate of flue gas from tunnel fire was obtained, and two formulas for calculating the smoke control ability of the centralized smoke extraction system were proposed. FDS software based on large eddy simulation was used to simulate the smoke of tunnel fire. The comparative study shows that with the increase of exhaust air volume, the efficiency of mechanical exhaust fumes increases, but the mechanical exhaust efficiency decreases. The increase of exhaust air volume of the fan exhausts many exhaust valves, but the short circuit does not reduce the exhaust efficiency of the entire exhaust system. According to the research results, the reasonable design range of fan exhaust air volume is given, and the best exhaust air volume is 170m3 / s and the corresponding exhaust efficiency is 96.3% for Sanyang Road Tunnel.