公路隧道纵向通风对火灾烟气分层影响研究

纵向通风目前是我国长隧道使用最多的通风排烟方式。通过1∶ 10隧道模型火灾排烟试验,利用激光片光观测火灾烟气分层结构,分析了纵向通风对火灾烟气分层结构的影响;通过数值模拟,研究了隧道采用纵向通风排烟的效果。结果表明:在无风情况下,火灾初期烟气能够较好地维持在隧道顶部,与空气分层界限明显;开启纵向排烟后,能够有效抑制火灾烟气向火源上游蔓延,但烟气分层结构遭到破坏并随着风速增加逐渐消失,火源下游区域能见度下降;纵向排烟风速维持在临界风速及以下,可降低纵向风对烟气分层的影响。

Influences Study of Longitudinal Ventilation on Smoke Stratification in Tunnel Fires

Currently longitudinal ventilation is used in most of long tunnels of our country. Experiments were conducted in a 1∶ 10 scale model tunnel. Smoke stratification pattern was measured by laser sheet, and the influence of longitudinal ventilation to smoke stratification was analyzed. Smoke exhaust effect of longitudinal ventilation in tunnels was study by numerical simulation. The results show that an upper buoyant smoke layer is formed with a cold smoke-free layer below under the condition of no wind. The smoke stratification was destroyed and prevented from spreading upstream as smoke-exhaust fans started, while the visibility of downstream area of fire source was reduced. The influence of longitudinal ventilation to smoke stratification can be reduced, while the velocity of longitudinal smoke-exhaust kept at or below the critical velocity.