降雨与纵向通风作用下隧道火灾烟气蔓延及分层特性试验研究

Experimental study on smoke movement and stratification characteristics of tunnel fire under the effect of rainfall and longitudinal ventilation

为了应对极端降雨天气对隧道火灾的烟气防控带来的挑战,基于Froude相似准则建立缩尺隧道火灾试验平台,研究降雨与纵向通风耦合作用下的隧道火灾烟气蔓延规律、垂直温升特性及烟气分层状态。试验结果显示:降雨诱导产生的纵向气流阻碍烟气向降雨侧蔓延,随着降雨强度增大,烟气逐渐被控制在通风侧,通风侧烟气层厚度增大;启动纵向通风后,烟气同时受到降雨诱导气流和强制通风气流的作用,烟气与冷空气的掺混加剧,烟气层厚度增加;随着纵向通风速度持续增大,烟气逐渐被控制在隧道降雨侧,烟气发生沉降;降雨强度增大和通风速度增大都会破坏烟气的稳定分层,当纵向通风气流与降雨产生的诱导气流强度相当时,隧道内烟气分层保持相对稳定。

In order to cope with the challenge of smoke control in tunnel fire caused by extreme rainfall,a scaled tunnel fire test platform was established based on Froude similarity criterion,and the law of smoke movement,vertical temperature rise and stratification of smoke under the effects of rainfall and longitudinal ventilation were investigated.The results showed that the longitudinal airflow induced by rainfall would hinder the movement of smoke to the rainfall side.As the rainfall intensity increased,the smoke was gradually controlled on the ventilation side,and the thickness of the smoke layer increased.After longitudinal ventilation running,the smoke was affected by both rainfall-induced airflow and forced ventilation airflow.The mixing of hot smoke and cold air intensified under the combined effect of the two airflows,and the thickness of the smoke layer increased.As the longitudinal ventilation velocity continuously increased,the smoke was gradually controlled at the rainfall side,and the smoke settled to the lower space of the tunnel.The increase of rainfall intensity and ventilation velocity destroyed the smoke stratification.When the longitudinal ventilation airflow was equal to the rainfall-induced airflow,the smoke stratification could be maintained stable.