自然通风倾斜隧道火灾烟气最大逆流长度研究

Study on smoke maximum back-layering length in a ventilated inclined tunnel fire

为探讨纵坡隧道利用烟囱效应诱导气流进行火灾烟气控制的可行性,系统开展了烟囱效应作用下倾斜隧道火灾烟气流动规律研究。揭示了倾斜隧道中由坡度产生的烟囱效应作用对火灾烟气蔓延规律的影响,分析了自然通风条件下的倾斜隧道火灾烟气非对称流动效应。结果表明,随着高程差的增大,正向流动的烟气、空气质量流量从50%增加至约100%;而负向流动的烟气、空气质量流量从50%衰减至约0%。利用高程差作为特征参数进行定量表征,提出了火灾烟气与新鲜空气的质量流量经验公式,并推导出了烟气最大逆流长度预测公式。

In order to study the feasibility of fire smoke control in inclined tunnel by using environmental wind induced by stack ef-fect,a systematic study on smoke flow distribution in inclined tun-nel under the effect of environmental wind was carried out.The influence of stack effect caused by tunnel slope on smoke flow dis-tribution in inclined tunnel is revealed,and the asymmetric flow effect of smoke in inclined tunnel under natural ventilation is ana-lyzed.Result shows that as the elevation difference increases,the mass flow rate of smoke and air flowing in the positive direction increases from 50%to a value close to 100%,while that flowing in the negative direction decreases from 50%to a value close to 0%.By using elevation difference as the characteristic parameter,the empirical formula of mass flow rate of outflowing smoke and entraining air is presented.In addition,the prediction formula of maximum smoke back-layering length is proposed.