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