Study The Influence Factors Of Semi-transverse Ventilation And Smoke Exhaust Effect In Subway Tunnel

Subway tunnel is a narrow and relatively closed space, with limited outside communication port. If the fire happens in the middle of train and the train can't travel to the next platform, a large number of high-temperature flue gas will make a serious threat to safety of passengers. Subway tunnel Smoke exhaust system of subway tunnel can discharge the gas timely, and give passengers a safe evacuating space. Longitudinal ventilation is the most widely used in subway tunnel, but there is a drawback of this approach is that when the fire happens in the middle of the train, no matter which side of the smoke, part of passengers will stay in the spread range of the smoke. Semi-transverse ventilation and transverse ventilation are made to solve this problem. Thanks to its high initial investment and complex structure, the transverse ventilation is rarely used. Semi-transverse ventilation has the advantage of the other two methods, to ensure that the vast majority of passengers will not be stay in smoke. So it is an ideal way of subway tunnel smoke exhaust. This paper assumes that the fire happen in central of train and cannot continue to drive, using the method of numerical simulation and experiment study how the exhaust velocity,the height of flue and the number of opening exhaust outlet impact the smoke exhaust effect of semi-transverse ventilation.One subway tunnel was selected as the prototype in the paper, a subway tunnel model with the reduced-scale ratio of 1:10 for experiment was established according to Froude-number model, the length of model was designed as 15 m, the section size is 0.48m×0.72 m. In addition, we use FDS numerical simulation software to establish a full-size metro tunnel physical model, to study the effect of smoke subway tunnel semi-transverse ventilation exhaust of the numerical simulation. Specific studies include the following:1)Firstly we established a tunnel model with the reduced-scale ratio of 1:10. The smoke exhaust effects of natural smoke filling, natural ventilation and semi-transverse ventilation were studied and compared through the experiment with heat release rate of 5MW.2)how the exhaust velocity,the height of flue and the number of opening exhaust outlet impact the smoke exhaust effect of semi-transverse ventilation were studied through the experiment model with heat release rate of 5MW.3)FDS was used to build a full-size tunnel model. We studied the smoke spread, the temperature and CO by numerical simulation of smoke filling, natural ventilation and semi-transverse ventilation. To verify the reliability of the numerical simulation,we compared numerical simulation results and experimental results at characteristics of the human eyes and ceiling temperature. In addition, how the exhaust velocity, the height of flue and the number of opening exhaust outlet impact the smoke exhaust effect of semi-transverse ventilation.