Study the Influence Factors of Semi-transverse Ventilation and Smoke Exhaust Effect in Subway Tunnel

李昂

朱常琳

硕士

西安建筑科技大学

半横向通风排烟;;隧道模型;;列车模型;;模型实验;;数值模拟

地铁隧道是一个狭长且较为封闭的空间,与外界的连通口有限。如果列车在区间隧道中部着火且无法行驶到下一站的情况下,火灾产生的大量高温烟气将会对乘客的生命安全构成严重的威胁。地铁隧道排烟系统就是将火灾产生的烟气及时的排出,给乘客一个较为安全的疏散空间。纵向排烟方式是目前最为常见的地铁隧道排烟方式,但这种方式有一个弊端,就是当列车中部着火的时候,无论从哪一侧排烟,总有一部分乘客置于烟气之中。为了解决这一问题,人们提出全横向排烟和半横向排烟两种方式。全横向排烟方式由于投资较大,占用隧道空间较多,故很少采用。半横向排烟方式具有其它两种排烟方式的优点,能保证绝大部分乘客不被烟气湮没,是一种较为理想的地铁区间隧道排烟方式。本文假定列车车厢中部着火且无法继续行驶的情况下,利用数值模拟与实验两种方法研究排烟道高度、排烟口开启个数以及排烟风速对半横向通风排烟方式排烟效果的影响。本文选取某地铁区间隧道为原型,根据弗诺德模型,建立了比例为1:10的模型隧道,模型隧道长15m,断面尺寸为0.72m×0.48m。此外,本文利用FDS数值模拟软件建立了全尺寸地铁区间隧道物理模型,对地铁区间隧道半横向通风排烟的排烟效果进行了数值模拟研究。具体研究包括以下内容:1)建立了比例为1:10的地铁区间隧道模型实验台,研究了火源强度为5MW时,烟气自然填充、自然通风排烟和半横向通风排烟的排烟效果。2)利用实验方法研究了火源强度为5MW时,不同排烟道高度、排烟口开启个数及排烟风速对半横向通风排烟效果的影响。3)利用FDS软件数值模拟研究了自然填充、自然通风排烟和半横向通风排烟这三种排烟方式下的烟气蔓延情况、隧道温度和CO浓度的分布情况,并且对比了数值模拟结果和实验结果下的顶棚温度和人眼特征高度处的温度,验证了数值模拟的可靠性。此外,利用FDS数值模拟研究了不同排烟道高度、排烟口开启个数及排烟风速对半横向通风排烟效果的影响。

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.