【作者】 杨晖；

【导师】 贾力；

【作者基本信息】 北京交通大学 ， 载运工具运用工程， 2010， 博士

【摘要】 本文以北京地铁典型站台和隧道为原型,采用三维数值方法研究了正常运行及火灾条件下地铁空间的空气环境,并采用现场测试和模型实验对部分模拟结果的可靠性进行了对比分析。论文的主要工作包括：采用瞬态数值模拟方法研究了地铁列车运动所形成的活塞风对典型岛式站台空气环境的影响、屏蔽门和空调系统与活塞效应对站台空气环境的综合作用,同时在地铁站台进行了现场测试。研究结果表明列车通过会引起站台局部区域流速超过5m／s,并有超过4℃的明显温升。全封闭式屏蔽门能够增大隧道内活塞风井的换气量。半封闭式安全门能够有效降低乘客候车区域的活塞风速,同时各出入口和隧道活塞风井的空气流量和流动方向没有十分明显的变化；利用稳态数值模拟和模型实验研究了不同火源设置和热释放率条件下纵向通风对控制隧道烟气流动的作用、临界通风速度的变化规律、临界通风条件下隧道顶部最高烟气温度和火源上方回流烟气温度与临界通风速度变化趋势之间的关系,将模拟结果与实验结果和既有研究成果进行了对比分析。研究表明火源条件设定对于数值模拟结果有显著影响,对于热释放率较小的火灾,采用单纯热源模型预测临界通风速度较安全。临界通风状态时,数值模拟预测的下游烟气温度高于实验值。分阶段采用三维瞬态数值模拟研究了活塞效应所形成的非均匀初场对隧道中火灾烟气流动特性的影响,模拟结果显示如果地铁列车因为火灾停在隧道中,在短时间内列车运动所造成的惯性气流会对火灾烟气扩散有显著的影响,应当在制订火灾安全方案中加以考虑。更多还原

【Abstract】 Based on Beijing typical subway station and tunnel, three-dimensional CFD (computational fluid dynamics) method was used to study air environment under both normal and fire emergency conditions. Some simulation results are compared with in-situ measurements and small-scale experiments. Main research works include:The influences of the piston wind caused by train’s movement, PSD (platform screen door) and air-conditioning system on air environment were investigated using transient numerical simulations. Some in-situ measurements were conducted to validate the simulations. The results show that over 5 m/s air velocity and 4℃temperature enhancement is aroused by piston effect in some platform locations. Air flow rate through tunnel ventilating shafts increases greatly after full closed PSD is installed on the platform. 2.5 m high partial closed PSD has not distinct influence on air flow rate through the exits and tunnel ventilating shafts.Numerical simulations and small-scale experiments were conducted to study the effect of the longitudinal ventilation on tunnel fire smoke movement characteristics, the critical ventilation velocity, the maximum smoke layer temperature and the relationship between the critical ventilation velocity and the back-layering temperature above fire source for different fire source conditions (heat fire source and combustion fire source) and heat release rates. The simulation results were compared with the previous study and the small-scale experiments. It shows that the choice of the fire source model has significant influence on simulation results. Simplified heat source without consideration of the combustion mechanisms (heat fire source) would over predicate the critical velocity. The down stream smoke layer temperature under the critical ventilation state predicted by simulations with different fire source models are higher than that measured in small-scale tests.The influence of the heterogeneous air velocity field caused by piston wind on smoke movement characteristics in subway tunnel was studied using three-dimensional CFD method. The results show that as the train fires and stops in the tunnel, the inertial air velocity field has significant influence on smoke movement characteristics at the first few minutes of fire disaster, which should be considered in setting reliable fire evacuation plan.更多还原