Numerical study on the optimization of smoke ventilation mode at the conjunction area between tunnel track and platform in emergency of a train fire at subway station

To cope with fires in a subway station, ventilation systems are usually installed, which includes an air supply system and a smoke exhaust system. In case of a train fire, the operation of these ventilation systems needs to be studied in order to get optimal control of smoke propagation and provide better environmental conditions for personnel evacuation. In this paper, CFD simulations are carried out by Fire Dynamics Simulator (FDS) to study the effectiveness of different ventilation modes in case of a train fire in a subway station. The temperature and visibility contours are computed as to compare the performance of various ventilation modes for subway stations with full-seal Platform Screen Door (PSD) or half-height safety door. Results show that appropriate activation of the air supply system can improve the efficiency of the ventilation system in smoke control, and vice versa. It is better to activate the lobby air supply system and meanwhile close the platform air supply system. As for the exhaust system, it is necessary to activate the platform exhaust system and the Over Track Exhaust (OTE) system, and it is better to deactivate the Under Platform Exhaust (UPE) system. The optimization strategy of the ventilation mode for subway stations with full-seal PSD is similar to that for subway stations with half-height safety door. With the help of the additional smoke barrier, smoke propagation in a subway station can be well controlled. The results in the paper may serve as a useful reference for the smoke control design in case of subway train fires.     

长大铁路隧道及隧道群救援设施的规划探讨

随着20 km以上的长大铁路隧道及隧道群数量的不断增加,其防灾救援问题日益引起人们的关注。为获得长大铁路隧道及隧道群救援设施的规划方案,在对国内外长大铁路隧道及隧道群进行大量调研的基础上,按列车停车安全距离、火源长度和火灾烟气影响范围将铁路隧道群进行了细化。定义相邻隧道洞口间距小于250 m的铁路隧道为毗邻铁路隧道群,其紧急救援站设置主要考虑隧道内的紧急疏散通道、排烟、站台的加宽和洞口段的扩大;相邻隧道洞口间距在250~400 m的铁路隧道为连续隧道群,不设置紧急救援站;相邻隧道洞口间距大于400 m的铁路隧道为单体铁路隧道,其紧急救援站设置考虑横通道设置和洞内排烟模式。     

着火列车制动进站过程烟气扩散特性模拟

为探究火灾列车制动驶向地下车站进行救援时的烟气扩散特性，采用理论分析和数值模拟的方法研究在不同控制烟气措施下，火灾列车减速至停止过程中烟气在车站轨行区及站台层的扩散规律，以及车站防灾通风系统受到的影响。结果表明：火灾列车制动进站时受移动火源与活塞风两大特性影响，烟气在上下游表现出明显的不均匀、不对称分布规律；屏蔽门虽能有效阻止烟气蔓延至站台层，但同时会增大轨行区活塞风速，增加烟气蔓延速度，不利于安全疏散；受活塞风影响，轨行区排烟效率下降了14%，轨行区各排烟阀火灾中下游排烟效率更高。     

地铁轨顶排热系统协同站台火灾排烟方案研究

以武汉某地铁车站为例,通过数值模拟和实验测试,对地铁车站站台发生火灾时轨顶排热系统协同站台火灾排烟方案和站台端部专用排烟风管方案进行研究。研究表明,轨顶排热系统协同站台火灾排烟方案可行,各楼梯、扶梯口处均能形成向下不小于1.5 m/s 阻止烟气向上蔓延的气流;当轨顶侧排烟口均匀布置时,站台火灾联动设备最少,协同排烟效果最好。站台端部专用排烟风管协同站台火灾排烟方案,在车站楼梯、扶梯口数量较多时,楼梯、扶梯口部阻挡气流风速存在低于1.5 m/s 的风险,应慎重选用。     

Numerical studies on evaluation of smoke control system of underground metro rail transport system in India having jet injection system: A case study

The rail based urban transport system is being developed for national capital of India, New Delhi. The smoke control using ventilation in case of fire inside the tunnel, similar to Delhi Metro corridor has been investigated using computational fluid dynamics technique. A section of tunnel having dimensions 400 m long, 5.5 m wide and 6 m high is considered for simulation. The analysis has been carried out by assuming a variable fire source with a peak heat release rate (HRR) of 16 MW, located at the center of the tunnel. Ventilation ducts are located in the ceiling near the tunnel portals and are inclined at 10 degrees to the plane of the ceiling through which fans discharge air. The influence of the fire HRR curve slope on the smoke flow dynamics in a realistic tunnel model fitted with jet injection type longitudinal ventilation system has been investigated. In case of fire two cases are studied: (1) fans activated immediately after detection, (2) fans activated at delayed times to take into account the response time for the fans to achieve its maximum speed. The velocity of supply and exhaust fans necessary to remove smoke in 30 s from the upstream direction is determined. The velocities of fan required to produce desired critical velocity in the longitudinal direction for different HRR of fire is predicted.     

公路隧道集中排烟道排烟阀结构设计参数研究

针对某大断面公路盾构隧道火灾烟气控制工程实际,为了优化设计公路隧道集中排烟模式下排烟阀结构参数,采用火灾动力学模拟软件FDS构建了隧道数值模型,并根据公路隧道的通行车辆种类、火灾类型和火灾规模,选择了隧道火灾典型场景,设计了集中排烟模式下单向及双向排烟时相应的火灾工况,通过提取隧道顶隔板下方温度场、行车道2 m高处能见度以及排烟阀流速等数据,分析了双向排烟时特定排烟阀面积下不同排烟阀结构形状对隧道火灾排烟效果的影响,进而探讨了单向排烟方式下不同排烟阀面积时的隧道火灾排烟效果。在此基础上,获得了隧道集中排烟模式下合理的排烟阀面积、排烟阀结构形状等设计参数。     

Assessment of ventilation efficiency for emergency situations in subway systems by CFD modeling

The ventilation system is the strategic component of the subway systems when incidents involving heavy smoke occur in tunnels. Consequently, the purpose of this study is to investigate the ventilation efficiency in one of the most severe emergency scenario: train on fire (maximum heat release rate reaching 30 MW due to an ultra-fast fire) and stopped in the tunnel, the incident requiring passenger evacuation. Two ventilation strategies are taken into account: tunnel ventilation fan system (mid-tunnel fan plant located in separate construction) in conjunction with stations mechanical ventilation and end-of-station fan plants in conjunction with stations mechanical ventilation. The analysis is performed using computational fluid dynamics (CFD) modeling. The numerical model proposes an original approach based on the introduction of source terms in conservation equations for energy, carbon monoxide (CO) and carbon dioxide (CO₂), in order to deal with the heat, CO, and CO₂ due to fire. Equations expressing the conservation of CO and CO₂ are specially added to the basic equations governing a turbulent non-isothermal airflow in the CFD model. This method allowed achieving values of velocity, temperature, CO and CO₂ concentrations all over the computational domain. In addition, the modeling and simulation methodology complies faithfully to the real operation of the ventilation systems investigated in normal and emergency (fire) conditions. The results show that both ventilation alternatives taken into account lead to the secure evacuation of passengers all over the simulation time. The evacuation process toward the nearest station is not at all disturbed by too high air velocities, high temperatures or critical CO or CO₂ concentrations.     

长大隧道火灾安全疏散研究

在调研分析国内外长大隧道疏散模式的基础上,以虹梅南路隧道为研究对象,采用CFD软件对不同排烟方式下隧道火灾进行数值模拟,结果表明:不同的排烟方式下隧道内烟雾和温度场纵向分布扩散规律不同,采用单侧排烟时,烟雾向火源下游聚集,温度升高很快,有害气体浓度升高,无法提供合适的逃生环境;而采用双侧排烟时,烟雾向两侧蔓延,浓度和温度较小,满足火灾通风要求。最后,通过数值模拟人员疏散过程,计算结果表明,现有的排烟措施能够满足疏散安全要求。     

A smoke model and its application for smoke management in an underground mass transit station

This paper discusses the development of a smoke model for CFD. The model evaluates smoke visibility based on line of sight. Using a compartment fire, the deficiency in determining visibility by the conventional surface-based approach is first demonstrated. Smoke management in an underground rail station is investigated using the smoke model. For a medium growth rate fire, the results show that the platform is blocked by smoke within 2–3 min. On the mezzanine, the designed smoke exhaust controls the smoke only for a limited time of less than 4 min. The variations of smoke obscuration are quantified at three locations, which are used to start the tunnel ventilation at 4 min. This can be related to a video-based smoke detection. The smoke model would be useful in tenability, egress and other life safety assessments. Future development of the model includes local lighting effects and experimental validation.     

地铁区间隧道火灾排烟通风模式分析

采用理论分析、CFD数值模拟分析等方法对北京某地铁单隧道发生火灾时的通风排烟系统的各种可能运行模式进行了分析,分析结果表明,不同的模式下通风排烟效果相关很大,同时火灾发生的位置不同,相应的最优通风排烟模式也有所不同。     

地铁区间隧道火灾人员疏散微环境的数值分析

本文的研究目的是探讨自然通风模式下地铁区间隧道火灾人员疏散微环境中烟气温度、能见度和CO浓度分布,为地铁隧道火灾防范提供理论依据.采用FDS(Fire Dynamics Simulator)软件模拟列车中部着火且列车停在隧道中部和停在靠近隧道一端站台2种火灾情况下,隧道内纵断面人眼特征高度的烟气温度、能见度和CO浓度分...     

两种地下步行通道火灾排烟模式比较研究

采用理论和FDS数值模拟结合的方法,研究地下步行通道发生火灾（1.5 MW）时,半横向排烟和纵向排烟对地下步行通道内火灾烟气蔓延的控制效果。研究表明,在排烟量相等、送风量不等的条件下,除火源正上方温度超过60 ℃外,半横向排烟模式下火灾参数未达到临界值,有利于行人向火源两侧逃生;纵向排烟模式将火灾参数均控制在临界指标以内,大部分烟气被控制在火源下风侧,有利于行人向上风侧逃生。地下步行通道火灾时,从人员逃生效率以及消防人员应急救援便捷性的角度出发,宜采用半横向排烟模式;从行人受危险因素不确定性影响的角度出发,宜采用纵向排烟模式。     

电客车自动喷水混式系统设计及数值模拟

针对地铁电客车火灾扑救薄弱形势,提出将自动喷水灭火系统进行早期火灾自救,水幕系统用于挡烟阻火,同时开启列车及隧道通风排烟的混式系统设计。结合车辆概况,建立微分能量衡算方程,应用"逐点法"对系统进行水力计算,建立数学模型。以电客车头部着火为例,研究系统开启不同时间温度场的变化,为系统参数合理匹配提供理论支持。使用COMSOL Multiphysics软件对建立的模型进行分析模拟。理论及实例应用表明,通过材料、约束设定及网格划分,该模型在电客车火灾模拟中具有较好的适用性。     

灭火救援专业知识智能匹配算法

摘 要：基于当下灭火救援领域中的突发事件,提出灭火救援专业知识智能匹配算法,该算法基于自然语言处理和注意力机制计算案件描述和消防预警信息之间的语义关系,从而实现相关灭火救援专业知识的匹配。首先基于自然语言处理的方法学习句粒度级别的语义信息,然后基于注意力机制学习词粒度级别的语义信息,最后基于两个级别语义信息的交互,根据信息之间局部差异推断两个句子之间的关系。试验结果表明：该算法具有优异的性能,能够同时从词和句两个粒度上更准确地理解句子,实现基于案件描述的灭火救援专业知识智能匹配。     

海底特长隧道利用横通道控烟技术研究

摘 要：为了解决特长海底隧道发生火灾时的排烟问题,提出利用服务通道和联络横通道辅助送风的通风方案。利用火灾动力学模拟软件（FDS）,建立隧道火灾通风模型,通过研究通风排烟时服务隧道内补风量与横通道开启数量对火灾烟气的控制效果,确定通风系统的技术参数。结果表明：火灾发生时,事故隧道内纵向通风风速2 m/s,同时开启火源上游3 个横通道,并在服务隧道两端各施加1.3 m/s 纵向通风风速,既可将烟气控制在火源一侧,同时不影响人员安全疏散,其控烟效果与通风网络解算结果一致。采用横通道辅助送风的通风方案,控制特长海底隧道内火灾烟气蔓延是具有理论可行性的。     

地铁过江隧道事故通风系统对火灾的影响研究

以某城市地铁过江隧道火灾为例,采用地铁环境模拟软件,计算和分析列车不同着火部位及隧道事故通风系统启动时间对火灾高温烟气分布的影响。结果表明,列车活塞风由于惯性作用将对火灾高温烟气控制产生一定的影响。车头着火时,列车活塞风有利于控制烟气回流,隧道事故通风系统启动越快有利于控制车头烟气温度的升高;车尾着火时,活塞风对控制火灾烟气向车头蔓延产生不利影响,事故通风系统立即启动使车尾烟气温度快速达到最高,可能产生轰燃现象,事故通风系统推迟启动使高温烟气快速向车头方向扩散,不利于人员逃生。建议加强列车车尾自身的消防灭火装置,提高人员灭火救援的自救意识。     

Full-scale experiment and CFD simulation on smoke movement and smoke control in a metro tunnel with one opening portal

Three full-scale model experiments were conducted in a unidirectional tube, which is a part of a metro tunnel with one end connected to an underground metro station and the other end opened to outside in Chongqing, PR China. Three fire HRRs, 1.35 MW, 3 MW and 3.8 MW were produced by pool fires with different oil pan sizes in the experiments. Temperature distributions under the tunnel ceiling along the longitudinal direction were measured. At the same time, CFD simulations were conducted under the same boundary conditions with the experiments by FDS 5.5. In addition, more FDS simulation cases were conducted after the FDS simulation results agreed with the experimental results. The simulation results show that the smoke temperature and the decay rate of the temperature distribution under the tunnel ceiling along the longitudinal direction increase as HRR increases. The smoke exhausts effectively from the tunnel under mechanical ventilation system, whether the emergency vent is activated as a smoke exhaust or an air supply vent. The operation mode of the mechanical ventilation system depends on the evacuation route.     

西安地铁某岛式站台火灾条件下人员疏散环境的数值分析

本文采用FDS软件,对西安地铁2号线某岛式站台端部火源强度为5 MW的火灾工况进行了数值模拟.在采用事故风机(TVF)+站台空调通风与回风(SEF)+站台下侧排烟的强制通风( UPE)模式下,分析了屏蔽门的不同开启模式对能见度、烟气温度、CO浓度、热辐射和新风风速的影响.结果表明,着火6 min时,强制通风可以使站台和进入站台层的楼梯人口处的温度小于60℃,CO浓度小于312.5 mg/m3 (250 ppm);全部或部分开启屏蔽门可以实现站台烟气层向站台隧道的抽吸,增加站台安全撤离区域.     

Simulation of ventilation and fire in the underground facilities

A revised fire outbreak and evacuation simulation model, MFIRE, is presented in the paper. The model provides information for setting up an emergency ventilation scheme, establishing safety procedures and minimizing damage in underground network systems. MFIRE simulates the interdependence between the ventilation system and its pertinent fans and structures, and the changes in ambient conditions and the heat source. A laboratory based fire simulation was conducted in a small physical tunnel network to verify the MFIRE. The rates of air flow and temperature distribution in each tunnel are compared with the simulated results obtained by MFIRE. Regarding air flow, the experimental rates correlate with the simulated results very well. Because of the reduced physical scale of the laboratory model, the simulated temperature distributions do not quite correlate with the laboratory data. MFIRE is employed to simulate a hypothetical fire outbreak in the Taipei Mass Rapid Transit System. The simulation is designed to investigate the direction and rate of air flow, temperature distribution and emergency ventilation responses. The results have confirmed that the proposed “push–pull” ventilation model can exhaust the high temperature air and smoke out of the underground facilities efficiently once the fire breaks out.     

不同隧道排烟模式对站台火灾人员疏散的影响

为探究站台火灾条件下不同隧道排烟模式对地铁人员疏散的影响,以岛式地铁站为研究对象,利用Pyrosim建立火灾模型,并分析4种隧道排烟模式下的楼扶梯入口风速、烟气温度、CO体积分数和能见度的分布。结果表明：单一隧道排烟模式均无法满足安全疏散要求;疏散时间360 s内,在人眼特征高度处,车站隧道排烟模式下的人员疏散经过区域的能见度不能满足疏散要求,CO体积分数、温度、楼扶梯口风速均满足安全疏散要求;3种区间隧道排烟模式下的楼扶梯口风速均无法满足人员安全疏散要求,区间隧道推拉式反向排烟模式最不利于疏散区域烟气散热,区间隧道双拉式排烟模式排烟效果最为显著;火灾烟气的3个潜在危险因素中,相比于温度和CO体积分数,满足能见度在安全范围内的难度更高。