圆筒形地下立体停车库火灾火源位置与火势蔓延规律研究

选取一个典型的圆筒形地下立体停车库作为研究对象,运用star-ccm+软件,采用数值模拟的方法对车库内自然通风条件下的火灾场景进行模拟计算。分别选择负一层、负六层以及负十层作为起火点,计算得出:火源位置越深入地下,着火车位顶棚中心温度越高,最高可达942℃,与起火点同层的车位顶棚中心温度均高于200℃。当某车辆发生火灾后,其相邻车辆、上方车辆、相对车辆将分别在起火后的240、312、322 s左右被引燃;火源位置越往下,引燃附近车辆的时间越短。同时,通过计算值与理论值的对比,讨论了计算火源附近车辆被引燃时间理论公式的适用性。     

固体推进剂燃烧诱发热烟气运动的大涡模拟

利用空间火蔓延与烟气运动的大涡模拟方法,探讨了固体推进剂燃烧时在舱室内形成的火蔓延和烟气的运动,计算出室内烟气温度、墙壁温度与地面热流密度随时间的变化,与试验结果相符合.计算结果表明,固体推进剂火灾初期室内的气体受到热烟气的挤压像受到活塞的推挤一样流出门口;顶棚温度出现位于靠近火源和通风口连接通道所处的垂直截面附近的局...     

油罐火灾情况下管道安全性分析

为了探究输油站内泄压罐火灾对站内管道的危害,本文基于点火源模型和Pyrosim软件对距离泄压管中心10 m、15 m、20 m处的管道进行了升温计算分析。结果表明:(1)距离火源越近,空气换热对管道升温更加明显,空气换热随着管道温度上升更加剧烈;(2)Pyrosim软件在网格化上的计算比理论计算更有优势,计算结果明显放大,保守程度更高。     

冬期施工防火不容忽视

冬期施工是火灾多发季节。失火原因是：①易燃易爆物品较多。大量的木质材料、油漆、香蕉水及其它易燃建筑材料因储存不当而起火；②动火制度不严，明火作业点多。施工现场气焊设备少者几台，多者十几台同时作业，电火花温度高，电弧高达６０００℃；熬制沥青温度也较高。这些火源如果控制不严，稍有不慎便会引起木材、草袋等易燃物起火；③机械、电器设备较多，用电量大，电气设备不符合防火要求，乱拖乱拉乱接临时线路，极易发生电火；④工棚简陋，且大多使用木料、苇席、竹架板等易燃物临时搭设，加之施工人员复杂，缺乏消防知识，随意吸…     

北京北四环一车非法花炮发生爆炸

2013年1月1日下午，北京市北四环一辆运输烟花爆竹的金杯车突然自燃起火，车上10余箱烟花爆竹发生爆炸。经查，车主所载的花炮均为非法烟花爆竹。据悉，当日13时30分许，司机于某驾驶一辆金杯车行驶至朝阳区北四环亚运村附近时车辆自燃起火，将车上运输的10余箱烟花爆竹引燃发生爆炸。所幸司机及时弃车，未发生人员伤亡。事故发生后，经警方调查，2012年12月31日，于某自河北省三河市某路边商贩处非法购买10余箱非法烟花爆竹，打算在元旦期间向关系户送礼。事发当天，于某正打算将所购的非法烟花爆竹送往海淀某位关系户，行至北四环亚运村附近因车辆自燃引起烟花爆竹爆炸。     

风机功率对火灾温度场影响的数值模拟

研究危险化学品生产作业场所的风机功率对火灾温度场影响的变化特性,使用FDS模拟计算软件PyroSim,对真实环境下火灾发生、发展过程进行数值模拟。以物质的化学性质为依据,计算火源功率,对0、1.5、3.0、6.0、9.0、12.0 kW等6种不同风机功率下的火灾发生过程进行模拟计算。研究结果表明:风机在火灾规模较小时作用有限,在较大火灾发生时影响很大。大功率风机对火源周围,尤其是火源下风向处的温度场和热流密度有很大影响,并且大功率风机能够较好地控制火源周围的温度,防止热流密度过大对周围的人和物造成损害。     

江苏南京一石化炼油厂爆炸起火未对大气造成较大影晌

2014年6月9日12时30分，位于江苏省南京市六合区的一石化炼油厂硫回收装置一酸性水罐发生爆炸起火，引燃旁边的罐子，当天16时20分大火被扑灭。然而，因为火情比较复杂，罐体温度较高，18时多，罐内可燃物复燃。据了解，9日最先爆炸燃烧的是6号罐，后来延及旁边的7号罐和8号罐，当晚又引燃了旁边的2号罐，并持续在燃烧。     

一种模拟气液相变过程的相变模型

提出了一种基于VOF（volume of fluid）方法的相变模型，用于计算气液相变过程的控制方程中的传热传质源项。在单位时间步长上相界面附近发生的传热以瞬态热扩散来考虑，并假设该传热导致了相变的发生。相变模型能够通过相界面单元的温度、流体热物性以及时间步长来计算传热传质源项。通过一维Stefan问题和二维水平膜沸腾问题对该相变模型进行验证，对比了相界面位置以及温度分布，结果与理论解吻合良好。进一步探讨了相变模型中的时间步长对计算精度的影响。结果表明时间步长越小，本相变模型模拟得到的结果与理论解的偏差越小。     

塑料注射机虚拟仿真系统的动画研究

采用ProE Plastic Advisor软件研究了塑料注射机虚拟仿真系统,对汽车悬架垫片注塑工艺参数的仿真研究得到了不同注射工艺参数的动画。仿真结果表明:汽车悬架垫片的最佳浇口位置位于零件中心。选取最佳浇口位置为注射位置,汽车悬架垫片的总注射时间为1.24 s,最大注射压力为40.32 MPa,最大注射温度和最小注射温度分别为240℃和239.62℃。冷却过程中,注射位置附近的温差最大,高于平均温度2.92℃;距离注射位置最远的位置温差最小,低于平均温度1.67℃。基于注射机虚拟仿真系统,分析了熔体温度和模具温度对塑料注射过程的影响。结果表明,注射压力和注射时间都随着熔体温度的增加而减小,注射时间随着模具温度的增加而增大,而注射压力随着模具温度的增加而减小。     

耐热难燃输送带的研制

<正>在输送水泥熟料、烧结矿石、焦炭等高温固体物料的场合,经过处理,大部分物料温度能降到200℃甚至150℃以下,但仍有一小部分物料温度达到500℃~1000℃。这部分物料会烧穿输送带工作面覆盖胶直至骨架层,降低输送带使用寿命,带明火的物料还会引燃输送带,引发火灾。在这些场合使用既耐热又有阻燃性的输送带可避免安全事故。本文介绍了耐热难燃输送带的研制,骨架材料使用DSNN或DSEP帆布;在覆盖胶中使用阻燃剂     

An experimental investigation on char pattern and depth at postflashover compartments using medium‐density fibreboard (MDF)

To determine the fire origins for postflashover compartments, the char pattern and depth are investigated. A set of experiments was carried out using large‐scale compartments made of medium‐density fibreboard. A liquefied petroleum gas burner was used as the ignition source to mimic the fire origin. The burner was set at different locations in different experiments. It is found that time to flashover, intermittent flame of gas burner and ventilation condition have effects on the char patterns. The ‘ventilation patterns’ are likely to confuse the fire investigators; therefore, it needs to be identified from the ‘flame patterns’. In general, the ventilation patterns at the floor would initiate directly from the compartment opening. CFD simulations is used to reflect the ventilation conditions during fires thus assisting the identification of ventilation patterns. For those cases with less distinguishable char patterns, the profiles of total leftover material thickness and char depth were used to determine the fire origin. The char layer and total thickness in the flame regions were found to be respectively deeper and thinner than the rest parts of the compartment. The ventilation condition also affects the char depth profile; therefore, it cannot be ignored from analysis. At the end, a strategy of fire origin determination is proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

Prediction of time to ignition in multiple vehicle fire spread experiments

This paper describes the application of the flux‐time product ignition criterion and the point source flame radiation model to predict the time to ignition in multiple vehicle spread scenarios. Ten experiments from the literature have been selected due to sufficiency of information required to apply the methods. The outcome of this work is to be applied to a risk‐based model for the design of car parking buildings to determine when and if a fire spreads between vehicles; therefore, the analysis suggests properties of a representative material that can reasonably account for those external vehicle components that are most likely to ignite first. The application of both methods to the complex problem of multiple vehicle ignition requires several assumptions and simplifications which are discussed in the paper.     

Reconstruction of Grenfell Tower fire. Part 2: A numerical investigation of the fire propagation and behaviour from the initial apartment to the façade

The dramatic event of the Grenfell Tower in 2017 reminds the importance of addressing fire issues as a whole and clearly highlighted one of the major roles played by the façade as fire propagation vector. To understand and analyse this disaster, numerical simulation allows particular phenomena to be evaluated more easily. The numerical model addressed for the fire behaviour of the façade system was developed using a multiscale approach and validated at different scales. In this paper, the fire behaviour of the façade and of its window frames is addressed. A computational fluid dynamics (CFD) model is used to investigate the fire spread from the initial apartment to the overall façade with different scenarios for the fire source and ventilation. Fire propagation through windows to the façade and to upper apartments is addressed. General curves representing the re-entry of flames into upper apartment are extracted from simulations. The numerical results are validated by comparison with observations from videos and pictures of the real fire. Numerical results show that whatever the initial fire location and ventilation conditions, even if the fire source is of hundreds kilowatts, it is enough to ignite the adjacent element early and to the appearance of external flames shortly after.     

Highway vehicle fire data based on the experiences of US fire departments

In 2003–2007, US fire departments responded to an average of 267 600 highway vehicle fires per year. These fires caused an average of 441 civilian deaths, 1326 civilian injuries, and $1.0bn (in US dollars) in direct property damage annually. Highway vehicles include cars, trucks, and other vehicles designed for highway use; highway vehicle fires can occur anywhere, not just on a highway. While these fires and associated losses have been falling in recent years, highway vehicles fires accounted for 17% of reported US fires, 12% of US fire deaths, 8% of US civilian fire injuries, and 9% of the direct property damage from reported fires. Data from the US Fire Administration's National Fire Incident Reporting System and the National Fire Protection Association's fire department survey were used to provide details about the circumstances of highway vehicle fires. Mechanical or electrical failures caused roughly three‐quarters of the highway vehicle fires but only 11% of the deaths. Collisions and overturns were factors contributing to the ignition in only 3% of the fires, but fires resulting from these incidents caused 58% of these vehicle fire deaths. The rate of bus fires per billion miles driven was 3.5 times that for highway vehicle fires overall. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental and numerical investigation of fire development in a real fire in a five‐storey apartment building

A fire in a five‐storey apartment building was investigated experimentally and numerically. The room of origin of the fire was a living room in the second floor and the fire was started by a candle on a television set. The fire spread externally over the building faccade and internally along the staircase and affected all the flats above leading to two fatalities. It is estimated that the fire was discovered minutes after ignition and the fire service was called very shortly after the detection and was at the scene 9 min after the call. By this time large sections of the façade were on fire already. The rapid fire that spread over the façade and the staircase necessitated detailed investigations. Compliance of building products with the building regulations was investigated. One conclusion of the investigations was that the person who caused the fire by leaving the candle on the TV set unattended should not be held responsible for the two fatalities in the upper floors. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of modern plastic furniture on the fire development in fires in homes: large‐scale fire tests in living rooms

About 80% of all fire fatalities in Germany occur because of fires in homes. It has been known for some time that modern materials (synonym for materials consisting mostly of synthetic polymers) tend to burn differently from older materials (synonym for materials consisting mostly of fibrous cellulosic substances) and it has been acknowledged that the amount of combustible plastics in homes has increased significantly over the last decades. To investigate the influence of modern furniture and ventilation conditions of fires in homes, a series of four large‐scale tests in two living rooms (LRs) with adjacent rooms (ARs) was performed by BAM and the Frankfurt fire service. Two LRs, one with older furniture and one with modern furniture, were tested twice each. Each test started with the ignition of a paper cushion on an upholstered chair. The influence of modern materials on the fire development was investigated, as well as the influence of the ventilation on the fire development. In all settings, an upholstered chair was the first burning item. Results of the test series show that fires in rooms with modern furniture develop faster than fires in rooms with older furniture. This is true for temperature development in the rooms as well as for smoke production.     

A numerical study on the effects of naturally ventilated shaft and fire locations in urban tunnels

In more and more tunnels, natural ventilation mode with vertical shafts has been gradually employed. However, there are few studies investigating the influences of fire and shaft positions on natural ventilation performance currently. Therefore, this study investigated the effects of the transverse distance from fire source to tunnel sidewall, the longitudinal distance from fire source to shaft, and the transverse distance from shaft to sidewall on natural ventilation effectiveness in a tunnel fire by using Fire Dynamics Simulator. The typical characteristic parameters of smoke, such as mass flow rate, temperature distribution, and velocity vector were analyzed; besides, the phenomenon of plug‐holing was discussed. The results have shown that the mass flow rate of gas exhausted by the shaft decreases slightly with the increase of longitudinal distance from fire source to shaft. When the longitudinal distance from fire source to shaft is constant, changing the transverse distance from shaft to sidewall will have a more obvious effect on the effectiveness of exhausting smoke than changing the transverse distance from fire source to sidewall; in addition, the phenomenon of plug‐holing is more serious when the shaft is close to the sidewall.     

Detailed analysis of a smouldering fire scenario at the murder scene experimental and numerical investigations

Based on forensic evidence, a smouldering fire was observed to have occurred at a murder scene. Identification of a reasonable timeline – specifically the fire dynamics of the ignition and fire growth that occurred coincident with the death that took place – became an important focus of the criminal investigation that followed. The fire service was called when a neighbour saw a grey smoke escaping through the ventilation system of the bathrooms on the roof of the house. One flat door with elevated temperatures was found. The fire fighter who entered the flat first reported later that the flat was completely filled with smoke and all windows were closed. When the fire fighter opened the balcony door, he saw flames on the sofa that he extinguished. Then he found a body on the floor. The autopsy showed later that the victim was dead before the fire started. The police suspected that the murderer probably had deliberately set the fire to destroy evidence. One suspect had been witnessed to be in the flat approximately 2 h before the fire was detected by the neighbour. The aim of this project was to investigate how the fire most likely started and developed. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimental and numerical simulation studies on diesel pool fire

Experimental studies are performed under different ventilation conditions to investigate the effect of ventilation on compartment fires. A compartment of size 4 m × 4 m × 4 m having a door of size 2 m × 1 m is used for experiments. The experiments are conducted with full door open and half door open conditions. Diesel, used as a fuel source, is placed in a pan of 40 cm diameter and 15 cm height, which is kept in the center of the compartment. During experiments a constant 12 cm height of the fuel is maintained above the pan bottom. The maximum heat release rate is found to be 100 kW and 115 kW in full door open and half door open experiments respectively. It is observed that the size of door opening affected the heat release rate, burning rate and thermal environment inside the compartment after the growth period of 800 s. The numerical simulation is also performed for full door open experiment using CFD code, Fire Dynamics Simulator (FDS, version 6.0.1) developed by NIST. Simulation is accomplished with the refinement of mesh size near the fire source; results from FDS closely match with the experimental results. Copyright © 2016 John Wiley & Sons, Ltd.     

Assessment of fire behaviour of high‐speed trains' interior materials: small‐scale and full‐scale fire tests

The development of fire‐safety measures for high‐speed passenger trains has been focused on preventing fire initiation or delaying fire growth and spread through small‐scale tests of the materials used in trains. However, new fire‐safety approaches for trains consider a systemic approach. This approach considers numerous global factors that influence fire dynamics, such as the influence of vehicle design, selection of materials, and active and passive protection systems installed. In the present paper, the results of small‐scale and full‐scale tests carried out on the new generation of high‐speed trains operating in Spain are presented. This rolling stock is classified as category B according to the Technical Specification for Interoperability and Operation Category 3 according to EN 45545–1. The results confirmed good fire behaviour using both approaches (small and full‐scale tests). Additionally, several analyses have been performed, including an analysis of the quality of materials used for making different components of the passenger compartment and the influence of ignition source position on fire development. Copyright © 2013 John Wiley & Sons, Ltd.