Benchmarking the Single Item Ignition Prediction Capability of B-RISK Using Furniture Calorimeter and Room-Size Experiments

This paper benchmarks B-RISK’s capability to predict item ignition in multiple object compartment fire simulations. A series of fire experiments have been conducted which measured single item ignition times under the furniture calorimeter and in the ISO 9705 room. These experiments used mock-up armchair, TV and cabinetry furniture items created from three common materials found in most households in New Zealand exposed to a 100 kW gas burner flame. B-RISK uses the flux-time product (FTP) method as the criterion to predict ignition of items, based on radiation received using the point source model (PSM). This paper presents an analysis of the B-RISK predictions compared to the experimental measurements. Due to the mathematical formulation of the PSM and FTP method, it is found that the predicted ignition time is sensitive to the distance between the radiative source and the item. Predicted ignition times of armchairs constructed of polyurethane foam were within 14% of the ISO 9705 room experimental results. However, for the furniture calorimeter experiments it is found that to get reasonable predictions of the ignition times for the mock-up armchair and TV items there is a need to account for the burner flame movement by adjusting the radial distance by 10–30 mm. Direct flame contact was required to ignite the mock-up cabinetry items and B-RISK was unable to successfully predict this ignition time.     

布料机布料臂架有限元建模与仿真研究

以国内首次研制成功的40 m大跨距布料机臂架结构为研究对象,采用参数化建模APDL方法和多单元连接技术,基于ANSYS软件平台实现复杂布料臂架系统的精确建模和拟实加载.根据各构件的结构特征、连接形式与承载特性,将布料臂架抽象成由杆、梁、板、壳、质量、弹簧及阻尼等力学要素,不同的力素对应不同的分析单元类型,不同的单元经连接后共同构成复杂空间刚架模型.参照相关设计规范和使用工况,结合多体动力学系统模拟结论,布料机最危险工况组合为:布料机前倾某角度放置、臂架呈全伸展状态、臂架位于某仰角、高位按最大受风面积承风(6级)、考虑附加动载荷等.计算考虑的主要负载有:臂架自重、皮带与托滚重、物料重、溜管及物料堆积重、风载、附加动载荷等.研究得出施加在布料臂架上的各载荷对其综合力学性能的影响情况和满负载下各臂节的变形量的分布规律,仿真表明臂架空载和满载时的最大挠度差约为0.103 m,满足大跨距布料臂架安全施工要求;输送物料重量和溜管料斗及物料堆积引起的附加重量对臂架的最大挠度和极限应力影响较缓,但对整机的抗倾覆性影响较大.     

上海消防置置上天入地“奇兵”降火魔揭秘

目前，上海有高层建筑6000多幢、地下空间3000多万平方米、轨道交通近400公裹，还有世界级的化工基地、造船基地和物流中心。这些既是城市高度繁荣的标志，也是世界性的消防安全难题。针对这些灭火救援难题，市消防局在全国率先组建了高层、地铁、化工、船舶等灭火救援专业队伍。     

Cigarette Fires Involving Upholstered Furniture in Residences: The Role that Smokers,Smoker Behavior,and Fire Standard Compliant Cigarettes Play

Residential structure fires pose a significant risk to life and property. A major source of these fires is the ignition of upholstered furniture by cigarettes. It has long been established that cigarettes and other lighted tobacco products could ignite upholstered furniture and were a leading cause of fire deaths in residences. In recent years, states have adopted fire standard compliant cigarettes (‘FSC cigarettes’) that are made with a wrapping paper that contains regularly spaced bands, which increases the likelihood of self-extinguishment. This paper measures the effectiveness of FSC cigarettes on the number of residential fires involving upholstered furniture, and the resulting fatalities, injuries, and extent of flame spread, while accounting for the under-reporting of fire incidents. In total, four models were estimated using fire department data from 2002 to 2011. The results provide evidence that FSC cigarettes, on average, reduced the number of residential fires by 45%, reduced fatalities by 23%, and extent of flame spread by 27% in 2011. No effect on injuries was found. Within each state, effectiveness is moderated by the number of smokers and their consumption patterns. In general, FSC cigarettes are more effective in places with a large smoking population who engage in heavier smoking. There is a very limited effect on the lightest of smokers, suggesting behavioral differences between heavy and light smokers that influence fire risk.     

高层建筑火灾的扑救措施

近年来,高层建筑发展十分迅速,高层建筑火灾也随之开始频繁发生,高层建筑火灾往往造成人员伤亡和巨大的经济损失。本文详细分析了高层建筑火灾的特点,并总结出相应的扑救措施。     

Pulsations During Fires in Tunnels

The existing theoretical modelling of thermoacoustic oscillations has been studied and applied to the case of tunnel fires. The assumptions of the theoretical model were reviewed. It was found that several assumptions are not applicable to tunnel fires and, hence, suggestions for improvement are given. The correlation which expresses the starting conditions for thermoacoustic oscillations is analysed and dependencies on different parameters are presented. The pulsations documented during the large-scale tests in the Runehamar tunnel in 2003 have also been further analysed. The measurements were compared to the theoretical limiting curve for oscillations, showing good agreement. To further study thermoacoustic oscillations in tunnels, more detailed tests in a model-scale tunnel (1:100) were performed. These tests focused on the circumstances which are required to create thermoacoustic oscillations, i.e. the fire was located at different positions along the tunnel and the air flow rate was varied. The tunnel had a length of 4 m, was 8 cm wide and 6 cm high. The results were in good accordance with the theoretical modelling but showed deviations which were most obvious at very low and high air velocities. Both the starting conditions for thermoacoustic oscillations and cases where the thermoacoustic oscillations suddenly stopped, were observed. These findings led to identification of several points in the theoretical model which need to be improved, and to the development of a strategy to avoid such pulsation in fires.     

Pulsation Behavior of Pool Fires in a Confined Compartment with a Horizontal Opening

This study reveals the flame pulsation behavior of pool fires in a confined compartment with a horizontal opening. A series of tests were carried out in a small-scale compartment with a central horizontal opening to obtain parameters, such as the mass loss rate (MLR), oxygen concentration, flame height, flame pulsation frequency. Results showed that the average MLR in the steady burning period varied with the opening size, whereas the oxygen concentration value at extinction remained constant for larger horizontal opening size. The mean flame height as obtained by image processing was compared with the predicted correlation for different horizontal openings. The flame pulsation frequency was obtained by performing a fast Fourier transform on the flame height. The influences of the pool fire diameter and horizontal opening size on the flame pulsation frequency were considered. The empirical correlation with exponent of ?0.5 between the pulsation frequency and diameter was verified for confined compartments, as well as the effect of the horizontal opening size on the flame pulsation frequency. In addition, the flame pulsation frequency could be characterized by a scaling relationship between the Strouhal number and Froude number.     

Typification of Fires in Buildings in Spain

Although the Dirección de General de Protección Civil (DGPC), an agency of the Spanish government, has been responsible for the collection of data and the statistical analysis of fires since 1985, it has not as yet issued any reports. It is true that a couple of studies have been made, but in neither case did they use a standardized methodology but relied simply on the heterogeneous information provided by the fire brigades which cooperated in the studies. At that time Spanish fire brigades did not have special units for professional fire investigation, nor was the information derived from standardized methodologies suited to research purposes. In addition, information was extremely scarce and basic, focussed only on the fire, the use of the building and personal data of the victims. In this context, the project for a Fire Investigation Unit in the Fire Brigade of Málaga (the sixth largest Spanish province in inhabitants) was set up. Although inspired in the methodologies used in the USA and in the UK, the aim was to create a customized methodology for the first scientific investigation of fires in Spain. Our research was conducted in 2007. Using the methodologies of the USA and the UK, our own methodological approach and the Spanish regulations, we drew up a questionnaire with 110 variables arranged into 6 modules. We studied 96 fires out of the 154 emergency fire calls received in 2007, having omitted some emergency calls for various reasons. Our results revealed that it was necessary to generalize the installation of fire extinguishers in residential buildings, to train the general public in the use of these devices, to promote the use of fire and smoke detectors in residential buildings, to encourage the inspection and control of old electric installations and to monitor the new installations, to generalize the implementation of emergency and evacuation plans and to design new systems and materials for the cabinets where hand-held extinguishers are stored.     

变差式热量表的结构设计

对一种用于计量供暖的变差式热量表的结构及主要装置、工作原理进行了研究。     

半敞开式隧道火灾通风研究

采用CFD方法运用κ-ε双方程模型对半敞开式隧道着火时烟气扩散情况进行模拟,比较不同季节时的自然通风效果.结果表明,冬夏两季时隧道采用自然通风的排烟模式是切实可行的,都能起到很好的排烟作用.火灾前期烟气扩散速度远大于火灾后期,冬季烟气水平扩散速度高于夏季,但烟气沉降冬季比夏季严重,且冬季自然排烟效率比夏季提高了3.5%;夏季隧道顶部最高温度高于冬季,且火源两侧高温区域大于冬季.     

汽车油路系统火灾分析

本文通过对辖区内近年来车辆油路火灾的原因调查,分析了导致该类火灾的几种可能因素.文中提出了从勘察汽车供油系统变化痕迹来判断油路所发生故障的勘查手段,简要得出在调查车辆火灾原因和预防车辆火灾事故的一些做法。     

Behaviour of Double Glazing in Corner Fires

The results of fifteen experiments in which a double glazing assembly was exposed to enclosure fires of increasing severity are presented. The glazing assembly was exposed to the typical two zone or one zone fire enclosure environment with consistency and repeatability within each set of three experiments conducted at each severity level, evident from the enclosure gas temperature profiles. The results presented include; enclosure local gas temperatures, local exposed glass surface temperatures, local shaded glass temperatures, total incident fluxes, convective and radiative fluxes, incident flux distributions at time of first cracking and inner and outer pane behaviours. A simple lumped model approach is developed to predict the response of the glazing to thermal insult. Total loss of glazing integrity is related graphically to the time of first crack.     

在全省建设科技重点成果技术推广发布会上的讲话

各位代表、同志们:今天在这里召开1999年度全省建设科技重点成果技术推广发布会,参加会议的有各地、市建委分管科技工作的领导,各地(市)工程质量监督站领导,各县(市、区)质量检测单位负责人 ,一、二级施工企业分管技术的领导以及应邀的技术发布单位和新闻界的朋友们.首先我代表省建委对大家的到来表示热烈的欢迎和衷心的感谢,同时预祝发布会达到预期目的,取得圆满成功.借此机会,就全省建设科技成果推广工作谈几点意见.     

高层建筑“走廊-前室缓冲区”防火效果的数值分析

在高层建筑火灾研究中,随着前室正压送风研究的深入,发现其存在着一些缺陷.于是提出在走廊段设置“走廊—前室缓冲区”的方式来改善传统正压送风模式.采用Fire DynamicSimulation(FDS)场模拟软件模拟长廊型高层建筑模型.设置8组工况进行分析,比较各种工况下烟气的温度分布,浓度分布,并通过模拟设计出最佳的参...     

Fires of insulations on tank exteriors

This paper presents a method for calculating radiative heat transfer to an adjacent tank from fire involving insulation on tank exteriors. An approximate method for calculating the radiative flux from an ignition source is also provided. The results are generalized to allow convenient estimates of safe separations for a range of tank sizes, fire intensities, and critical ignition fluxes. Wind effects are not considered in the present study.     

热量表远程抄表系统的应用

结合工程实例,论述了热量表远程抄表系统的组成、功能、特点,分析了工程建设中应注意的问题。     

Fires of insulations on tank exteriors

This paper presents a method for calculating radiative heat transfer to an adjacent tank from fire involving insulation on tank exteriors. An approximate method for calculating the radiative flux from an ignition source is also provided. The results are generalized to allow convenient estimates of safe separations for a range of tank sizes, fire intensities, and critical ignition fluxes. Wind effects are not considered in the present study. Factory Mutual Research Corporation     

Development of a Sensing Device to Reduce the Risk from Kitchen Fires

Fires originating from cooking areas are the second leading cause of fatalities and loss related to residential fires. The predominant root cause of residential stovetop cooking fires has been found to result from unattended cooking. The installation of smoke detectors can only detect and at best alert residents to a fire hazard. Control technologies for cutting gas supply to cooking devices upon receiving signals from detectors is not new. Many of stovetop mitigation technologies are currently in existence as consumer products or patents, however little evaluation has been conducted on these products in order to develop a more efficient and effective device to help reduce the frequency of cooking related fires. The paper presents a short review of literature and goes on to discuss a fire sensing device developed to act as a pre-ignition sensor that will cut off power supply to cooking devices upon receiving inputs from a detection device. The device proved to be effective when it was tested both in the laboratory and a real kitchen environment. The installation of this device, in addition to an installed detection device will play a major role in reducing the risk of most kitchen fires.