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Study on the plume flow behavior and air entrainment characteristics of co-burning fires 共燃火灾的烟流行为和空气夹带特性研究
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-09 DOI: 10.1016/j.firesaf.2024.104211
Qineng Zhou, Chen Wang, Haowei Hu, Weixin Tong, Jingbo Xu, Jie Ji

In most of the fire accidents, there is large oil layer leaking into the fire dike and multiple fire points burning simultaneously. A series of numerical simulations for co-burning of a dike and double tanks (co-burning) with different spacing S have been conducted to study the plume flow behavior and air entrainment characteristics. The simulation results show that there is a conical fuel-rich region on the upper rim of the tank which results in the entrained air to flow circularly along the surface of the conical region. With the increase of S, the restriction effect of tank sidewall on air entrainment from environment enhances, while the restriction degree of air entrainment in the middle area of the double tanks decreases, affecting the distribution of plume velocity field and temperature field. And under the coupling effect of them, the tilt degree of tank flame decreases with the increase of S (from 0.3 m to 0.7 m). The air entrainment restriction coefficient αB, αS are introduced to characterize the restriction effect of air entrainment between the external dike fire and the double tank fires. Based on this, a co-burning plume entrainment model has been established, which can be applicable to different spacing S.

在大多数火灾事故中,都会有大量油层渗漏到防火堤中,并有多个着火点同时燃烧。我们对不同间距 S 的堤坝和双油罐(共同燃烧)进行了一系列数值模拟,以研究烟流行为和空气夹带特性。模拟结果表明,罐体上缘存在一个锥形富燃料区,导致夹带的空气沿锥形区表面环流。随着 S 的增大,油箱侧壁对环境夹带空气的限制作用增强,而双层油箱中间区域对夹带空气的限制程度减小,从而影响烟流速度场和温度场的分布。在二者的耦合作用下,随着 S 的增大(从 0.3 米到 0.7 米),水箱火焰的倾斜度减小。引入空气夹带限制系数 αB、αS 来表征外堤火与双罐火之间的空气夹带限制效应。在此基础上,建立了可适用于不同间距 S 的共燃烟羽夹带模型。
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引用次数: 0
Corrigendum to “Simulation of a premixed explosion of gas vented during Li-ion battery failure” [Fire Saf. J. 126 (2021) 103478] 对 "模拟锂离子电池故障时排出气体的预混合爆炸 "的更正 [Fire Saf. J. 126 (2021) 103478]
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-06 DOI: 10.1016/j.firesaf.2024.104208
Mathias Henriksen , Knut Vaagsaether , Joachim Lundberg , Sissel Forseth , Dag Bjerketvedt
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引用次数: 0
Effect of the Al/Si ratio on intumescent Na-based geopolymer 铝/硅比对膨胀型 Na 基土工聚合物的影响
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-04 DOI: 10.1016/j.firesaf.2024.104220
Qi Yang , Catherine A. Davy , Johan Sarazin , Serge Bourbigot , Gaëlle Fontaine

This research investigates the fire resistance properties of alkali activated Na-based geopolymers (GP), used as steel protective coatings. The effect of different Al/Si molar ratios (0–0.54) is evaluated fire test. When coated on a steel plate, GP having the smaller Al/Si ratio exhibits an intumescent behavior with the highest expansion. When Al/Si = 0, the temperature at the backside of the steel plate is 313 °C which is decreased by 347 °C compared to an uncoated steel plate (660 °C). After fire testing, the GP physico-chemical properties are characterized with optical microscopy, Electron probe micro-analysis, dynamic mechanical analysis. According to stiffness test results, when the temperature approaches 100 °C, the GP with a given Al/Si ratio (different from zero) softens and expands (intumescence). The greater the Al/Si ratio in the GP, the more rigid the structure; this phenomenon limits expansion, and hence, lowers the fire protection.

本研究调查了用作钢铁保护涂层的碱活化 Na 基土工聚合物 (GP) 的耐火性能。在火灾试验中评估了不同铝/硅摩尔比(0-0.54)的影响。在钢板上涂覆时,铝/硅比率较小的 GP 表现出膨胀性最高的膨胀行为。当 Al/Si = 0 时,钢板背面的温度为 313 °C,与未涂层钢板(660 °C)相比降低了 347 °C。火灾测试后,使用光学显微镜、电子探针显微分析和动态机械分析对 GP 的物理化学特性进行了表征。根据刚度测试结果,当温度接近 100 ℃ 时,特定铝/硅比(不同于零)的 GP 会变软并膨胀(膨胀)。GP 中的铝/硅比越大,结构就越坚硬;这种现象限制了膨胀,从而降低了防火性能。
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引用次数: 0
Large-scale fire experiments in a cross-laminated timber compartment with an adjacent corridor – Partly and fully protected with a water sprinkler system 在带邻近走廊的交叉层压木隔间内进行大规模火灾实验 - 部分和全部采用水喷淋管道系统进行保护
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-03 DOI: 10.1016/j.firesaf.2024.104212
Andreas Sæter Bøe , Kristian Hox , Ragni Fjellgaard Mikalsen , Kathinka L. Friquin

Two fire experiments have been conducted to study sprinkler system extinguishing performance in a compartment (13 m2) with an adjacent corridor (12 m2), both with exposed cross-laminated timber (CLT). Four nozzles were installed in the corridor and two in the compartment. In Experiment 1, the sprinkler system was fully functional and successfully controlled a concealed fire. In Experiment 2, nozzles in the compartment were disconnected, while the corridor nozzles were operative, giving flashover after 5 min with large flames emerging into the corridor, rapidly worsening evacuation conditions. Despite four activated nozzles in the corridor, the temperatures remained high, and flames spread through the corridor along the CLT ceiling and the upper parts of the wall, an area that was not effectively protected by the nozzles. After flashover, the compartment temperatures remained stable at ∼1000 °C until experiment termination at 96 min. This continued fire in the compartment can be explained by water from the corridor sprinklers not reaching this area, extensive radiative feedback by the CLT surfaces and delamination of CLT elements of the 20 mm layers. The charring rate was ≥1.1 mm/min for large parts of the exposed CLT wall and ceiling in the compartment during the fire.

为了研究喷水灭火系统的灭火性能,我们进行了两次火灾试验,试验地点是一个隔间(13 米)和一个相邻的走廊(12 米),这两个隔间都有裸露的交叉层压木材(CLT)。走廊安装了四个喷嘴,隔间安装了两个喷嘴。在实验 1 中,自动喷水灭火系统功能齐全,成功控制了一场隐蔽火灾。在实验 2 中,隔间中的喷头断开,而走廊中的喷头正常工作,5 分钟后出现闪燃,大面积火焰涌入走廊,迅速恶化了疏散条件。尽管走廊的四个喷嘴都已启动,但温度仍然很高,火焰沿着 CLT 天花板和墙壁上部(喷嘴无法有效保护的区域)蔓延到走廊。闪燃后,隔间温度稳定在 1000 °C,直到 96 分钟实验结束。车厢内持续起火的原因可能是走廊喷淋器的水没有喷到这一区域、CLT 表面产生大量辐射反馈以及 20 毫米层的 CLT 元件脱层。火灾期间,隔间中大部分暴露在外的 CLT 墙壁和天花板的炭化速度≥1.1 毫米/分钟。
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引用次数: 0
Influence of upstream blockage on smoke control in tunnel fires 上游堵塞对隧道火灾烟雾控制的影响
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-01 DOI: 10.1016/j.firesaf.2024.104197
Ying Zhen Li, Haukur Ingason

Smoke control in a longitudinally ventilated tunnel with various blockage conditions was investigated experimentally. A total of 28 tests were conducted with a focus on single blockage with a short distance from the fire source, although continuous blockage and semicontinuous blockage were also discussed. Both gas and pool fires were used. The aim was to understand the influence of upstream blockage on critical velocity and babcklayering length. The results confirm that blockage ratio is a critical parameter when determining the critical velocity and backlayering length. The longitudinal location of the blockage in relation to the fire source also influences the values of critical velocity and backlayering length. The experiments presented are in scale 1 to 3.3, representing a medium sized tunnel. The focus was on free flow conditions and blockage ratios of regular sizes. For the various tested scenarios with single blockage, the reduction ratio of critical velocity appears to be slightly less than the blockage ratio. However, when the blockage is attached to the upstream side of the fire source, the reduction ratio of critical velocity approximately equals the blockage ratio.

实验研究了各种堵塞条件下纵向通风隧道的烟雾控制情况。共进行了 28 次测试,重点是与火源距离较近的单一阻塞,但也讨论了连续阻塞和半连续阻塞。试验中使用了气火和池火。目的是了解上游堵塞对临界速度和 babcklayering 长度的影响。结果证实,在确定临界速度和背层长度时,阻塞率是一个关键参数。堵塞物相对于火源的纵向位置也会影响临界速度和背压长度的值。所展示的实验规模为 1 到 3.3,代表了一个中等规模的隧道。重点是自由流动条件和规则尺寸的堵塞率。在单个堵塞物的各种测试方案中,临界速度的降低率似乎略低于堵塞率。然而,当堵塞物附着在火源的上游侧时,临界速度的降低率近似等于堵塞率。
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引用次数: 0
Shrinkage characteristics of glass and mineral fibre insulation materials at elevated temperatures 玻璃纤维和矿物纤维绝缘材料在高温下的收缩特性
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-07-01 DOI: 10.1016/j.firesaf.2024.104210
Linbo Zhang, Mohamed A. Sultan

The fire resistance of building assemblies can be determined through testing or by numerical modelling. As testing of building assemblies is expensive and time-consuming, the development of numerical modelling methods is gaining momentum. One of the challenges in modelling assemblies’ thermal performance is insulation dimensional shrinkage at elevated temperatures. To address this challenge, this paper presents a comprehensive experimental investigation into the shrinkage of glass and mineral fibre insulation materials under elevated temperature conditions. Initially, a series of tests was conducted to establish the temperature range within which significant shrinkage occurs for both types of insulation. Then, visual observations and measurements were recorded to assess the physical and dimensional changes of the insulation materials within the identified temperature range for shrinkage, indicating distinct responses of glass and mineral fibre insulation to thermal exposure. Compared to width and length variations, thickness reduction in insulation was more significant. Overall, the insulation thickness decreased as the exposed temperature increased. The glass fibre insulation completely melted at 710 °C, while mineral fibre insulation disintegrated at 1000 °C. In addition, empirical equations were derived to assess the thickness variations of these insulations at elevated temperatures, which can greatly enhance the accuracy of future thermal models under fire scenarios. Lastly, potential areas for future research are identified.

建筑组件的耐火性能可以通过测试或数值模拟来确定。由于对建筑组件进行测试既昂贵又耗时,因此数值建模方法的发展势头日益强劲。模拟装配式建筑热性能的挑战之一是保温材料在高温下的尺寸收缩。为了应对这一挑战,本文对玻璃纤维和矿物纤维保温材料在高温条件下的收缩情况进行了全面的实验研究。首先,进行了一系列测试,以确定两种隔热材料发生明显收缩的温度范围。然后,通过目视观察和测量记录,评估绝缘材料在确定的收缩温度范围内的物理和尺寸变化,结果表明玻璃纤维和矿物纤维绝缘材料对热暴露的反应截然不同。与宽度和长度变化相比,隔热材料厚度的减少更为显著。总体而言,隔热材料的厚度随着暴露温度的升高而减小。玻璃纤维隔热材料在 710°C 时完全熔化,而矿物纤维隔热材料在 1000°C 时解体。此外,还得出了经验方程来评估这些隔热材料在高温下的厚度变化,这可以大大提高未来火灾情况下热模型的准确性。最后,确定了未来研究的潜在领域。
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引用次数: 0
Operational uptime and other measures of performance of an open car park in fire 消防开放式停车场的正常运行时间和其他性能指标
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-06-28 DOI: 10.1016/j.firesaf.2024.104209
Wojciech Węgrzyński, Paulina Jamińska-Gadomska, Bartosz Miechówka, Grzegorz Krajewski

192 coupled wind and fire CFD simulations were performed using ANSYS Fluent to study the wind and fire interaction in an open car park. The natural ventilation was insufficient for removal of smoke and heat for the majority of investigated fires. Blockage effect was observed for wind directions parallel to the open walls, which resulted in reduced smoke removal and higher smoke temperatures. With known probabilities of all the investigated wind speed and directions, we have estimated the percentage of time in which fire outcomes are acceptable. This value was coined as the car park operational uptime, and was 84.9 %–92.8 % in relation to the fire with HRR = 1.4 MW; 36.5 %–56.1 % at 4.0 MW; 34.1 %–54.4 % at 6.0 MW and 12.13–25.5 % at 8.8 MW. In 6.22 % of wind cases, the velocity inside the car park exceeded 3.0 m/s, which could potentially contribute to the growth of the fire. Limitations of the study include the assumed wind probability distribution relevant to the Warsaw region, the single location of the fire used in the assessment and the implicit modelling of topography and architecture through an introduced wind profile and terrain roughness model.

使用 ANSYS Fluent 进行了 192 次风与火 CFD 耦合模拟,以研究开放式停车场中风与火的相互作用。在大多数调查的火灾中,自然通风不足以消除烟雾和热量。与开放式墙壁平行的风向会产生阻塞效应,导致排烟量减少和烟雾温度升高。根据所有调查风速和风向的已知概率,我们估算出火灾结果可接受的时间百分比。该值被称为停车场运行正常时间,在 HRR = 1.4 MW 的情况下为 84.9 %-92.8 %;在 4.0 MW 的情况下为 36.5 %-56.1 %;在 6.0 MW 的情况下为 34.1 %-54.4 %;在 8.8 MW 的情况下为 12.13-25.5 %。在 6.22% 的风力情况下,停车场内的风速超过了 3.0 米/秒,这有可能导致火势蔓延。该研究的局限性包括:假定的风力概率分布与华沙地区相关、评估中使用的火灾地点单一以及通过引入风廓线和地形粗糙度模型对地形和建筑进行隐式建模。
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引用次数: 0
On the Nusselt number correlations of tandem surrogate firebrands on a flat surface 关于平面上串联替代火带的努塞尔特数相关性
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-06-28 DOI: 10.1016/j.firesaf.2024.104207
Savannah S. Wessies, Jiann C. Yang

Through the heat-mass transfer analogy, naphthalene sublimation experiments were conducted in a heated-air wind tunnel to study the effects of aspect ratio and dimensionless separation distance on the convective heat transfer coefficients of three tandem naphthalene cylinders. Nusselt number correlations were presented for the individual naphthalene cylinders and the full configuration of three cylinders. In all the cases studied, the Reynolds number had the strongest effect on the Nusselt number followed by the aspect ratio and the dimensionless separation distance. Nusselt numbers were higher for the smaller aspect ratios. For a given Reynolds number and aspect ratio, the Nusselt number increases with the dimensionless separation distance.

通过热质传递类比,在加热空气风洞中进行了萘升华实验,研究了高宽比和无量纲分离距离对三个串联萘圆柱体对流传热系数的影响。研究给出了单个萘气缸和三个气缸完整配置的努塞尔特数相关性。在所有研究案例中,雷诺数对努塞尔特数的影响最大,其次是长宽比和无量纲分离距离。纵横比越小,努塞尔特数越高。对于给定的雷诺数和纵横比,努塞尔特数随无量纲分离距离的增加而增加。
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引用次数: 0
Synergistic effects of typical clean gaseous fire-extinguishing agents 典型清洁气体灭火剂的协同效应
IF 3.4 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-06-18 DOI: 10.1016/j.firesaf.2024.104206
Qichang Dong, Jiacheng Qi, Song Lu, Long Shi

Gaseous fire-extinguishing agents have received widespread attention due to their high efficiency, excellent extinguishing performance, and limited damage to protected objects. Previous attempts have mainly focused on the fire-extinguishing effect of single gaseous fire-extinguishing agents, where the synergistic use of gaseous extinguishing agents with different extinguishing agents has been less summarized. This study critically reviewed typical gaseous fire-extinguishing agents and their synergistic extinguishing effects, including Novec1230, hydrofluorocarbons (HFCs), inert or inactive gases, etc. It was known that the synergistic use of different extinguishing agents could compensate for the shortcomings of a single agent in physical or chemical fire extinguishing, reduce the amount of extinguishing agent used, the production of toxic substances, and improve the efficiency of the mixed system of fire extinguishing. Gas-gas synergy (e.g., Novec1230-C6F15N or Novec1230-CO2) can inhibit the flammability of some gaseous extinguishing agents at low concentrations and enhance the flame retardant and explosion suppressant effects of the mixed systems. Gas-liquid synergy (e.g., Novec1230-water mist or HFC-227ea-water mist) considers both the roles of rapid fire suppression and cooling of the protection object. To a certain extent, gas-solid synergy (e.g., HFC-227ea-SiO2 dry powder or N2-ABC dry powder) makes up for the poor coverage of dry powder fire extinguishing agents to achieve rapid and low-pollution fire extinguishing goals. This review offers guidance and suggestions for the efficient and clean use of extinguishing agents and the potential future direction.

气体灭火剂因其灭火效率高、灭火性能优越、对被保护对象的损害有限而受到广泛关注。以往的尝试主要集中在单一气体灭火剂的灭火效果上,对气体灭火剂与不同灭火剂的协同使用总结较少。本研究对典型的气体灭火剂及其协同灭火效果进行了严格审查,包括 Novec1230、氢氟碳化合物(HFCs)、惰性或非活性气体等。众所周知,不同灭火剂的协同使用可以弥补单一灭火剂在物理或化学灭火中的不足,减少灭火剂的使用量和有毒物质的产生,提高混合系统的灭火效率。气-气协同(如 Novec1230-C6F15N 或 Novec1230-CO2)可抑制某些气态灭火剂在低浓度下的可燃性,增强混合体系的阻燃和抑爆效果。气液协同(如 Novec1230-水雾或 HFC-227ea-水雾)兼顾了快速灭火和冷却保护对象的作用。气固协同(如 HFC-227ea-SiO2 干粉或 N2-ABC 干粉)在一定程度上弥补了干粉灭火剂覆盖面小的缺陷,达到快速、低污染灭火的目的。本综述为高效、清洁地使用灭火剂以及潜在的未来方向提供了指导和建议。
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引用次数: 0
Analytical formulations with experimental validation for determining the incident heat flux from firefronts 通过实验验证确定火面入射热通量的分析公式
IF 3.1 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2024-06-12 DOI: 10.1016/j.firesaf.2024.104205
MohammadReza Modarres , Miguel Almeida , Gilberto Vaz , Domingos X. Viegas

Any target exposed to a heat source receives a certain amount of heat flux, depending on the distance, view factor, characteristics of the source, and environmental properties. Incident heat flux is mainly characterized by firefront properties, e.g., flame dimensions, and its thermal attributes by fuel properties, topography, and meteorological factors. Predicting the incident heat flux from the firefronts is crucial for fire risk management and analytical and numerical fire modelling. Based on this specification, safe zones can be defined for elements such as unprotected individuals, firefighters, and buildings. Since the contribution of radiation and convection varies with the fire evolution, it is essential to specify them as a function of distance and slope. This study elaborates determination of radiation and convection for firefronts. Sets of laboratory-scale experiments were conducted using fuel beds of straw with a load of 1.5 kg/m2 on the slopes of 0°, 20°, and 40° measuring the incident radiative and total heat fluxes. The proposed methodology was validated using available approaches and correlations between the flame length and the acceptable safety distance (ASD) were established. Unlike the existing models, a nonlinear correlation between convection and radiation during the firefront evolution is proposed.

任何暴露在热源下的目标都会接收到一定量的热通量,这取决于距离、视角系数、热源特性和环境属性。入射热通量主要由火面特性(如火焰尺寸)以及燃料特性、地形和气象因素决定的热属性来表征。预测来自火面的入射热通量对于火灾风险管理以及火灾分析和数值建模至关重要。根据这一规范,可以为无保护人员、消防员和建筑物等要素定义安全区域。由于辐射和对流的作用随火灾演变而变化,因此必须将它们指定为距离和坡度的函数。本研究详细阐述了火场辐射和对流的确定方法。在 0°、20° 和 40° 坡度上使用负载为 1.5 kg/m2 的稻草燃料床进行了多组实验室规模的实验,测量入射辐射和总热流量。利用现有方法对所提出的方法进行了验证,并建立了火焰长度与可接受安全距离(ASD)之间的相关性。与现有模型不同的是,提出了火线演变过程中对流与辐射之间的非线性关联。
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引用次数: 0
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Fire Safety Journal
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