外立面空腔系统内火焰高度和传热研究

正瑞典隆德大学针对多层建筑狭窄空腔结构,通过开展试验,研究了空腔宽度对火焰高度的影响,以及火蔓延现象和辐射热通量对空腔内表面的影响。整个试验搭建2个平行不燃板材构成的空腔结构,在空腔内设置丙烷气体燃烧器。通过变换空腔宽度和改变燃烧器的热释放速率进行对比试验。研究表明,Q/W(Q为单位长度的热释放速率,W为空腔宽度)小于300 kW/m~2时,火焰高度无明显变化,当比值大于300 kW/m~2,火焰高     

地下商业街火灾热释放速率试验研究

本文通过研究测定燃料质量损失速率和出口的烟气流速,建立小火荷试验的火灾热释放速率与烟气生成量的关系,从而获得实体火灾试验中的地下商业街火灾热释放速率（Heat Release Rate）数据和烟气质量流量数据。     

纵向通风隧道内火灾烟气流动的控制

讨论了纵向通风隧道火灾和相关烟气形成现象。利用计算机流体动力模型模拟烟气流动，获得可以与试验数据进行比较的预测结果。在Richardson数字基础上，采用了不同参考稳定值，结果发现，直接利用火灾热释放速率所获得的温度值会产生最有用的结果。试验结果与数值预测结果的比较发现，两者吻合较好。笔者验证了利用容积测定火源模拟火灾的情况。结果的准确性很大程度上取决于对墙和屋顶的热传递。     

地铁站内烟气流动特性和消防安全

介绍了地铁站内烟气流动和控制的试验和数值研究。在三个真正地铁站内利用甲醇油池火作为燃料进行了试验，用所获得数据来验证地铁站火灾数值模型，并进一步检验其烟控系统的性能。在站内使用了制量烟气流动模型，再现了最简单条件下每个站点的试验结果，然后把结果跟其他试验条件下的试验结果进行了比较。最后，用模型预测更复杂火灾的烟气流动情况。另外，还讨论了地铁系统的有效设计和火灾安全设施的正常运作情况。通过限制内饰面材料的燃烧性能或者安装自动喷淋系统都可以有效控制热释放速率，且在站点两端开设逃生路线、站台和地铁隧道直接卷帘的正常启动等可有效保证安全疏散。     

固体可燃物热释放速率实验研究

详述了基于耗氧原理在房间量热器中测量热释放速率的整套实验系统,试验选取由复合板组成的木箱燃烧物,测试在不同引燃方式下的热释放速率特性,通过对比和分析试验数据,得到的结论对于进一步研究建筑板材的火灾特性具有重要意义。     

聚甲基丙烯酸甲酯板材燃烧性能分析研究

应用锥形量热仪测试分析在5种不同的辐射热通量下聚甲基丙烯酸甲酯板材点燃时间、热释放速率、热释放速率峰值与其质量损失速率间的关系。样品长100 mm,宽100 mm,厚2、4、6 mm。辐射热通量为:15、25、35、45、55 kW/m~2,对应的材料表面温度为:387、490、572、645、685℃。研究发现聚甲基丙烯酸甲酯板材的点燃时间与其厚度、辐射热通量呈负相关关系。在低热辐射通量下,浇注型聚甲基丙烯酸甲酯板材点燃时间要大于挤压型板材的点燃时间。引燃后,聚甲基丙烯酸甲酯板材热释放速率峰值随辐射热通量的增加而增加,浇注型板材热释放速率的增速高于同等厚度下挤压型板材的增速。在不同的热辐射强度下,不同工艺下的聚甲基丙烯酸甲酯板材的质量损失速率差距较小。     

国内首个大型外墙保温体系火灾模拟试验模型落户北京

国内首个采用现代耗氧原理设计建成的大型屋角火灾模拟试验室外模型．El前在北京振利高新技术有限公司大兴基地建成。该模型借鉴美国标准保险商安全标准UL 1040《建筑隔热墙体火灾测试》（Fire Test of Insulated Wall Constructionl（见图1）．并做了局部调整。模型高30ft,两面成直角的墙体外侧宽度为20ft,顶面采用不燃的无机板材遮盖。     

ISO 9705房间实体火灾试验及FDS模拟研究

通过锥形量热仪试验测试家具样品的单位面积热释放速率曲线,通过ISO 9705房间实体火灾试验测试家具的热释放量、产烟量和烟气温度。基于家具物品的基本材料特性和锥形量热仪数据进行FDS模拟,与ISO 9705房间实体火灾试验数据进行对比。试验结果表明:基于锥形量热仪数据作为FDS模拟的基本输入参数,模拟得到的热释放速率结果能够更好地与试验值吻合;FDS能够很好地模拟ISO 9705房间实体火灾试验中顶棚温度及气流温度的峰值发展变化情况,但在热烟气层高度以下,模拟结果与实测值之间存在较大差异。     

基于全尺寸实验的典型壁纸燃烧性能研究

采用典型壁纸在全尺寸屋角试验台(ISO ROOM)中进行试验,通过与小尺寸试验比较,对热释放速率、温度场分布、CO和CO2释放速率等进行研究,得出两个经验性结论,并通过温度场和CO2生成率与热释放速率的线性相关性研究得出3个经验性线性公式.     

直剪试验与三轴试验的对比探讨

介绍了直剪试验与三轴试验的仪器设备及方法，通过对两种不同试验方法及结果的对比，指出三轴试验结果更接近土的实际理论值，数据更安全可靠，为岩土工程师使用抗剪强度指标提供了依据。     

Testing wall assemblies on an intermediate-scale calorimeter

A new intermediate-scale calorimeter for measuring the rate of heat release based on oxygen-consumption methodology has been developed at Weyerhaeuser Fire Technology Laboratory. A 1 m² sample, vertically oriented, can be exposed to a uniform radiant flux of up to 50 kW/m² provided by the gas-fired radiant panel. The test method was primarily developed to test wall assemblies, since features such as the joints of assembly panels, sheets of noncombustible protective materials, cracking, material collapse, and melting and spilling of thermoplastic materials cannot be represented in a bench-scale sample. Large-scale tests are expensive and time-consuming. A series of tests was run to determine whether features known to exist in real structures during a fire could be adequately represented and reproduced in this test method. The results show that the behavior characteristics during tests are consistent with heat release data.     

Experimental study on the influence of different thermal insulation materials on the fire dynamics in a reduced-scale enclosure

Four scaled (1:5) fire experiments with two identically classified types of commercially available sandwich panels incorporating either stone wool (SW) or polyisocyanurate (PIR) foam as cores were conducted using a modified version of the ISO 13784-1 (Reaction to fire tests for sandwich panel building systems — Part 1: Small room test) standard. This was to assess the suitability of scaled experiments for assessing sandwich panel fire behavior. In the modified version of the test standard (scaled and full experiments), the fire severity was increased to simulate fires that could occur in commercial premises. This was achieved by prolonging and doubling the heat release rate output of the gas burner at the end of the experiments. Furthermore, non-structural damages such as screw-hole damages were applied to the enclosures to reflect real life observations.The results showed differences in the fire behavior, depending on whether the enclosures were constructed of panels filled with SW or PIR insulation material. The mass losses of the insulation materials showed significant contribution from the PIR cores, regardless of fire load and the non-structural damage.The qualitative behavior with respect to the “flashover” failure criterion, as stated in the ISO 13784-1, was successfully obtained in all of the scaled experiments. As such, the scaled experiments mimicked the behavior of the full scale SW experiments to a satisfactory degree. However, the PIR compartments failed considerably earlier in the full scale tests than in the scaled experiments. Therefore, it can be concluded that when the energy contribution from the core material remained negligible compared to the gas burner, the measured parameters matched quite well. Therefore, if the insulating core material does not dominate the fire dynamics of the compartment and the energy from the gas burner dictates the fire scenario then the scaled set-up will predict the temperature in the full scale compartment. Based on this and with further development with respect to, especially, time, this kind of scaled experiments could be a valuable testing method for assessment of the behavior of sandwich panel, and therefore merit further studies and eventually increased use.     

Models for calculating flame spread on wall lining materials and the resulting heat release rate in a room

An extensive research programme, dealing with fire growth on combustible wall lining materials, has been ongoing in Sweden over the last decade. Several lining materials were tested in bench-scale fire tests in order to derive basic material flammability parameters. The same materials were also tested in a full scale room test and a 1/3 scale room test for two different scenarios, A and B. Scenario A refers to the case where walls and ceiling are covered by the lining material, Scenario B where lining materials are mounted on walls only.

This study utilises the results from these experiments and presents a mathematical model where material properties derived from standardised bench-scale tests are used as input data. The model predicts fire growth in the full- or 1/3 scale tests, in two different scenarios (A and B), and consists of sub-models for calculating the rate of heat release, gas temperatures, radiation to walls, wall surface temperatures and flame spread on the wall lining material.

A thermal theory of wind-aided flame spread on thick solids is examined and solutions are given and analysed for flame spread velocities under ceilings. Both numerical and analytical solutions are discussed.

The analytical solutions can be used to evaluate the flame spread propensity of materials and thus, whether a certain material is likely to go to flashover or not in the Room Corner Test. More generally, the solutions can be used to estimate whether a material will spread flame in a variety of concurrent flow flame spread scenarios. Results from the analytical solutions are compared with experimental flashover data for 22 materials, showing a good agreement.

The numerical solutions are incorporated into a simple room fire model. The results from the numerical model are compared with experiments on 22 materials tested in the full scale room for Scenario A. Comparisons for Scenario B are made with 10 materials tested in the 1/3 scale room. The results show reasonably good agreement for most materials between the model and the experiments.     

Flame Heights and Heat Transfer in Façade System Ventilation Cavities

The design of buildings using multilayer constructions poses a challenge for fire safety and needs to be understood. Narrow air gaps and cavities are common in many constructions, e.g. ventilated façade systems. In these construction systems flames can enter the cavities and fire can spread on the interior surfaces of the cavities. An experimental program was performed to investigate the influence of the cavity width on the flame heights, the fire driven upward flow and the incident heat fluxes to the inner surfaces of the cavity. The experimental setup consisted of two parallel facing non-combustible plates (0.8 × 1.8 m) and a propane gas burner placed at one of the inner surfaces. The cavity width between the plates ranged from 0.02 m to 0.1 m and the burner heat release rate was varied from 16.5 kW to 40.4 kW per m of the burner length. At least three repeated tests were performed for each scenario. In addition, tests with a single plate were performed. The flame heights did not significantly change for Q′/W < 300 kW/m² (where Q′ is the heat release rate per unit length of the burner and W is the cavity width). For higher Q′/W ratios flame extensions up to 2.2 times were observed. When the distance between the plates was reduced or the heat release rate was increased, the incident heat fluxes to the inner surface increased along the entire height of the test setup. The results can be used for analysing methodologies for predicting heat transfer and fire spread in narrow air cavities.     

ETFE薄膜屋面材料大尺寸火灾试验研究

设计了ETFE薄膜的大尺寸火灾试验,研究了在4 MW火灾规模下ETFE薄膜的燃烧特性,并探讨了在标准试验和大尺寸火灾试验条件下ETFE膜材燃烧是否出现熔滴现象.结果表明:在4 MW火灾规模下,ETFE薄膜在火焰可以接触到的位置发生软化及烧穿,并有滴落物,在火源无法接触到的位置保持完整性,未发生火蔓延;符合GB 8624...     

A room fire screening test procedure

Full-scale room fire economics necessitate a screening test procedure requiring only a small amount of material to quantitatively assess heat release rate. This test could determine which materials may justify full-scale testing and those which fail early. Such a procedure is described, sample results are given, and it is suggested that correlation of screening test results with full-room and bench-scale test methods could improve the evaluation of the pre-flashover fire spread characteristics of materials.     

Heat Release Rate of Heavy Goods Vehicle Fire in Tunnels with Fixed Water Based Fire-Fighting System

A series of large-scale fire tests for road tunnel application was conducted in a test tunnel facility in Spain. The aim of this fire tests program was to investigate the magnitude of the heat release rate generated by a fire in heavy goods vehicles (HGV’s) with and without a fire suppression system in tunnels in Singapore; the possibility of interchanging a fire suppression system with other measures such as lowering the longitudinal flow velocity; and to acquire information on the appropriate design parameters (e.g., nozzle type, discharge density and activation time) to adopt based on the most probable fuel load used in these road tunnels. In order to ensure repeatability, simulated HGV’s consisting of 228 pallets with 48 plastic pallets (20%) and 180 wooden pallets (80%) were used in all fire tests. An air velocity of approximately 3 m/s was applied. As the scope of work covered in this fire test program is very large, only the setup of the fire test and the findings on the effects of heat release rate with (Test 4) and without (Test 7) a fixed water based fire-fighting system are covered. The test results indicate that a substantial reduction of fire heat release rate can be obtained using a low-pressure deluge fire suppression system, as long as timely activation of the water is provided. However, the influence of the suppression system on CO production is significant. Such experimental data address the current dearth of knowledge on the actual effect of low-pressure deluge systems on the heat release rate from HGVs in tunnel fires.     

Modeling fire growth in a combustible corner

A fire growth model was developed to predict the flame spread and total heat release rate of a fire in a corner configuration with a combustible lining. Input data for the combustible lining were developed using small-scale test data from the ASTM E1354 cone calorimeter and ASTM E1321 LIFT. The fire growth model includes a flame spread model linked with a two zone compartment fire model, CFAST Version 3.1.2. At a user selected time interval, the flame spread model uses the gas temperature from CFAST to predict the heat release rate of the fire at that time interval, and then provides CFAST with a new heat release rate to predict conditions during the next time step. The flame spread model is an improved version of the flat wall flame spread model previously developed for the US Navy. The model is capable of predicting flame spread in a variety of configurations including a flat wall, a corner with a ceiling, flat wall with a ceiling, unconfined ceiling, and parallel walls. The model has been validated against ISO 9705 test data and was used in this study to simulate conditions that develop in three open corner tests each with a different lining material. The model was able to predict the heat release rate of the fire and provide a reasonable estimate of the flame fronts and flame lengths during the growing fire.     

成束PVC电缆全尺寸火蔓延实验研究

对最常见的PVC电缆进行了全尺寸实验研究.通过测量电缆的炭化长度及电缆表面的温度研究火蔓延的情况,同时将火蔓延与火灾过程中的重要参数(如热释放速率、烟气释放速率)进行了比较,对影响电缆火蔓延的因素进行了分析.研究发现,PVC电缆的火蔓延过程可分为两类:一类可以维持火焰传播,另一类在离开点火源后火焰逐渐熄灭;影响电缆火蔓延的关键因素为电缆的排布方式,当电缆为间隔排列时,火焰可以维持传播,当电缆为紧密排列时,火焰在电缆束中段熄灭;电缆束宽度和点火源功率对电缆火蔓延的影响很小.     

Experimental and numerical study of temperature developments in PIR core sandwich panels with joint

This paper presents the results of an experimental and numerical investigation of temperature developments in sandwich panels consisting of steel sheeting and polyisocyanurate (PIR) core. Fire experiments were carried out on individual PIR sandwich panels and PIR sandwich panels with joint. The fire test results were used to validate a temperature dependent thermal conductivity model for PIR, through numerical heat transfer modelling using the general finite element package ABAQUS. The fire test results indicate that the temperatures at the joint on the unexposed side of a sandwich panel is initially lower than that on the panel. However, at high temperatures, the ablation of PIR core creates large gaps up to 25 mm. Due to high radiation within the gap, the joint temperature becomes much higher than the panel temperature. The results of a numerical parametric study indicate that if the joint gap can be controlled to be no greater than 5 mm, the joint and the panel temperatures on the unexposed surface would be similar. Joint gaps of 10 mm or greater would result in joint temperatures much higher than panel temperatures and would reduce the sandwich panel system insulation performance of less than 60 min even though the panel may be able to reach much longer standard fire resistance rating.