大型储罐池火特性实验研究

为了更好的进行储罐区消防设计及消防救援,对大型储罐池火燃烧特性进行实验研究。通过设计大型储罐池火实验,利用高清摄像机进行摄像并利用软件进行分析,得出:对于油品表面敞开的池火灾,池火初始蔓延速率和方向由初始油气浓度决定,蔓延方向为油气浓度高的方向;同一油品液面池火,火焰蔓延速率先增加后减小;风使火焰蔓延速率的增加速率变大;同等情况下,柴油的蔓延速率小于汽油的蔓延速率;对于油品表面覆盖有厚层连续泡沫的池火灾,池火会向下风向蔓延,蔓延速率会先增大后减小。风对火焰脉动频率的影响不大;随着储罐直径的增加,火焰脉动频率减小。在储罐直径不变的情况下,有风时火焰长度要小于无风时火焰长度。     

航空煤油不同尺寸池火热流及温度特性研究

为研究航空煤油池火燃烧过程中热流与温度特性,搭建了油料燃烧模拟实验台架。通过分析实验图像与数据,发现航空煤油池火辐射热通量随径向距离和高度的增大逐渐减小,其中辐射热通量对高度增加更为敏感,随高度升高下降幅度更快;热辐射先于热对流达到强度最大值,随后在稳定燃烧阶段后期热对流强度存在跃升现象,强度超过热辐射强度,成为该阶段主要传热方式;航空煤油池火中心线上,下部区域火焰连续燃烧、氧气浓度低,上部区域油火卷吸空气、氧气浓度较高,是导致不同高度最高温度到达时刻不同的主要原因;对不同尺寸油池火来说,其热通量峰值随着油池尺寸增大而增大,同时方形油池热通量峰值显著高于圆形油池。     

不同几何尺寸和泄漏量的航空煤油池火燃烧特性研究

为研究不同边界和泄漏量下航空煤油燃烧过程中的红外特性、温度及热流变化规律,搭建了航空煤油池火燃烧实验系统。对实验采集的数据进行整理分析,结果表明,池火的演变经历了“着火发展-稳定燃烧-火焰衰减”的过程。在着火发展阶段,方形油池液面温度梯度大,且整体温度较圆形油池低;在稳定燃烧阶段,火焰温度沿轴线向上逐渐降低,内焰大于外焰;在火焰衰减阶段,不同油池均存在边界黏性效应,火焰先经历了轴向衰减,再由油池中心向边缘缓慢熄灭。圆形油池的传热能力优于方形油池,且随着直径增大,传热能力进一步增强;不同的泄漏量对火焰温度不会产生影响,但会增强火灾的综合热损伤能力。     

一种圆环状多层发射药的燃烧模型

为了模拟和改善多层圆环状发射药的内弹道性能和燃烧性能,建立了一种圆环状多层高能硝胺发射药的燃烧模型,定义了多层环状发射药的缓燃层与速燃层燃速之比K、缓燃层的初始总厚度与药片初始总厚度之比X、以及药片的内外径差与初始总厚度之比(宽厚比)W三个参数.得到了不同参数的多层发射药的形状函数Ψ-Z曲线,并通过中止燃烧实验对模型进行了验证.结果表明,X、K和W对多层发射药的燃烧有很大的影响,Ψ-Z曲线呈现一定的变化规律,中止燃烧实验表明该模型简单、假设合理,理论计算与实际测试符合较好.     

超高燃速推进剂的限燃包覆层

研究了超高燃速推进剂的侧面限燃包覆。通过包覆层厚度、中止燃烧、间接证明实验,证实了采用硬质PVC黏合剂为内层,添加石棉粉的醋酸纤维素为外层的包覆层,可以使超高燃速推进剂侧面不发生窜火,达到稳定对流燃烧,燃速可达1000mm／s以上。     

注气流量对火驱采油岩心燃烧特征的影响

利用火驱一维燃烧管模拟装置进行火驱干式向前燃烧工艺模拟实验,研究注气流量对火驱采油岩心燃烧特征的影响,考察不同空气流量下燃烧管温度分布、燃烧距离、燃烧持续时间、产出液体等参数研究空气流量对火烧油层的影响。结果表明,空气流量与燃烧前缘推进速度、原油消耗量成正相关关系;适当增大空气流量可提高产出油的饱和烃含量;当空气流量达到3.0L·min-1时,产出油的饱和烃含量开始减少;空气流量低于1.5L·min-1时,油层不能稳定燃烧。     

果壳生物质燃烧特性与动力学分析

为充分利用果壳生物质废弃物,采用热重分析对油茶壳、核桃壳、澳洲坚果壳进行了燃烧实验研究,考察了不同升温速率下3种果壳生物质的燃烧特性及动力学参数。结果表明：3种果壳生物质燃烧特性不同,但燃烧特性参数均随升温速率升高而增大;随着升温速率的增加,着火点、燃尽温度、最大燃烧速率、平均燃烧速率及综合燃烧特性指数提高;10℃/min时,油茶壳、核桃壳、澳洲坚果壳综合燃烧特性指数分别为0.56×10^-7、1.18×10^-7、0.88×10^-7;3种果壳生物质的燃烧反应遵循一级反应动力学模型,相关系数（R²）均达0.93以上,低温阶段活化能为30.40~52.41 kJ/mol,高温阶段活化能为18.49~40.62 kJ/mol,低温阶段活化能均大于高温阶段。     

面向变电站蓄电池火灾的壳体材料燃烧特性

采用热重分析仪研究了铅酸蓄电池壳体材料[丙烯腈–丁二烯–苯乙烯塑料(ABS)]在空气氛围,不同升温速率下的燃烧动力学特性。结果表明,蓄电池壳体材料在燃烧时分为两个失重阶段,高加热速率有利于第一阶段的燃烧过程,从而促进电池着火和稳定燃烧,但却不利于第二阶段的燃烧过程。因此,如何在火灾早期实现对蓄电池的快速降温是控制灾情的关键。此外,通过对4种常用动力学模型的综合评估,选择适用性最好的FWO模型计算得到活化能随燃烧反应的进行而不断增大,量化说明了火灾初期电池燃烧猛烈,危险性较大。     

煤颗粒燃烧过程中的热解及焦燃烧行为模拟研究

为研究煤颗粒在燃烧过程中的热解与焦燃烧行为,给解耦燃烧装置的设计和优化提供参考,基于煤燃烧过程的不同阶段(干燥阶段、热解阶段、焦燃烧阶段),结合传热传质过程和反应动力学机理,建立了单颗粒煤燃烧模型。利用该模型,分析了煤在燃烧过程中颗粒内部温度、气体组分的演化过程,以及热解阶段和焦燃烧阶段的耦合关系。结果表明,在煤燃烧过程中,靠近颗粒表面处焦的燃烧提高了颗粒内部焦燃烧的初始反应温度,导致颗粒可达到的最高温度出现在颗粒中心处;随着颗粒尺寸的增加,热解时间和总燃烧时间的差值增加,该趋势对于粒径大于4 mm的煤颗粒更加明显,意味着在解耦燃烧实际应用中应选用粒径大于4 mm的煤颗粒。     

典型航空旅客行李聚碳酸酯板材的燃烧特性

以航空旅客行李箱聚碳酸酯板材为研究对象,基于ISO 5660-1:2015标准锥形量热仪平台,采集点燃时间、热释放速率、产烟率、总产烟量等数据,分析其燃烧过程。基于实验数据,建立纯聚碳酸酯板材(PC)的点燃时间模型,预测其临界辐射热通量。结果表明,PC在燃烧后形成膨胀炭层,在不同辐射强度下外形尺寸变化大。随着辐射强度的增加,产烟率、总产烟量、质量损失率均增加,不同厚度PC的残炭剩余率为：厚度2 mm>厚度4 mm>厚度3 mm,其中残炭主要成分为鲸蜡烷、二十烷和二十二烷。对于2 mm厚的PC,热释放速率曲线只有一个峰值,而厚度为3 mm和4 mm的PC在不同辐射强度下热释放速率曲线由单峰向多峰过渡,并且热释放速率的峰宽明显增大。根据拟合曲线关系,建立了热薄型点燃时间预测模型,分别计算得出2、3和4 mm厚的PC的临界辐射热流为15.50、15.24、17.02 kW/m²。     

Experimental study of the combustion characteristics of methanol‐gasoline blends pool fires in a full‐scale tunnel

The combustion characteristics of methanol‐gasoline blends pool fires were studied in a series of full‐scale tunnel experiments conducted with different methanol and gasoline blends. The parameters were measured including the mass loss rate, the pool surface temperature, the fire plume centerline temperature, the ceiling temperature, the smoke layer temperature profile, the flame height, and the smoke layer interface height. The gasoline components were analyzed by GC‐MS. The effects of azeotropism on the combustion characteristics of the different blends were discussed. On the basis of the results of the fire plume centerline temperature, the ceiling temperature, and the flame height, it shows that the tunnel fire regime gradually switches from fuel controlled to ventilation controlled with increasing gasoline fractions in the blends. The fire plume can be divided into 3 regions by the fire plume centerline temperature for the different blends. The N‐percentage rule to determine the smoke layer interface height is found to be applicable for tunnel fires with different blends for N = 26.     

多层管状发射药燃烧性能的数值计算

为了模拟和改善层状发射药的内弹道性能和燃烧性能,建立了一种多层管状发射药的燃烧模型.在服从几何燃烧定律条件下,通过多层管状发射药的形状函数推导出其Γ-Ψ表达式.用Γ-Ψ曲线研究了多层管状发射药的缓燃层厚度与药片初始总厚度比、内外层的燃速比以及药柱厚度与药柱长度之比对其燃烧性能的影响.结果表明,(1)多层管状发射药缓燃层...     

A study of the effects of ullage during the burning of horizontal PMMA and MMA surfaces

Experimental and numerical investigations of burning of horizontal surfaces of poly methyl methacrylate and methyl methacrylate are presented. A burner used in this study allows for the fuel surface to be oriented horizontally at a given distance from the burner rim. One of the aims of this study is to understand the effects of ullage (distance between burner rim and fuel surface) on the burning rate of the fuel and the flame structure. In the case of poly methyl methacrylate, the surface at an initial ullage regresses during its burning, and in the case of methyl methacrylate, the pool level is maintained at the given ullage by supplying the fuel at the rate of its burning. Careful repeatable measurements of temperature and species fields are carried out. These reveal the structure of a small‐scale pool flame established over a polymeric fluid such as methyl methacrylate, and such data are scarce in literature. In order to complement the experimental results, fire dynamics simulator is employed to simulate the experimental cases. Flame structure and flow field in the gas phase have been presented and discussed. As the ullage increases, the burning rate decreases. This trend is explained using surface convective heat flux results.     

Experimental study of the burning behavior of n‐heptane pool fires at high altitude

The same configured calorimeters were built in Hefei (99.8 kPa) and Lhasa (66.5 kPa), respectively. Four sizes of round pans with diameters of 10, 15, 20, and 25 cm were adopted to study the effect of high altitude on the burning behavior of liquid pool fires. Analysis on the burning rate obtained in this study and in the literature at different altitudes indicates that pressure fire modeling performs better than radiation fire modeling in correlating the burning intensity (burning rate per unit area) with pressure and pool diameter for cases under low ambient pressure. The study also shows that heat release rate and combustion efficiency decrease at higher altitude. For medium pool fires, the burning intensity and heat release rate are proportional to D^5/2, thus the combustion efficiency being independent on pool sizes but decreases at higher altitude by a factor approximate to the pressure ratio. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of fuel devolatilisation on the combustion of wood chips and incineration of simulated municipal solid wastes in a packed bed

Detailed mathematical simulations as well as experiments have been carried out for the combustion of wood chips and the incineration of simulated municipal solid wastes in a bench-top stationary bed and the effects of devolatilisation rate and moisture level in the fuel were assessed in terms of ignition time, burning rate, reaction zone thickness, peak flame temperature, combustion stoichiometry and unburned gas emissions at the bed top. It is found that devolatilisation kinetic rate has a noticeable effects on the ignition time, peak flame temperature, CO and H₂ emissions at the bed top and the proportion of char burned in the final stage (char burning only) of the combustion. However, it has only a minor effect on the other parameters. Reaction zone thickness ranges from 20 to 55 mm depending on the moisture level in fuel and an increase in the moisture level causes a shift of the combustion stoichiometry to more fuel-lean conditions.     

Apparatus for investigating the burning and dripping of vertically oriented polyurethane foams

The burning and dripping behaviour of polyurethane (PU) foam is crucial for upholstered furniture fires due to the melting and dripping behaviour of the foam that results in a pool fire under the furniture, which enhances the combustion. The sample feeding vertical cone is developed to investigate the two-dimensional small-scale burning and dripping behaviour of vertically oriented PU foams where a constant irradiance is maintained at the exposed surface by means of automatic sample compensation. Seven different PU foams were investigated and classified as conventional foam or char-forming foam according to the observed surface phenomena during exposure to heat fluxes. The burning and dripping behaviour is found to depend on the foam density as well as the solid-phase char formation by the presence of fire retardant additives. The total mass loss rate and the dripping rate increase with higher foam density and with the presence of char formation. In contrary, the vaporisation rate is favoured at lower foam density and with the absence of char formation. Flexible foams of low density without the ability to form char tend to achieve low dripping rate where majority of the mass loss is via vaporisation, contributing directly to the gas-phase combustion.     

The burning behaviors of pool fire flames under low pressure

To investigate the influence of low pressure on pool fire behaviors, liquid n‐heptane pool fires with the diameters of 6, 8, and 10 cm were tested in a low‐pressure altitude chamber. The tests were conducted under different static chamber pressures, ranging from 40 to 60 to 80 to 101 kPa. Fuel mass loss and high‐speed flame video were recorded during the whole burning process of each test. The mass burning intensity is determined by the convective and radiative heat feedback to the fuel, and analysis shows that the convective part is the major contributor to fuel evaporation. Video recordings show that flame height increases with the reduction of pressure, as supported by the dimensionless analysis. The flame puffing amplitude increases under low pressure, resulting in a portion of the flame being quenched. A special phenomenon was observed from the flame videos in that flame rotation emerged at the ending burning stage, which was attributed to the Coriolis force effect. Copyright © 2014 John Wiley & Sons, Ltd.     

Combustion characteristics of crude oils

Small‐scale free‐burning pool fire tests were conducted in a cone calorimeter to obtain the combustion characteristics of 14 different crude oils. Measurements included the heat release rate based on oxygen consumption calorimetry, mass loss rate, radiative heat flux from the flame to a nearby target, liquid fuel temperature, extinction coefficient and CO₂ and CO concentrations in the exhaust duct. The effective heat of combustion, radiative heat loss fraction and smoke yield were calculated on the basis of the measured data. It was found that the heat release rate, mass loss rate, flame radiation and smoke yield were a function of the type of crude oil. The effective heat of combustion, extinction coefficient and radiative heat loss fraction were nearly constant for the range of crude oils evaluated in this programme. The heat release rate, mass loss rate, flame radiation and smoke yield appeared to correlate well with the crude oil density. Copyright © 2001 John Wiley & Sons, Ltd.     

浸没在多孔介质中的液体燃料燃烧特性的研究进展

浸没在多孔介质中的液体燃料燃烧是一类特殊的液体燃料燃烧现象,经常出现在由于管路、事故性溢出或者其他原因造成的燃油泄漏场合,主要回顾了此领域在最近几十年内的研究进展,以及在实际中的应用,介绍了浸没在多孔介质中液体燃料燃烧特性的研究,对于消除潜在火灾隐患,控制液体燃料泄漏火灾现场的火势以及利用燃烧方式清除渗入土壤或者沙滩中的液体燃料具有重要意义.