100号航空汽油池火燃烧特性试验研究

从燃烧速率及热释放速率、火焰脉动特征、热辐射特性等方面研究了100号航空汽油池火的燃烧特性.通过电子天平实时采集数据并进行处理得到池火燃烧速率,利用全尺寸热释放速率测量系统测量池火热释放速率,通过图像处理技术对池火脉动特征进行分析,通过在火焰一定距离处布置热流计得到池火热辐射特性相关参数.结果表明:100号航空汽油池火稳定燃烧速率大于普通汽油燃烧速率,最大燃烧速率和衰减因子均大于普通汽油参数值;小尺寸池火热释放速率不稳定,随着油池尺寸的增大,热释放速率稳定性增强;池火火焰周期性脉动现象非常明显,脉动频率试验值与Pagni公式预测值接近;在油池液面高度产生的辐射强度随着无量纲距离L/D的增大呈指数衰减,拟合得到的曲线公式所对应参数值与油盘等效直径呈线性关系,通过此关系得到100号航空汽油池火热辐射统一方程.     

不同直径食用油池火燃烧特性对比试验研究

为探究食用油火灾的预防、探测及灭火技术,开展不同直径食用油池火燃烧试验,测量食用油油层温度、火焰及火羽流温度、质量损失速率、以及火焰高度等参数,分析食用油池火的燃烧特性,包括其被加热-自燃-燃烧的引燃过程和油层温度、火焰及火羽流温度、质量损失速率的变化规律;分析食用油池火燃烧速率随油池直径变化的规律,并结合理论公式计算不同油池直径对应的热释放速率。结果表明:食用油池火最大燃烧速率约为2. 3 mm/min;油池直径分别为25、40、55、70和85 cm的食用油池火对应的热释放速率分别为20、60、190、375和551 k W。     

高原乙醇油池火燃烧特性实验研究*

为研究低压条件下油品燃烧特性,以乙醇油池火为研究对象,搭建高原油池火实验平台,研究不同油盘直径下乙醇油池火燃烧规律,分析燃烧速率、火焰高度和火焰脉动等参数随时间的变化规律。研究结果表明:低压条件下的乙醇油池火,燃烧速率小于同等尺度常压条件下的油池火燃烧速率;乙醇油池火的燃烧速率随油盘直径增加变化不明显;火焰高度随油池直径增加呈现显著上升趋势,并拟合推导出适用于低压乙醇池火的火焰高度公式;火焰脉动频率随油池直径增大而减小,并给出火焰脉动与油池直径的经验公式。研究结果可丰富低压乙醇燃烧的油池火实验数据,为低压乙醇油池火的风险评估提供参考。     

近墙乙醇池火热反馈对燃烧速率的影响

为了定量评估近墙乙醇池火燃烧的危险性,根据乙醇池火燃烧辐射热平衡方程,建立了简化的墙体点源辐射计算模型,与火焰高度、近墙距离等参数相关联,进而得到近墙乙醇池火墙壁热反馈下燃烧速率的理论增量,并考虑到火焰辐射的增量对燃烧速率的影响,计算得到火焰对燃烧速率的理论增量。同时,在标准燃烧室进行了5种尺寸、不同近墙距离的方形乙醇池火的验证试验。结果表明,近墙乙醇池火的平均火焰高度和燃烧速率随油盘直径增大而增大,随距墙边距离减小而增大。与距墙边30 cm的墙边火平均火焰高度相比,紧贴墙壁的平均火焰高度上升16%~20%;与距墙边30 cm的墙边火燃烧速率相比,紧贴墙壁的燃烧速率上升12%~16%。乙醇墙边池火的燃烧速率理论增量与实际测量值的偏差在5%~34%,二者具有较好的一致性,充分说明近墙乙醇池火燃烧速率的增量主要是墙壁的热反馈和火焰的热反馈共同作用的结果。     

不同通风条件下柴油池火的实验研究

为了分析不同通风条件对柴油池火燃烧特性及引燃特性的影响,进行205 mm带水垫层柴油池火的引燃实验,通过对池火燃料的质量损失速率、火焰高度、温度及热辐射等的监测,分析通风环境中柴油池火的热传递规律。结果表明:当风速为0.5 m/s时,火灾进入旺盛阶段的时间提前,火焰平均温度最高;当风速为1 m/s时,风速的增加导致油池火的质量损失速率增加,位于主火源下风向的待引燃火源获得的热辐射通量增大,火灾旺盛阶段火焰的平均温度降低,火焰高度降低,下风向相邻油盘引燃的时间提前;1 m/s情况下,205 mm带水垫层柴油池火的安全间距需增加到1D以上;通风环境对池火发展及蔓延的影响是显著的,应适当加大下风向可燃物的安全间距,合理选择通风排烟风速,优化火灾应急救援策略。     

庚烷池火多火源燃烧特性的实验研究

多火源燃烧是森林火灾和城市群发性火灾中重要而又特殊的火灾现象,相关研究很少。通过恒定控制液面高度的实验系统,对直径0.1m、0.2m和0.4m的庚烷池火在单个火源、两火源燃烧和三火源线性排列时的火焰高度、火焰体积和燃烧速率等特性进行了实验研究。研究发现,三火源燃烧时中间火源的火焰高度、火焰体积和燃烧速率明显高于两火源燃烧和单火源燃烧,三火源燃烧时边上火源与两火源的燃烧状况难以区分。这些燃烧特性随着火源间距的减小,呈现增大趋势。热量反馈增强和空气卷吸受限这两种火源相互作用机制相互耦合,且随着火源间距的减小而增强,在S/D（S为火源间距,D为油池直径）为2～4时,两种机制强烈竞争,在其他参数范围内热量反馈增强效应占主导作用。研究还发现火焰体积与热释放速率有较好的线性相关关系,单位火焰体积的热释放速率约为1614kW/m3。     

正方形煤油池火燃烧特性研究

实验研究了无风条件下正方形煤油池火的燃烧特性,包括燃烧速率、火焰高度和火焰脉动频率等。正方形油池边长分别为0．2m,0．4m,0．6m,0．8m,油池壁面高度均为0．13m。利用图像处理技术分析了油池火火焰高度,并在此基础上建立了获取火焰脉动频率的两种方法。研究发现,油池壁面高度的存在使油池火的燃烧速率低于理论值;燃烧速率实验值与油池特征尺寸（d／L）呈单调递减关系;较小尺度油池的平均火焰高度与理论预测值比较接近,但较大尺度油池的平均火焰高度明显低于理论预测值;油池壁面的存在使油池火脉动频率低于理论值;随特征尺度（d／L）的增加火焰的脉动频率范围加大,脉动不稳定加剧。     

狭长空间内通风对航空煤油池火燃烧速率的影响

在风速0～2.3 m/s、5.6 m×0.8 m×0.8 m的低湍流狭长风洞内对边长3～9 cm的正方形航空煤油池火进行燃烧试验,结合FDS数值模拟,研究了狭长空间内通风和油盘尺寸对正方形航空煤油池火燃烧速率的影响,并做出相应的分析.结果表明,数值模拟结果和试验结果吻合得较好.航空煤油的燃烧速率随风速的增大而升高,且油盘下风侧壁面对燃料的导热加强是促进燃烧的主要因素.随着油盘尺寸的增大,油池获得的热反馈增强,航空煤油燃烧加剧.     

KI50X特高压变压器油火灾特性参数分析

为了获得KI50X特高压变压器油火灾特性参数,在大空间试验厅中,通过在不同尺寸油盘中燃烧KI50X型特高压换流变压器油,测量了燃烧速率、火焰平均高度、羽流轴向温度等燃烧特性参数。详细讨论了燃料初始温度、燃料厚度、油池直径等对燃烧速率、火焰平均高度、羽流轴向温度的影响。燃料厚度对质量损失速率有较大影响,燃料厚度为20mm时,可以观察到包括:(Ⅰ)初始增长、(Ⅱ)准稳态燃烧和(Ⅲ)衰减至熄灭3个典型燃烧阶段,因此燃料厚度都设为20 mm。当初始燃料温度从25℃升高到90℃时,会出现整体沸腾现象,导致质量损失率出现第二个峰值。此外,分别提出了在常温(25℃)和高温(90℃)下,油池直径与稳定阶段燃烧速率的关联式参数。通过对试验数据的拟合,在过渡火焰和总湍流火焰条件下,KI50X型特高压换流变压器油的燃烧速率符合液体燃料燃烧速率与油池直径的一般关系。火源上方无量纲高度处的轴向无量纲温度分布与Z/D成正比。拟合得到的轴向平均温度分布关系式表明,随轴向高度与KI50X变压器油池直径之比的增大,轴向无量纲温度升高比生物柴油和正庚烷油池快。最后系统地给出了25℃及90℃下KI50X型特高压变压器油燃烧特性拟合公式的一系列参数。     

有风条件下航空煤油池火燃烧特性的实验研究

在全尺寸热释放速率实验台的基础上,搭建有风条件池火实验平台,开展了不同风速条件下的航空煤油池火燃烧实验,实验所用正方形油盘的边长分别为0.2m、0.3m和0.4m,风速范围为0 m.s-1至4.99 m.s-1。实验结果表明,风速为0 m.s-1时航空煤油池火的燃烧速率随油盘尺寸增大而单调递增,实验值与理论值的差距随风速增大而减小。实验所得.m″windy/.ms″till与v/D呈线性关系,与前人结论一致,但实验所得参数与前人值不同。同尺寸油盘池火的热释放速率峰值来临时间随风速增大有减小的趋势;不同尺寸油池火的燃烧速率随风速增加而单调递增。对不同尺寸油池火的热释放速率峰值随风速的变化规律作了讨论。     

变压器油池火燃烧规律的实验研究*

为对变压器油池火灾进行准确有效的灭火,研究不同尺寸和不同厚度下变压器油的火灾动力学特征和基本燃烧特性,具体分析变压器油的燃烧过程和变压器油燃烧速率、火焰温度以及辐射热流随油池直径以及厚度的变化规律。结果表明:整个油品的燃烧过程分为预热燃烧阶段、稳定燃烧阶段和火焰熄灭阶段。对于厚度大于10 mm的油池燃烧,稳定阶段的燃烧速率与油层厚度无关,稳定阶段的燃烧速率随着油池直径的增加而增加。同时,变压器油火灾连续火焰区温度接近750 ℃。对于稳定燃烧阶段下的变压器油燃烧,基于辐射通量可得出在燃烧过程中,辐射热量占总燃烧热的占比约为1/3。研究结果可丰富变压器油燃烧的基础数据,为变压器火灾的灭火提供参考。     

An experimental study on the burning rate of a continuously released n-heptane spill fire on an open water surface

Spill fires are common during oil product storage and transportation after a loss of containment. Since the burning fuel is moving and the fuel depth is quite shallow, the burning rate in a spill fire is different from that of a pool fire with a static burning zone. Unlike pool fires, which have been studied for decades and have well-established correlations for burning rate, research on spill fires is inadequate. In this paper, continuously released n-heptane spill fire experiments were conducted on open water surfaces with varying fuel discharge rates. The pool diameters were measured, and the spill fire burning rates were estimated based on a dynamic balance between fuel supply and combustion. The burning rates in n-heptane pool fires from the literature were reviewed and compared with the estimated burning rates in spill fires of the same dimension. The spill fire burning rate was found to be close to that in a pool fire during the initial burning phase but lower than that in a bulk burning pool fire and that in a “fuel-level-controlled” pool fire. The distinction between the burning rates of spill fires and pool fires is explained by the heat balance analysis of the fuel layer. A model for the spill fire burning rate was proposed accordingly. The results calculated with the presented model are closer to the measured data than those calculated with pool fire models.     

An experimental and modeling study of continuous liquid fuel spill fires on water

The spread of burning fuel spilled from oil product containers during offshore storage and transportation may cause large damage and trigger further accidents. Some analytical models already exist to predict the spread and burning behavior of liquid fuel spill fires, however, few experimental studies have been conducted to verify the model results. In this paper, continuous n-heptane spill fire experiments were conducted in a rectangular trench covered with water. The burning area, fuel spread rate, and thermal flux with different discharge flow rates and ignition delay times were investigated by both experimental and modeling means. The spill fire burning area, with 5 typical phases during burning, has a quasi-steady value which is directly proportional to the discharge rate but irrelevant to the ignition delay times. The steady burning rate, as the ratio of discharge rate over burning area, was estimated. A spread model was modified to simulate the spread of continuous liquid fuel spill fires in a one-dimensional channel, based on the balance between gravity and viscous forces. A cuboid solid flame model was used to compute the thermal flux from spill fires. The burning fuel spread and the heat flux calculated by the models agree with the experimental results.     

The study of burning behaviors and quantitative risk assessment for 0# diesel oil pool fires

The liquid fuel safety issues on fuel storage, transportation and processing have gained most attention because of the high fire risk. In this paper, some 0# diesel pool fire experiments with different diameters (0.2–1 m) were conducted with initial fuel thicknesses of 2 cm and 4 cm, respectively, to obtain liquid fuel combustion characteristics. Some key parameters including mass burning rate, flame height and the flame radiative heat flux, associated with fire risk, were investigated and determined. Subsequently, a detail quantitative risk assessment framework for 0# diesel pool fire is proposed based on the 0# diesel burning characteristics. In the framework, the probability of personal dead and the facility failure are calculated by the vulnerability models, respectively. In the end, 10 special tank fire scenarios were selected to show the whole risk calculation process. The tank diameter and the distance to pool fires were paid more attention in the cases. The safety distances in the cases are provided for the persons and nearby facilities, respectively. The paper enriches the basic experimental data and the provided framework is useful to the management of 0# diesel tank areas.     

基于FERC模型的油品流淌火灾定量风险评估方法研究

为了评价油品储运过程中的流淌火灾风险,提出1种基于FERC模型的油品流淌火灾定量风险评估方法。以某汽油管道为例,分析大孔泄漏、中孔泄漏、小孔泄漏３种模式下流淌火各参数的动态变化过程,计算管道周边不同位置处的个人风险值。研究结果表明:流淌火燃烧面积的最大值随泄漏速率的增加而增大,对于给定的算例条件,大孔泄漏情景下的最大燃烧半径较小孔泄漏增大了18.4倍;相较小孔泄漏,大孔泄漏下安全距离增大了6.7倍;在距离泄漏点100 m的位置,小孔泄漏、中孔泄漏和大孔泄漏条件下的辐射热流密度值分别为0.13,1.34,8.02 kW/m2;距离泄漏点34 m处时,大孔泄漏已经占总个人风险的99%;在开展风险评价时,应着重分析大孔泄漏的情景。     

装置进气口宽度对不同尺寸油盘火旋风燃烧特性影响的研究

为探究进气口宽度对火旋风燃烧特性的影响,利用自然驱动的四面边墙夹缝式装置对不同进气口宽度使用１５０,２００,２５０ mm 3种直径进行实验研究。由燃料质量随时间变化曲线得出准稳态阶段火旋风的质量燃烧速率;利用摄像机记录火焰的连续图像并获得火焰高度。结果表明:针对实验室小型火旋风（150~250 mm）,在进气口宽度为35 mm左右时,火旋风的燃烧速率最大,即火旋风的燃烧强度存在1个最佳的进气口宽度;当火焰高度达到最高时,环量也存在1个临界值。     

Impact of wind on in-situ burning behavior of spilled oil on open water

Spilled oil may cause serious environmental pollution and ecological destruction. Thus, an efficient oil spill response is essential to reduce and minimize the impacts seen from an oil spill. In-situ burning (ISB) has been proven to be one of the most convenient and efficient treatment methods for oil spills on sea. When in-situ burning operation is carried out on sea, the wind is usually available. Spilled oil pool fire flame will be blown to tilt with an angle from the vertical direction and the flame length will be stretched. This effect of flame on downstream will be significantly enhanced. It may even cause the burning of spilled oil out of control or hazard the operators near site. Therefore, it is meaningful to study the burning behavior of oil pool fire on open water under wind.A small-scale oil pool fire on open water experiment system was designed, which could simulate the boundary conditions of sea surface ISB. A series of experiments were carried out to study the effects of oil pool diameter, oil layer thickness and wind speed on fire flame length and flame tilt angle. Flame characteristics and temperature of burning system were recorded. This study observes burning behavior to evolve from short pool fire to long declining phase which transient through boilover stage. Dimensionless flame length in pool fire stage increases with wind speed. As expected the flame tilt is strongly influenced by wind speed, tilt angle increase with wind speed. The observed experimental behavior is captured as improvement in the flame length and flame tilt angle models.This study helped better understanding fire behavior in evolving environmental conditions, and the most importantly developed model would help guide better assessment of fire mitigation strategies.