阴燃火灾的调查

论述了以香烟作为阴燃火灾最常见的起火源，由阴燃火转化为有焰燃烧的机理，以及阴燃在火灾中形成的痕迹特征。     

Radiant smoldering ignition of plywood

This paper investigates the role of self-heating in the smoldering ignition of 18 mm (three-quarter inch) thick maple plywood exposed to radiant heat fluxes between 6 and 15 kW/m² in the cone calorimeter for up to 8 h. The minimum heat flux for smoldering ignition was experimentally determined to be 7.5 kW/m². This compares favorably to predictions made using classical self-heating theory. The role of self-heating was explored via temperature measurements distributed within the specimens. Elevated subsurface temperature profiles indicated self-heating was an important ignition factor resulting in ignition at depth with smolder propagation to the surface and into the material. The ignition depth was shown to be a function of the heat flux with the depth moving towards the surface as the heat flux increased.     

中国少数民族文学史书写的变迁——从《“多民族文学史观”简略》谈起

从历时性分析发现,从集体创作到个人创作,从突出作品到有个人的观点,从按照地理分布编排到民间文学与作家文学的分类,这是中国少数民族文学史书写的基本变迁线索;相应地,中国少数民族文学也逐渐被关注,被重视,从过去的引起注意,到现在的自成体系,不断成熟。中国少数民族文学史的"多民族文学史观"书写者功不可没。     

聚氨酯泡沫材料阴燃特性的实验研究

简要介绍了阴燃燃烧的定义、特点和研究意义，通过一系列实验，对自然对流条件下聚氨酯泡沫的向上正向阴燃及其传播过程进行了研究，并针对实验中出现的典型现象进行了细致分析，得出了相应的结论。     

林地腐殖质火阴燃特征研究

为了掌握林地腐殖质火阴燃温度变化特征。以南京栖霞区丁山的地表腐殖质可燃物为研究对象,将可燃物种类、可燃物燃烧深度、含水量、风速分别作为自变量,在其他条件相同的情况下分组实验对照,建立了初步的阴燃蔓延模型,得出相关实验数据。数据表明,枯立木阴燃温度最高能达到689 ℃;地表土阴燃燃烧深度越深,阴燃持续的时间就越长,发生在土层表面横向的阴燃火蔓延决定了阴燃林火的范围,此外,因为阴燃的地下燃烧特征,阴燃会在地下将可燃物烧净,而地表没有燃烧,从而呈现空洞特征;当含水率大于42.3%时,腐殖质复燃的可能性极低;通过对比观察结果,风速对阴燃的复燃影响最为显著,燃烧深度则影响阴燃时间和燃烧范围。相关研究为今后的森林消防工作提供部分理论依据和实验数据支撑。     

Onset of smoldering in cotton: Effects of density

The ignition temperature for smoldering in cotton has been determined for several densities. Experiments and consistent theoretical calculations show that an increase in density leads to decrease in ignition temperature. Experimentally it is found that repeated heating of a cotton sample results in a higher ignition temperature than for samples heated once, as a result of partial decomposition during heating. For the lowest density investigated, smoldering occurs but is not self-sustained. The smoldering front moves through the cotton with a velocity independent of the density. The mass loss rate due to smoldering increases with density. It can be concluded that density affects both the ignition temperatures and the mass loss rates in a systematic way.     

熄灭森林阴燃火的细水雾喷头设计与仿真

森林大火后的残余地表余火及地下阴燃火是引起二次森林火灾的主要原因,为防止发生二次森林火灾,清理森林余火和阴燃火是必要的.细水雾作为哈龙灭火剂的最佳替代品,被广泛应用在消防领域.本文设计一种适合熄灭森林余火和阴燃火的撞击分流高压细水雾喷头,采用Fluent进行喷头流域的仿真,分析喷孔孔径、喷孔长度和喷孔喷雾锥角对喷出细水...     

Determination of smoldering time and thermal characteristics of firebrands under laboratory conditions

The laboratory experiment was conducted to simulate the transfer of smouldering particles produced in forest wildfires by a heated gas flow. The pine bark pieces with the linear dimensions L=(15; 20; 30) mm and a thickness of h=(4−5) mm were selected as model particles. The rate and temperature of the incident flow varied in the range of 1–3 m/s and 80–85 °C, respectively. The temperature of the samples was recorded using a thermal imager. To determine the minimum smouldering temperature of pine bark, the thermal analysis was conducted. The minimum smouldering temperature of pine bark was found to be 190 °C. This temperature will cause thermal decomposition of bark only at the first stage (oxidation of resinous components). In the study the smouldering time, the temperature and the weight of samples were obtained and analyzed under various experimental conditions. The data analysis shows that the increase in the particle size leads to the decrease in their mass loss, and the rate change of the incident flow does not practically influence the mass change. For particles with the linear dimensions of 10 mm and 20 mm, the mass varies from 6% to 25%. The maximum mass loss is observed for the flows with a rate of 1 and 2 m/s. The results have shown that the increase in the particle size leads to the increase in the smouldering time. The position of the particle plays an important role, the effect of which increases with increasing the particle size. The calculations showed that the smouldering time of bark samples is long enough for the particles to serve as new sources of spot fires. The particles were found to be transported to a distance of 218 m from the fire line which can certainly influence the propagation of the fire front.     

Smoke detection of smoldering fires in a typical Melbourne dwelling

Operation of domestic smoke detectors (photoelectric and ionization) has been investigated in a typical Melbourne dwelling using smoke from smoldering hardboard and artificial smoke generated at three widely different rates. Detector performance was assessed according to the escape time offered by its operation, this being based on the criterion of visibility needed to effect escape. Under these test conditions detectors located in bedrooms performed adequately only when smoke originated in the same room; they provided poor escape times for smoke originating elsewhere. Also, ionization detectors usually provided adequate escape times only when smoke travel from the source room to the rest of the dwelling was restrained by small door openings, since it then took longer for visibility to be lost. Photoelectric detectors were generally more effective than ionization detectors, as expected for smoldering conditions, and when located in the hallway provided adequate escape times for most conditions of size and location of smoke source. Reference: P. F. Johnson and S. K. Brown, Smoke Detection of Smoldering Fires in a Typical Melbourne Dwelling,Fire Technology, Vol. 22, No. 4, November 1986, p. 295.     

聚氨酯软泡热解动力学与阴燃点燃特性研究

利用热重-红外联用技术研究了无阻燃聚氨酯软泡在空气气氛下的热解行为,采用遗传算法计算得到"4组分4阶段反应"全局表观动力学模型。在自制小尺寸火灾可燃物阴燃试验台上对无阻燃聚氨酯软泡进行点燃实验研究,分析加热至不同温度下可燃物表面温度变化。结果表明,点燃过程可燃物反应机理与表观热解动力学模型趋于一致,点燃过程分为自加热酝酿期(TC1>200℃)、热解吸热期(200℃265℃),聚氨酯软泡的临界阴燃点燃温度为328℃。