垃圾填埋气火焰稳定特性试验研究

针对大气式燃烧器在燃烧垃圾填埋气时的火焰稳定特性进行了实验研究,设计了一种结构简单、效果明显的填埋气火焰稳定装置.这种装置对于低热值燃气的稳定燃烧能起到较好的作用.     

PC/硅氧烷复合材料的阻燃抑烟机理研究

聚碳酸酯(PC)作为性能优异的工程塑料被广泛用于高铁、飞机等特殊领域,但其燃烧时热释放及产烟量较大,故对其进行抑烟阻燃改性便尤为重要.通过将商用有机硅阻燃剂与抗滴落剂复配制备PC复合材料,证明在添加3 wt％ 的有机硅阻燃剂后即可使PC达到V0级,LOI上升至34.5％,热释放速率峰值下降58.86％,烟及CO2释放速...     

YSZ-W复合涂层的制备及抗烧蚀性能研究

目的 在TC4表面制备均匀致密的YSZ-20％(体积分数)W(ZW2)复合涂层,以提高其抗烧蚀性能,并对其在超音速燃流中的烧蚀响应机制进行初步探究.方法 以8YSZ和W粉为原料,采用喷雾干燥-真空烧结工艺制备喷涂用ZW2复合粉末,利用大气等离子喷涂技术(APS)制备ZW2复合涂层,采用超音速火焰冲刷法(SCF)测试涂层...     

纵向通风对长大隧道火灾烟流控制分析

基于我国在长大隧道火灾安全体系研究方面的需要,采用CFD方法对长大隧道纵向式通风控制火灾烟流的问题进行了数值模拟计算,研究不同通风条件对烟流的控制效果,得出了在满足控制烟气回流的基础上排烟风速的提高与所取得的降温效果对比,以及风流经过火区后的蔓延增长变化,同时总结出烟流温度分布特征及对隧道结构不同部位的危害,可为隧道的防火与通风方案的制定,以及灾后检测评定工作提供相关的理论依据和参考。     

航空煤油薄油层燃烧特性实验研究

为研究薄油层燃烧特性,开展航空煤油薄层油池火实验,分析油品燃烧的整个过程、燃烧速率、火焰高度和辐射反馈等参数随时间的变化规律。结果表明:整个薄层燃烧过程除发展、稳定和熄灭阶段外,还存在薄层燃烧衰减阶段。稳定阶段的燃烧速率与初始油层厚度相关,但随着厚度的增加其逐渐趋于稳定;薄层燃烧衰减阶段,燃烧速率会随着实时油层厚度的下降逐渐降低。对比火焰高度的实测值和模型预测值发现,Heskestad模型的预测更接近实际结果;燃烧发展阶段后,火焰辐射反馈基本维持稳定,受初始厚度的影响较小,但辐射透射强度会随着油层厚度的降低而增加,且增速逐渐加快,表明辐射透射在薄层燃烧衰退阶段中起到关键作用。结合辐射透射的变化规律,将辐射反馈分为可吸收和不可吸收2部分,并提出用于预测辐射透射大小的经验模型。     

石墨烯对RDX机械感度及爆轰性能的影响

炸药添加剂对改善单质炸药安全与能量特性有重要作用。为研究纳米微颗粒石墨烯(Gr)对黑索今(RDX)热性能、机械感度及爆轰性能的影响,设计不同比例含量的Gr/RDX混合药剂配方,并对其进行差热、撞击感度、摩擦感度、爆速及钢凹深度的测试分析。结果表明:与纯RDX相比,Gr/RDX混合药剂DSC（差示扫描量热）曲线分解峰宽变窄、峰形更尖锐,Gr加速RDX的放热过程;Gr/RDX混合药剂撞击感度与摩擦感度随Gr比例含量的增加呈先降低后升高的趋势,少量Gr可使RDX变得钝感,含量增加时,敏化作用逐渐表现出来;Gr/RDX混合药剂爆速与钢凹深度随Gr比例含量的增加而降低;Gr含量为1%时可显著降低RDX的机械感度,而能量基本不衰减。Gr可作为RDX功能添加剂,在确保能量输出的同时,可降低机械感度、提高安全性。     

基于Matlab的短路熔痕凝固过程中熔体温度测算方法*

为解决无法对瞬时凝固的熔痕高温熔体进行测温,从而致使火灾物证鉴定界对短路熔痕组织形成规律无法达成共识的问题,使用高速摄像机采集熔痕形成时熔体的彩色影像,运用Matlab图像色温识别技术,对熔体凝固时的色彩变化进行识别与分析,从而建立测算短路熔痕凝固速率的方法。结果表明:该方法的平均标准差为9.63,标准不确定度为2.55 K,计算结果满足测试要求;在测算的10个熔痕中,灭弧瞬间熔体温度为1 734.03~2 759.15 K,初始冷却速率为-255.16~-86.61 K/ms,凝固时长为46.45~87.99 ms;灭弧时熔体温度与初始冷却速率呈近似正相关关系,与熔痕体积无关。通过此方法测算短路发生时高温熔体的温度变化,可为研究短路故障迸溅熔痕引燃、熔痕组织变化规律提供方法支持。     

Suppression of premixed flames with inert particles

Dispersal of inert particles on a flame front is one of the techniques employed to suppress explosions. The current study investigates the influence of micron-sized (75–90 μm) inert (sand) particles on the laminar burning velocity of methane-air premixtures of different equivalence ratios (0.9–1.2) and reactant temperatures (297, 350, 400 K) using a Bunsen-burner type experimental apparatus. When an inert particle interacts with the flame zone, it extracts energy from the flame, thereby acting like a heat sink and hence reducing the flame temperature. Results show that for sand particle size in the range of 75–90 μm, a concentration of 380–520 g/m³ is necessary for extinction of a methane-air flame at ambient temperature. An increase in reactant temperature reduces the heat-sink effect necessitating a higher concentration of sand to extinguish the flame. A mathematical model is developed to generalize the results and make them applicable to a wide range of parameters.     

兰姆波飞机结冰传感器的最佳工作模态研究

首先建立了兰姆波在覆盖冰层的无限大各向同性板中传播的波速方程。通过数值计算获得了在覆盖不同冰层厚度下薄板中兰姆波的色散曲线。接着绘制了在给定检测频率下兰姆波波速随厚度变化的关系曲线图,进一步提出了兰姆波飞机结冰检测过程中最佳模态的选取方法。研究结果表明冰层厚度与兰姆波波速之间存在对应关系,可以通过判断各阶模态的耦合情况来选取最佳检测模态。     

The quenching of propane deflagrations by crimped ribbon flame arrestors

Experimental studies of deflagration flame quenching by crimped ribbon flame arrestors were performed in a circular ducting with propane-air flammable mixture. The corresponding flameproof velocities were determined systemically. The results showed that the channel length, the expansion ratio and the aperture size must be taken into consideration to predict the performance of the crimped ribbon flame arrestors. To explore the relationship between flameproof velocity and arrestor structure, numerical simulations were carried out. The simulated results showed that with the reduction of the hydraulic diameter of the aperture size, the flameproof velocity is increased, which implies the basic angle must be considered when crimped ribbon flame arrestors are used to quench deflagration flame. In addition, the influence of the expansion ratio is of great significance on the efficiency of flame arrestors. The flameproof velocity can be reduced to be a value related to the expansion ratio. Two empirical formulas were derived to exhibit the relation between the flameproof velocity and the characteristics of the flame arrestor, which can be used to predict the performance of crimped ribbon arrestors.