Microgravity opposed-flow flame spread in polyvinyl chloride tubes
Microgravity opposed-flow flame spread in polyvinyl chloride tubes
复制标题
聚氯乙烯管中的微重力逆流火焰传播
DOI：
10.1016/j.combustflame.2008.05.014
复制
发表时间：
2008
影响因子：
4.4
通讯作者：
S. Olson
中科院分区：
文献类型：
--
作者：
George W. Sidebotham;S. Olson
在 NASA 格伦研究中心的 2.2 秒落塔中，通过实验研究了重力对受限几何形状中逆流火焰蔓延的影响。纯氧流过内径为 0.64 厘米的聚氯乙烯 (PVC) 管样品，这些样品水平或垂直放置在充满氮气的燃烧室中。用热丝在正常重力下点燃样品，一旦产生火焰，将装置掉落以观察微重力效应。在正常重力和微重力、1.0 和 0.5 atm 压力下测量火焰蔓延速率。在 1.36 cm/s 的反向流动速度下观察到低流量点火极限，此时水平、垂直和微重力火焰蔓延速率分别为 0.40、0.30 和 0.16 cm/s。对于高于约 5.2 cm/s 的流速，正常重力和微重力下的火焰蔓延速率没有差异，并且火焰蔓延速率相对于相反流速以接近平方根的依赖性增加。水平和垂直火焰的浮力流速分别估计为 2.5 和 1.5 cm/s。在 0.5 个大气压下进行的垂直测试表明，正常和微重力之间的火焰蔓延速度没有差异。这些结果表明，如果在呼吸周期的活跃阶段（吸气或呼气）避免使用高能手术工具，则无论是在空间还是地面应用中，在全身麻醉期间使用 PVC 管所带来的火灾风险都可能会降低。
The effects of gravity on opposed-flow flame spread in a confined geometry were investigated experimentally in the 2.2-s drop tower at the NASA Glenn Research Center. Pure oxygen flowed through samples of 0.64-cm-inner-diameter polyvinyl chloride (PVC) tubing held either horizontally or vertically in a combustion chamber filled with nitrogen. The sample was ignited in normal gravity with a hot wire, and once a flame was established, the apparatus was dropped to observe microgravity effects. Flame spread rate was measured in normal and microgravity at pressures of 1.0 and 0.5 atm. A low-flow ignition limit was observed at an opposed-flow velocity of 1.36 cm/s, at which point the horizontal, vertical, and microgravity flame spread rates were 0.40, 0.30, and 0.16 cm/s, respectively. For flow velocities above approximately 5.2 cm/s, there was no difference in the flame spread rates for normal and microgravity and the flame spread rate increased with a nearly square root dependence with respect to opposed-flow velocity. Buoyant flow velocities of 2.5 and 1.5 cm/s were estimated for horizontal and vertical flames, respectively. Vertical tests conducted at 0.5 atm pressure demonstrated no difference in flame spread rate between normal and microgravity. These results suggest that the fire risk associated with the use of PVC tubes during general anesthesia in either space or ground applications may be reduced if the application of a high-energy surgical tool is prevented during an active phase of the breathing cycle (inhale or exhale).