Fire safety is a concern in space travel, particularly with the current plans of increasing the length of the manned space missions, and of using spacecraft atmospheres different than in Earth, such as microgravity, low-velocity gas flow, low pressure and elevated oxygen concentration. In this work, the spread of flame over a thermoplastic polymer, polymethyl methacrylate (PMMA), was conducted in the International Space Station and on Earth. The tests consisted of determining the opposed flame spread rate over PMMA cylinders under low-flow velocities ranging from 0.4 to 8 cm/s and oxygen concentrations from 15% to 21%. The data show that as the opposed flow velocity is increased, the flame spread rate first increases, and then decreases, different from that on Earth. The unique data are significant because they have only been predicted theoretically but not been observed experimentally before. Results also show that flame spread in microgravity could be faster and sustained at lower oxygen concentration (17%) than in normal gravity (18%). These findings suggest that under certain environmental conditions there could be a higher fire risk and a more difficult fire suppression in microgravity than on Earth, which would have significant implications for spacecraft fire safety.
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机译：在太空旅行中，尤其在当前增加载人航天任务的时间以及使用与地球不同的航天器大气的计划中，尤其是在微重力，低速气流，低压和氧气浓度升高的情况下，防火安全是一个令人担忧的问题。在这项工作中，火焰是在国际空间站和地球上在热塑性聚合物聚甲基丙烯酸甲酯（PMMA）上扩散的。该测试包括确定在低流速（0.4至8 cm / s）和氧浓度（15％至21％）下，PMMA气瓶上相对的火焰蔓延率。数据表明，随着反向流速的增加，火焰蔓延速率首先增加，然后减少，这与地球上的不同。独特的数据之所以重要，是因为它们仅在理论上进行了预测，而以前在实验上没有观察到。结果还表明，在低重力下（17％）比在正常重力下（18％），火焰在微重力下的扩散速度更快且持续时间更长。这些发现表明，在某些环境条件下，微重力可能比地球上具有更高的火灾风险和更困难的灭火效果，这将对航天器的消防安全产生重大影响。
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