卫星搭载聚氨酯泡沫闷烧实验

Microgravity Smoldering Combustion Experiments Aboard the China Recoverable Satellite SJ-8

SJ-8卫星搭载闷烧实验,利用长时间微重力条件,对等压条件下聚氨酯泡沫试样中的闷烧点燃和双向传播过程进行了研究,两种气流氧气浓度分别为21%和35%,气流速度为3.1 mm/s.实验结果表明,氧气浓度较小时,逆向闷烧在传播到试样末端之前将自行熄灭,同向闷烧可以自维持传播至试样末端.气流氧气浓度为35%时,逆向闷烧和同向闷烧都可自维持传播;当逆向闷烧传播至试样末端区域时反应急剧加速,导致局部发生闷烧向有焰燃烧转变;有焰燃烧进一步点燃闷烧反应留下的剩余碳,使其发生剧烈的二次氧化反应,并向下游传播直到剩余碳耗尽.实验结果为研究闷烧机理提供了基础数据,对载人航天器舱内的火灾安全具有实际意义.

The present space experiments have been conducted aboard the China recoverable satellite S J-8 to investigate the smoldering characteristics of flexible polyurethane foam with a forced oxidizer flow velocity of 3.1 mm/s. They are unique in that a combination of mixed flow opposed and forward smolder was investigated at specific ambient pressure. The results show that in the 21% O2 case, the microgravity opposed flow smolder reaction is not strong enough to progress through the foam sample and eventually extinguishes, whereas the forward smolder propagates along the entire sample length. In the 35% O2 case, both two types of smolder reaction exhibit a self-sustained propagation. Particular important is the discovery that, there is a transition from smoldering to flaming near the sample end in the opposed smolder, and it seems to be caused by the strong acceleration of smoldering reaction. This transition serves to initiate a vigorous, forward-propagating, oxidation reaction in the char left behind by the smolder reaction. The secondary char oxidation reaction propagates through the sample and consumes most of the remaining char.