氧化铁粒径对固体推进剂火焰特征参数影响的试验研究

针对5-氨基四氮唑/硝酸锶固体推进剂在实际应用中存在的推进剂火焰偏大、容易在灭火装置喷口处形成外喷火焰的问题,选用了微米氧化铁和纳米氧化铁作为催化剂,分别从火焰形态、质量损失速率、热释放速率、无量纲火焰高度模型几个角度开展研究,对比了两种不同粒径的氧化铁对5-氨基四氮唑/硝酸锶固体推进剂燃烧火焰的优化效果。根据燃烧试验结果,发现不论是富氧燃烧还是贫氧燃烧,在降低推进剂燃烧时的火焰高度方面,微米氧化铁均明显优于纳米氧化铁;在提高质量损失速率方面,微米氧化铁的加速效果也要优于纳米氧化铁。基于传统的液态燃料油池火发展的火焰高度预测模型,将无量纲火焰高度与热释放速率的分析关系应用到固体推进剂燃烧领域,考虑使用无量纲火焰高度的分析方法,对固体推进剂燃烧过程中的火焰高度进行预测,建立了5-氨基四氮唑/硝酸锶固体推进剂的无量纲火焰高度模型,发现不含氧化铁和含有氧化铁的5-氨基四氮唑/硝酸锶固体推进剂燃烧时的火焰高度与热释放速率的n次方成正比,该无量纲拟合可以对固体推进剂火焰高度进行预测。最终,得出了微米氧化铁比纳米氧化铁更适合作为催化剂被用于5-氨基四氮唑/硝酸锶推进剂中,有利于提高固体推进式灭火装置的灭火效果。

Effect of ferric oxide particle size on flame of propellants: An experimental study

In view of the drawbacks of 5-aminotetrazole/strontium nitrate solid propellant including the large flame and the formation of spray flame at fire extinguisher outlet, micron-sized and nano-sized ferric oxides are chosen as catalysts to modify the combustion behaviors of propellants. The optimization effect of ferric oxide is compared mainly from the perspective of flame shape, mass loss rate, heat release rate, and dimensionless flame height. Results show that under both oxygen-enriched and oxygen-depleted states, micron-sized ferric oxide performs better than the nano-sized one at decreasing flame height and increasing mass loss rate. The analytical methods of dimensionless flame height and mass loss rate in the classic flame height prediction model of liquid pool fire are employed to build the dimensionless flame height model of propellant. It is found that the flame height of 5-aminotetrazole/strontium nitrate propellant can be correlated with the heat release rate by a power law. It is concluded that the micron-sized ferric oxide is more suitable to be applied as catalyst into solid propellant than the nano-sized one, which is beneficial to improving fire-fighting efficiency of solid propellant gas generators.