A detailed mechanism for the initial hypergolic reaction in liquid hydrazine/nitrogen tetroxide mixtures based on quantum chemistry calculations
A detailed mechanism for the initial hypergolic reaction in liquid hydrazine/nitrogen tetroxide mixtures based on quantum chemistry calculations
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DOI：
10.1016/j.combustflame.2021.02.035
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发表时间：
2021-07
影响因子：
4.4
通讯作者：
Y. Izato;K. Shiota;A. Miyake
中科院分区：
文献类型：
--
作者：
Y. Izato;K. Shiota;A. Miyake
这项工作确定了液态联氨（N2H4）和四氧化二氮（N2O4）接触后自燃着火的早期化学机制。这种混合物已经在航天器推进器中使用多年，有效地开发和使用这种推进剂需要了解它们在各种条件下的爆炸式点火。在CBS-QB3//ωB97X-D/SMD理论水平上对液相反应进行了量子化学计算，结果表明，N2H4+ N2O4→NH2NHNO2+ hno2反应的能垒远低于气相相同反应的预测值。在此基础上，建立了液相反应的详细动力学模型，并对N2H4/ n2o4推进剂在预混合和绝热条件下的温升进行了预测。达到n2h4沸点（114℃）的时间估计约为0.06 μs，这解释了在以前的液滴池试验中快速形成气相的原因。通过对产率和温度敏感性的分析，确定了N2H4+ N2O4→NH2NHNO2+ hno2这一步骤在引发一系列后续反应中起着最重要的作用，从而决定了温度的上升速度。
This work determined a chemical mechanism for the early stage of hypergolic ignition following contact between hydrazine (N2H4) and nitrogen tetroxide (N2O4), both in the liquid state. Such mixtures have been used in thrusters for spacecraft applications for many years, and the effective development and use of such propellants requires an understanding of their detonation-like ignition under various conditions. Liquid-phase reactions were investigated using quantum chemical calculations at the CBS-QB3//ωB97X-D/SMD level of theory, and the results showed that the energy barrier to the reaction N2H4+ N2O4→ NH2NHNO2+ HNO2was much lower than values predicted for the same reaction in the gas phase. Based on these results, a detailed kinetic model for the liquid-phase reaction was constructed and employed to predict the temperature increase obtained from N2H4/N2O4propellants under pre-mixed and adiabatic conditions. The time to reach the N2H4boiling point of 114 °C was estimated at approximately 0.06 μs, which explains the rapid formation of a vapor phase in previous droplet pool tests. Analyses of the rate of production and the temperature sensitivity established that the N2H4+ N2O4→ NH2NHNO2+ HNO2step plays the most important role in triggering a series of subsequent reactions, and thus determines the rate of temperature rise.