火箭推进

为揭示非催化点火方式的硝酸羟胺(HAN)基单组元液体火箭发动机内推进剂的反应机理,采用分子动力学模拟方法,在ReaxFF/lg力场下对HAN基推进剂热分解机理及配方影响作用机制开展研究。计算结果表明:推进剂热分解过程存在两个阶段。第一个阶段为吸热阶段,推进剂内硝酸羟胺和硝酸肼氢键断裂,分解生成羟胺、肼和硝酸,吸热阶段主要受推进剂内氢键个数影响; 第二个阶段为推进剂分解反应阶段,由硝酸和羟胺的分解所引发,生成NH2、NO2和OH。OH为主要的氧化性物质,与肼、甲醇反应,生成大量的水。肼在推进剂中的分解主要依靠与OH反应脱氢,生成N2H3,并最终分解形成N2和H2。推进剂配方仅对与OH的反应有显著影响。降低甲醇的含量,能够显著提升燃料的反应速率,同时促进肼分子的反应脱氢,提高推进剂初始分解速率; 提高硝酸羟胺的含量能够促进甲醇的分解,但受肼分解反应速率较低的影响,推进剂整体分解速率降低。

In order to reveal the decomposition mechanism of hydroxylamine nitrate(HAN)based monopropellant in non catalytic monopropellant liquid rocket engine, molecular dynamic simulation method based on ReaxFF/lg force field was used to study both thethermal decomposition mechanism and the influence of propellant formulation. The calculation results show that there are two stages in the thermal decomposition process of the propellant. The first stage is the endothermic stage, where the hydrogen bonds of hydroxylamine nitrate and hydrazine nitrate in the propellant break and decompose to form hydroxylamine, hydrazine, and nitric acid. The endothermic stage is mainly affected by the number of hydrogen bonds in the monopropellant. The second stage is the propellant decomposition stage, which is triggered by the decomposition of nitric acid and hydroxylamine, generating NH2, NO2, and OH. OH is the main oxidizing substance that reacts with hydrazine and methanol to produce a large amount of water. The decomposition of hydrazine mainly depends on dehydrogenation with OH, and generates N2H3. N2 and H2 are the final products. The propellant formulation only has a significant impact on the reaction with OH. Reducing the proportion of methanol can significantly increase the reaction rate of fuel, while promoting the dehydrogenation of hydrazine molecules and increasing the initial decomposition rate of propellant. Increasing the content of hydroxylamine nitrate can promote the decomposition of methanol. However, due to the low rate constant of the reaction of hydrazine, the reaction rate of the propellant decomposition is reduced.

引言
1 计算方法和模型
2 结果与讨论
3 结论

图1 基于量子化学计算方法获得的硝酸羟胺与硝酸肼分子结构[23-24]<br/>Fig.1 The molecular structure of hydroxylamine nitrate and hydrazine nitrate based on quantum chemical calculation method[23-24]

图1 基于量子化学计算方法获得的硝酸羟胺与硝酸肼分子结构[23-24]
Fig.1 The molecular structure of hydroxylamine nitrate and hydrazine nitrate based on quantum chemical calculation method[23-24]

图2 基于文献[23]中方法获得的甲醇与水分子结构<br/>Fig.2 The molecular structure of methanol and water based on the calculation method in Ref.[23]

图2 基于文献[23]中方法获得的甲醇与水分子结构
Fig.2 The molecular structure of methanol and water based on the calculation method in Ref.[23]

图3 HAN基推进剂结构<br/>Fig.3 Schematic diagram of HAN based propellant structure

图3 HAN基推进剂结构
Fig.3 Schematic diagram of HAN based propellant structure

表1 不同工况下推进剂内各组分质量百分比<br/>Tab.1 The content of every component in the propellant

表1 不同工况下推进剂内各组分质量百分比
Tab.1 The content of every component in the propellant

图4 3种不同配方条件下推进剂分解过程相对势能变化曲线<br/>Fig.4 Evolution curves of HAN based propellant structure

图4 3种不同配方条件下推进剂分解过程相对势能变化曲线
Fig.4 Evolution curves of HAN based propellant structure

表2 HAN基推进剂热分解过程主要反应<br/>Tab.2 Main reaction of the thermal decomposition process of HAN based monopropellant

表2 HAN基推进剂热分解过程主要反应
Tab.2 Main reaction of the thermal decomposition process of HAN based monopropellant

图5 5个核心反应的净反应速率<br/>Fig.5 Net reaction rate of five core reactions

图5 5个核心反应的净反应速率
Fig.5 Net reaction rate of five core reactions

图6 不同配方条件下推进剂中间产物演变曲线<br/>Fig.6 Evolution curves of intermediate products in

图6 不同配方条件下推进剂中间产物演变曲线
Fig.6 Evolution curves of intermediate products in

图7 不同配方条件下推进剂分解产物演变曲线<br/>Fig.7 Evolution curves of decomposition products in monopropellants under different formulation conditions

图7 不同配方条件下推进剂分解产物演变曲线
Fig.7 Evolution curves of decomposition products in monopropellants under different formulation conditions

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备注

引言

1 计算方法和模型

2 结果与讨论

3 结论

期刊信息