Evaluation of Chemical Equilibrium and Non-Equilibrium Properties for LOX/LH2 Reaction Schemes

ABSTRACT: Nine chemical reaction models for equilibrium schemes and six chemical models for non-equilibrium ones are studied, considering different conditions found in real liquid oxygen/liquid hydrogen rocket engines. Comparisons between two eight-species models have shown that the most complex is the best one. Besides, it was also verified that the most complex model has been the fastest, among six- and eight-species models. Both combustion temperature and thermochemical/transport properties depend only on the chemical species considered by the used model. Comparisons among results from the implemented code (Gibbs 1.3), Chemical Equilibrium with Applications and Thermochemical Information and Equilibrium Calculations, these last two codes from NASA, have shown that Gibbs 1.3 evaluates correctly both combustion temperature and thermochemical properties. Furthermore, analyses have shown that mass generation rates are very dependent on third body reaction equations and forward reaction constants.摘要：本研究结合实际液氧/液氢火箭发动机的各类工况，对9种平衡态化学反应模型及6种非平衡态化学反应模型展开了研究。通过对两款八组分模型的对比分析可知，复杂度最高的模型表现最优。此外，研究证实，在六组分与八组分模型范畴内，复杂度最高的模型同时具备最快的运算效率。燃烧温度与热化学/输运特性仅由所用模型所涵盖的化学组分决定。将本研究实现的计算程序（Gibbs 1.3）与两款由美国国家航空航天局（NASA）开发的程序——《应用化学平衡与热化学信息》（Chemical Equilibrium with Applications）及《热化学信息与平衡计算》（Thermochemical Information and Equilibrium Calculations）——的计算结果进行比对后发现，Gibbs 1.3对燃烧温度与热化学特性的计算结果均准确无误。进一步分析表明，质量生成速率极大程度上依赖于三体反应方程与正反应速率常数。