预混C2H4/N2O推进系统因其性能高、系统简单以及推进剂无毒而在姿轨控发动机中有重大潜在应用价值，而防止回火是其要解决的关键技术。为此，该文构建了包括集气腔、喷注面板、燃烧室和喷管的预混C2H4/N2O推进剂单喷注单元推力室，采用能够准确预测着火延迟的C2H4/N2O详细化学反应动力学机理，耦合腔室中的反应流和喷注面板中的传热过程，开展了推力室点燃和集气腔热反侵着火现象的数值模拟研究。结果表明：推力室非稳态点燃过程时空演化至稳定状态时的特征参数与化学热力平衡计算结果一致。随着喷注面板孔板面积比的减小，燃烧室通过喷注面板传给集气腔的热量显著增加，并最终能够引燃集气腔预混气。从而发现和提出一种喷注面板热反侵导致集气腔着火的机制。当采用常规设计的推力室头部时，存在喷注面板临界孔板面积比，其为预混C2H4/N2O推进系统喷注器设计提供了新的约束准则。
The premixed C2H4/N2O propulsion system has significant potential for attitude and orbit control thrusters since the propellant is not toxic and the systems are efficient and simple. However, methods are needed to prevent flashback. This study used a numerical model to analyze ignition in a thruster chamber with a single injector unit with a premixed C2H4/N2O propellant. The model included the plenum chamber, injection panel, combustion chamber and nozzle. The numerical model included a detailed chemical reaction mechanism for the ignition in the combustor and plenum chamber by coupling the reacting flow in the entire model and the heat transfer in the injection panel. The model predicts the spatio-temporal evolution of the unsteady ignition process in the thruster chamber and the steady characteristics are consistent with the results of chemical equilibrium calculations. Reducing the hole to the panel area ratio significantly increased the soak-back heat from the combustion chamber to the plenum chamber through the injection panel which eventually led to ignition of the premixed C2H4/N2O propellant in the plenum chamber. This is a new flashback mode induced by structural heat transfer through the injection panel. This process has a critical hole to panel area ratio for this propellant with a conventional chamber head. Thus, a new constraint criterion is given for the injection panel design of a premixed C2H4/N2O propulsion system.
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