Abstract Numerical simulations of carbon dioxide and air flows are presented for the Mars Pathfinder experimental capsule configuration under hypersonic conditions. Despite the low density flows, it is shown that the medium can be modeled as a continuum and that a laminar flow approximation is valid. The finite volume method is used to solve the Navier-Stokes equations including Park’s two-temperature model for chemical dissociation and ionization. Results are presented in terms of heat flux distributions over the capsule surface and good agreement is observed between simulations and experimental data. Although freestream conditions are relatively similar for both gas mixtures, the different shock wave topologies and species dissociation profiles lead to changes with respect to thermal non-equilibrium, presented in terms of the translational-rotational and vibrational-electronic temperature modes. Ionization effects are also investigated for an air flow at more extreme conditions, with an even lower freestream density and higher Mach number. An assessment of chemical species models shows that ionization of free nitrogen and oxygen atoms in the air mixture must be accurately captured since it causes large variations in the thermal non-equilibrium process, substantially altering the surface heat flux.

中文翻译：

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热力学非平衡状态下二氧化碳和空气高超声速流动的热分析

摘要 提出了高超声速条件下火星探路者实验舱配置的二氧化碳和空气流动的数值模拟。尽管低密度流动，但表明介质可以被建模为连续介质并且层流近似是有效的。有限体积法用于求解 Navier-Stokes 方程，包括用于化学解离和电离的 Park 两温度模型。结果以胶囊表面上的热通量分布表示，并且在模拟和实验数据之间观察到良好的一致性。尽管两种气体混合物的自由流条件相对相似，但不同的冲击波拓扑和物种解离曲线会导致热非平衡方面的变化，以平移-旋转和振动-电子温度模式表示。还研究了更极端条件下空气流的电离效应，具有更低的自由流密度和更高的马赫数。对化学物质模型的评估表明，必须准确捕获空气混合物中游离氮和氧原子的电离，因为它会导致热非平衡过程发生很大变化，从而显着改变表面热通量。