高速双锥绕流中热化学与输运模型影响研究
EFFECTS OF THERMOCHEMICAL AND TRANSPORT MODELS ON THE HIGH-SPEED DOUBLE-CONE FLOWFIELD
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摘要: 激波与边界层之间相互作用是高超声速飞行中的常见现象,对飞行器气动性能与飞行安全至关重要.对于高焓来流,流场中通常存在复杂的物理化学现象,此时准确模拟流场中激波边界层相互作用的难度大,相关物理化学建模仍有待进一步考察和研究.本文针对最近文献中纯净空气高超声速双锥绕流实验开展数值研究,分别研究了不同热化学模型与输运模型对壁面压力与热流的影响.热力学模型包括完全气体、热力学平衡和非平衡模型,化学模型包括冻结和非平衡化学模型,输运模型包括经典的Wilke/Blottner/Eucken模型与更加复杂的Gupta/SCEBD模型,以及考虑壁面催化/非催化影响的模型.计算了6个不同算例,涵盖了低焓至高焓来流等不同工况.壁面压力与热流的数值计算结果与实验结果符合较好;对于低焓来流,计算结果主要受到分子内能分布的影响,输运模型对计算结果的影响不大;对于高焓来流,一方面计算结果受到化学反应与壁面催化的影响较大,另一方面不同输运模型对计算结果的影响也更加明显.Abstract: The shock wave and boundary layer interaction is common during hypersonic flight, and it is critical for the aerodynamic performance and safety of the flight vehicle. When the enthalpy of the incoming flow is high, its numerical simulation is challenging due to many complex physics and chemistry phenomena whose modelling requires further investigation and study. Hypersonic flow around a double-cone is selected as the test case and the effects of thermochemistry and transport models on the wall pressure and heat transfer rate are studied numerically. The thermochemical models include perfect gas model, thermal non-equilibrium with frozen or non-equilibrium chemistry, and thermal equilibrium with non-equilibrium chemistry. The transport models include the widely used Wilke/Blottner/Eucken model, and the more physically complicated Gupta/SCEBD model. Moreover, the influence of wall catalysis is also considered. The six experimental test runs, covering from low to high enthalpy inflow conditions, are simulated. The computed results show that the computed wall pressure and heat flux agree with the experiments. Under the low enthalpy condition, the distribution of the molecular internal energy has a big impact on the results, and the two transport models produce similar results. Under the high enthalpy condition, the chemical reaction and wall catalysis have a significant influence. Comparison of the results with the different transport models shows much larger difference for higher freestream enthalpy.