CFD Analysis of CUBRC Base Flow Experiments
CFD Analysis of CUBRC Base Flow Experiments
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DOI：
10.2514/6.2010-1250
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发表时间：
2010-01
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影响因子：
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通讯作者：
M. Barnhardt;G. Candler;M. Maclean
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文献类型：
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作者：
M. Barnhardt;G. Candler;M. Maclean
本文介绍了在 CUBRC 48” 反射激波风洞中进行的一系列实验的计算分析结果，目的是研究尾部尾流的转变。这些实验检查了球形钝化胶囊上的流动，该胶囊粗略地选择为 NASA 目前正在设计的新猎户座乘员舱的比例表示。在这项研究中，我们重点进行了三个测试运行进行分析，分别对应于低、中和高雷诺数条件。每个案例都经过检查，旨在了解其影响在数值上，我们发现标准的时间一阶、空间二阶（带有修正的 Steger-Warming 通量）足以满足感兴趣的外部折返型流动（ReD ≤ 10 6 ），层流纳维斯托克斯模拟足以准确捕获中等雷诺数下的流场统计特征。 (ReD = 6 .3×10 6 )，分析表明传热预测可能受到层流和湍流模拟的限制。在高雷诺数 (ReD = 1 0.8 × 10 6 ) 时，实验数据与使用 Spalart-Allmaras 湍流模型的分离涡模拟 (DES) 形式的完全湍流计算最为匹配。雷诺平均纳维斯托克斯 (RANS) 和 DES 计算表明，RANS 模型无法正确捕获快速波动的流动瞬态或平均场，使用替代的二阶时间、低耗散通量方案重复 DES 计算表明，模拟捕获流动瞬态的能力得到了显着提高，并且对于优先考虑流动瞬态的应用来说，这种改进可能是至关重要的。 Steger-Warming 与低耗散方案相关，因为两者最终都会降低模拟中存在的不必要耗散水平。
This paper presents results from a computational analysis of a series of experiments conducted in the CUBRC 48” reflected shock tunnel for the purpose of studying the transition of afterbody wake flows. The experiments examined the flow over a spherically-blunted capsule, roughly chosen to be a scale representation of the new Orion crew module currently being designed by NASA. In this study, we have focused on three test runs for analysis, corresponding to low, medium, and high Reynolds number conditions. Each case has been examined with the intent of understanding the influence of turbulence modeling, time accuracy, and flux discretization on solution accuracy. Numerically, we find a standard first order in time, second order in space (with modified Steger-Warming fluxes) to be adequate for the external, reentry type flows of interest. For the low Reynolds number case (ReD ≤ 10 6 ), a laminar Navier-Stokes simulation is sufficient to accurately capture the statistical character of the flowfield. At the medium Reynolds number (ReD =6 .3×10 6 ), the analysis indicates a possibly transitional wake where heat transfer predictions are bounded by laminar and turbulent simulations. At the high Reynolds number (ReD =1 0.8 × 10 6 ), the experimental data are best matched by a fully turbulent calculation using the Detached Eddy Simulation (DES) form of the Spalart-Allmaras turbulence model. Additionally, comparisons between Reynolds-averaged Navier-Stokes (RANS) and DES calculations reveal the inability of RANS models to correctly capture either the rapidly fluctuating flow transients or mean field. Repeating the DES calculation with an alternative second order in time, low-dissipation flux scheme shows a substantial improvement in the simulation’s ability to capture flow transients and may prove crucial for applications in which this is a priority. It is observed that the improvements seen in moving from RANS to DES and from Steger-Warming to the low-dissipation scheme are related in that both ultimately reduce the level of unnecessary dissipation present in the simulation.