The design process is a critical issue in order to improve rocket engine performance. Indeed, the prediction of the aerodynamic forces acting on the nozzle, in particular the off-axis loads, is challenging even for modern methods. In this study, the flow of an exit Mach number Truncated Ideal Contour (TIC) nozzle is numerically investigated by means of Large-Eddy Simulation (LES), using the unstructured compressible AVBP solver developed by CERFACS. The study focuses on an over-expanded regime characterised by a Free-Shock Separation (FSS). To obtain an accurate prediction of the flow, an Adaptive Mesh Refinement (AMR) methodology is used. Results show that wall-modelled LES combined with AMR allows to accurately capture the jet flow dynamics while at the same time reducing the CPU time of LES: both the location of the mean separation point along with the pressure fluctuations inside the nozzle are well captured. In particular, the two peaks of the pressure Power Spectral Density contributing to the side-loads mechanism are correctly predicted compared to experiment.

中文翻译：

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利用大涡模拟预测火箭喷嘴的流动分离和侧向载荷

设计过程是提高火箭发动机性能的关键问题。事实上，预测作用在喷嘴上的空气动力，特别是离轴载荷，即使对于现代方法也是具有挑战性的。在这项研究中，使用 CERFACS 开发的非结构化可压缩 AVBP 求解器，通过大涡模拟 (LES) 对出口马赫数截断理想轮廓 (TIC) 喷嘴的流动进行了数值研究。该研究侧重于以自由冲击分离 (FSS) 为特征的过度扩张机制。为了获得对流动的准确预测，使用了自适应网格细化 (AMR) 方法。结果表明，壁面建模 LES 与 AMR 相结合，可以准确捕获射流动力学，同时减少 LES 的 CPU 时间：平均分离点的位置以及喷嘴内的压力波动都被很好地捕获。特别是，与实验相比，对侧向负载机制有贡献的压力功率谱密度的两个峰值被正确预测。