发表机构
Graduate Aerospace Laboratories, California Institute of Technology; Department of Aeronautics and Astronautics, Massachusetts Institute of Technology（加州理工学院高等航空实验室; 麻省理工学院航空航天系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过全局模态和瞬态增长分析，发现高焓火星进入飞行器在层流-湍流转捩中，剪切-熵层的瞬态增长是关键的线性路径，且最优增益随雷诺数线性变化。
AI 中文摘要
我们利用全局模态和瞬态增长分析，对代表火星进入条件、马赫数为26的钝头舱体上的层流-湍流转捩进行了分析，所基于的热化学基流特征对应于高空进入条件。在所考虑的雷诺数范围（$Re_\infty = 10^4$--$10^6$）内，轴对称全局特征谱保持稳定，排除了时间不稳定的轴对称全局模态作为转捩的可行路径。然而，流动仍然支持集中在由弓形激波曲率产生的剪切-熵层中的强瞬态增长。能量预算分析揭示了一个两阶段过程：平均剪切中的雷诺应力产生首先放大动能扰动，然后这些扰动在穿越强基流熵梯度时产生熵波动。最优增益随基于舱体鼻部半径的雷诺数线性缩放，而边界层局部扰动在考察的最高雷诺数下变得具有竞争力。这些结果确定了剪切-熵层瞬态增长作为高焓钝头进入飞行器中引发转捩的合理线性路径。
英文摘要
We analyze laminar-to-turbulent transition over a blunt capsule representative of Martian entry at Mach 26 using global modal and transient-growth analyses about a thermochemical base flow characteristic of high-altitude entry conditions. Across the Reynolds-number range considered ($Re_\infty = 10^4$--$10^6$), the axisymmetric global eigenspectrum remains stable, ruling out temporally unstable axisymmetric global modes as a viable route to transition. The flow nevertheless supports strong transient growth concentrated in the shear--entropy layer generated by bow-shock curvature. Energy-budget analysis reveals a two-stage process: Reynolds-stress production in the mean shear first amplifies kinetic disturbances, which then generate entropy fluctuations as they traverse the strong base-flow entropy gradient. The optimal gain scales linearly with the Reynolds number based on the capsule nose radius, whereas boundary-layer-localized disturbances become competitive at the highest Reynolds numbers examined. These results identify shear--entropy-layer transient growth as a plausible linear pathway for seeding transition in high-enthalpy blunt-entry vehicles.
Comments19 pages, 12 figures
