发表机构
University of California, Los Angeles（加州大学洛杉矶分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过参数化数值模拟，探究后掠角与雷诺数对有限翼前缘分离和翼尖涡的影响，发现高雷诺数下增大后掠角可增强升力，并揭示流向涡量变化等关键机制。
AI 中文摘要
我们探究了后掠角对有限翼展机翼前缘分离与翼尖涡相互作用的影响，其中后掠角为 $\Lambda=0^\circ$ 至 $45^\circ$，半展弦比 $sAR=2$，迎角为 $14^\circ$，基于弦长的雷诺数 $Re=600$、$1000$、$2500$、$5000$ 和 $10000$。通过这一参数化研究，我们旨在弥合现有关于低雷诺数（$Re\approx 10^2$）下后掠有限翼分离流动的研究与较高雷诺数（$Re\approx10^4$）下湍流行为之间的知识空白。在此参数范围内，流动结构显著变化，从而改变升力特性。具体而言，在 $Re\leq5000$ 时增大 $\Lambda$ 会降低升力，而在 $Re>5000$ 时增大 $\Lambda$ 则会增强升力。我们基于流向涡量分析了随雷诺数增大而导致这一效应的流动变化，揭示了三个关键效应：（i）随着后掠角增大，由于展向速度分量更高，流向涡量的符号发生改变；（ii）随着机翼后掠角增大，翼尖涡逐渐减弱并最终消失，同时翼根附近出现一个占主导地位的内侧涡结构；（iii）在较高雷诺数和较大后掠角下，该内侧涡结构与主尾迹合并，增强了剪切层卷起，并在机翼上方形成一个具有延伸再附区域的前缘涡。这些发现揭示了流动特性如何随雷诺数变化，从后掠翼提供有限收益的工况过渡到显著提升气动性能的工况。本研究有助于更深入地理解后掠翼尾迹动力学，这对现代飞行器设计至关重要。
英文摘要
We explore the effect of wing sweep on the interaction between leading-edge separation and tip vortex for a finite wing with sweep angles $Λ=0^\circ$ to $45^\circ$, semi-aspect-ratio $sAR=2$, angle of attack $14^\circ$, and chord-based Reynolds numbers $Re=600$, $1000$, $2500$, $5000$, and $10000$. Through this parametric study, we seek to bridge the knowledge gap between existing studies on separated flows over swept finite wings at low Reynolds numbers ($Re\approx 10^2$) and the behavior of turbulent flows at higher Reynolds numbers ($Re\approx10^4$). The flow structure significantly varies over this range of parameters, altering the lift characteristics. Specifically, increasing $Λ$ at $Re\leq5000$ reduces the lift, while increasing $Λ$ at $Re>5000$ enhances the lift. The flow modifications that lead to this effect with increasing Reynolds number are analyzed in terms of the streamwise vorticity, revealing three key effects: (i) a change in the sign of streamwise vorticity with increasing sweep angle, due to the higher spanwise velocity component, (ii) the progressive weakening and eventual disappearance of the tip vortex, when increasing the wing sweep, is accompanied by the emergence of a dominant inboard vortical structure near the root, and (iii) at higher Reynolds numbers and sweep angles, this inboard vortical structure merges with the main wake, intensifying the shear-layer roll-up and giving rise to a leading-edge vortex with an extended reattached region over the wing. These findings reveal how the flow characteristics vary with Reynolds number, transitioning from regimes where swept wings offer limited benefit to regimes where they significantly enhance the aerodynamic performance. This study contributes to a deeper understanding of swept-wing wake dynamics, which is crucial for modern air vehicle design.
