论文标题
在有限机翼周围分离的流动中的涡度和湍流场的结构上；使用直接数值模拟分析
On the structure of Vorticity and Turbulence Fields in a separated flow around a finite wing; analysis using Direct Numerical Simulation
论文作者
论文摘要
我们研究了有限的NACA 0018机翼围绕有限的NACA 0018机翼的空间分布和生产机制，其方形侧面轮廓为$ re_c = 10^4 $和$ 10^{\ circ} $借助直接数值模拟（DNS）的攻击角度。该分析重点是尖端和近尾巴周围的高度不均匀区域。该地区高度令人费解，强烈三维，远非自相似。流动分离靠近前缘，形成了机翼中心周围的大型开放再循环区域。在尖端的接近度中，流动保持连接，但另一个较小的再循环区域形成更靠近后端。该区域强烈影响主翼尖端涡流的发展。阐明并讨论了靠近前缘的三个涡流的早期形成机制。更具体地说，我们分析了涡流拉伸/压缩和倾斜的作用，以及它如何影响每个涡流的强度，因为它接近后端。我们发现，靠近前缘的尖端的三维流动分离在吸气侧的随后涡流发育中起着重要作用。还研究并讨论了与确定的涡流模式一起研究和讨论湍流动能和雷诺应力的产生。对维持涡度和动荡动能的机制的详细分析，可以提高我们对这些高度三维非平衡流的理解，并可能导致更好的驱动方法来操纵这些流。
We investigate the spatial distributions and production mechanisms of vorticity and turbulent kinetic energy around a finite NACA 0018 wing with square wingtip profile at $Re_c=10^4$ and $10^{\circ}$ angle of attack with the aid of Direct Numerical Simulation (DNS). The analysis focuses on the highly inhomogeneous region around the tip and the near wake; this region is highly convoluted, strongly three-dimensional, and far from being self-similar. The flow separates close to the leading edge creating a large, open recirculation zone around the central part of the wing. In the proximity of the tip, the flow remains attached but another smaller recirculation zone forms closer to the trailing edge; this zone strongly affects the development of main wing tip vortex. The early formation mechanisms of three vortices close to the leading edge are elucidated and discussed. More specifically, we analyse the role of vortex stretching/compression and tilting, and how it affects the strength of each vortex as it approaches the trailing edge. We find that the three-dimensional flow separation at the sharp tip close to the leading edge plays an important role on the subsequent vortical flow development on the suction side. The production of turbulent kinetic energy and Reynolds stresses is also investigated and discussed in conjunction with the identified vortex patterns. The detailed analysis of the mechanisms that sustain vorticity and turbulent kinetic energy improves our understanding of these highly three dimensional, non-equilibrium flows and can lead to better actuation methods to manipulate these flows.
