Large-eddy simulations of a round jet in crossflow
Large-eddy simulations of a round jet in crossflow
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DOI：
10.1017/s0022112098003346
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发表时间：
1999-01
影响因子：
3.7
通讯作者：
Lester L. Yuan;R. Street;J. Ferziger
中科院分区：
文献类型：
--
作者：
Lester L. Yuan;R. Street;J. Ferziger
本文报道了对正常发出横流的圆形射流的一系列大涡流模拟。基于横流速度和射流直径，在两个射流与横流速度比（2.0 和 3.3）以及两个雷诺数（1050 和 2100）下进行模拟。模拟计算出的平均和湍流统计数据与实验测量结果相当吻合。通过模拟再现了实验流可视化中观察到的大规模相干结构，并描述了这些结构形成的机制。讨论了相干结构对沿中心面的平均速度、解析雷诺应力和湍流动能演化的影响。在本文中，普遍存在的远场反向旋转涡旋对被证明源自一对准稳态“悬挂”涡旋。这些涡流在喷射流和喷射流侧边缘上的横流流体之间形成的倾斜混合层中形成。通过悬涡的轴向流将涡流流体从进入管流的近壁边界层输送到射流的后侧。在那里，悬涡遇到不利的压力梯度并破裂。当这种破坏发生时，涡流直径急剧扩大，并形成与射流轨迹对齐的弱反向旋转涡流对。
This paper reports on a series of large-eddy simulations of a round jet issuing normally into a crossflow. Simulations were performed at two jet-to-crossflow velocity ratios, 2.0 and 3.3, and two Reynolds numbers, 1050 and 2100, based on crossflow velocity and jet diameter. Mean and turbulent statistics computed from the simulations match experimental measurements reasonably well. Large-scale coherent structures observed in experimental flow visualizations are reproduced by the simulations, and the mechanisms by which these structures form are described. The effects of coherent structures upon the evolution of mean velocities, resolved Reynolds stresses, and turbulent kinetic energy along the centreplane are discussed. In this paper, the ubiquitous far-field counter-rotating vortex pair is shown to originate from a pair of quasi-steady ‘hanging’ vortices. These vortices form in the skewed mixing layer that develops between jet and crossflow fluid on the lateral edges of the jet. Axial flow through the hanging vortex transports vortical fluid from the near-wall boundary layer of the incoming pipe flow to the back side of the jet. There, the hanging vortex encounters an adverse pressure gradient and breaks down. As this breakdown occurs, the vortex diameter expands dramatically, and a weak counter-rotating vortex pair is formed that is aligned with the jet trajectory.