Abstract Two-point hot-wire measurements were conducted to assess the scaling of coherent structures in turbulent round jets. A scale-dependent coherence analysis was applied to datasets consisting of two-point synchronized axial velocity measurements with varying radial separations between the hot-wire positions while the reference hot-wire was fixed at the centreline and two off centreline positions in different datasets. Measurements were carried out at R e D = 10000 , 20000, and 50000 and a range of axial locations (3 ≤ x/D ≤ 25). The scale-dependent coherence analysis reveals a hierarchical structure of eddies over the axial range 15 ≤ x/D ≤ 25 for λx/y0.5 ≈ 3.4 was found at R e D = 10000 . The aspect ratio increases to ≈ 3.9 at R e D = 20000 , and ≈ 4.7 at R e D = 50000 . These values are significantly smaller than the aspect ratio of = 14 observed in turbulent boundary layers. The eddy structure aspect ratio is not affected by the axial distance from the nozzle (within x / D = 15 − 25 ) or shear layer manipulation by control rings. However, the stochastic radial span of the largest eddies was found to change due to shear layer manipulation and change in the axial location.

中文翻译：

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湍流圆形射流的尺度相关相干性分析，包括剪切层操作的影响

摘要 进行了两点热线测量以评估湍流圆形射流中相干结构的缩放。将与尺度相关的相干性分析应用于由两点同步轴向速度测量组成的数据集，热线位置之间具有不同的径向间隔，而参考热线固定在不同数据集中的中心线和两个偏离中心线的位置。在 R e D = 10000、20000 和 50000 以及一系列轴向位置 (3 ≤ x/D ≤ 25) 下进行测量。与尺度相关的相干分析揭示了在 λx/y0.5 ≈ 3.4 的轴向范围 15 ≤ x/D ≤ 25 上的涡流层次结构，在 R e D = 10000 处发现。纵横比在 R e D = 20000 时增加到 ≈ 3.9，在 R e D = 50000 时增加到 ≈ 4.7。这些值明显小于在湍流边界层中观察到的 = 14 的纵横比。涡流结构纵横比不受与喷嘴的轴向距离（在 x / D = 15 - 25 内）或控制环剪切层操作的影响。然而，由于剪切层操作和轴向位置的变化，发现最大涡流的随机径向跨度发生了变化。