Progress in Turbulence VII
Progress in Turbulence VII
复制标题
湍流 VII 的进展
DOI：
10.1007/978-3-319-57934-4_30
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Breda M
中科院分区：
文献类型：
--
作者：
Breda M
本文研究了初始条件对轴对称湍流射流近场流动物理和自相似演化的影响。近场大尺度相干结构是借助于非圆几何，如正方形和分形出口来操纵的。采用平面PIV和热线风速仪对流场进行了空间和时间分析。尽管由于出口几何形状的不同，近场流动物理发生了很大的变化，但发现所有喷流之间向自相似方向的演化是相似的。此外，在射流出口下游24到26个当量直径之间存在非平衡耗散，在那里平均速度和雷诺应力是自相似的，这表明流动的微尺度比以前认为的更远地恢复了经典的标度定律。
In this paper, the role of the initial conditions in affecting the flow physics in the near-field, and the evolution towards self-similarity, of an axisymmetric turbulent jet is examined. The near-field large scale coherent structures are manipulated with the aid of noncircular geometries, such as square and fractal exits. Planar PIV and hot-wire anemometry are deployed to study the flow both spatially and temporally. Despite the significant alteration of the near-field flow physics due to the different exit geometries, it is found that the evolution towards self-similarity is comparable between all jets. Moreover, non-equilibrium dissipation is found between 24 and 26 equivalent diametersdownstream of the jet exit where mean velocity and Reynolds stresses are self-similar, suggesting the microscales of the flow take much further than previously thought to regain the classical scaling laws.