Turbulent drag reduction of boundary layer flow with non-ionic surfactant injection
Turbulent drag reduction of boundary layer flow with non-ionic surfactant injection
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DOI：
10.1017/jfm.2014.225
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发表时间：
2014-05
影响因子：
3.7
通讯作者：
Shinji Tamano;T. Kitao;Yohei Morinishi
中科院分区：
文献类型：
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作者：
Shinji Tamano;T. Kitao;Yohei Morinishi
摘要我们实验研究了在减阻湍流边界层流动中注入非离子表面活性剂溶液后湍流动力学的流向变化，该溶液主要由油基二甲基氧化胺组成。我们专注于注射（即非均相）和预混（即均相）的表面活性剂溶液，其中的最大减阻率为50%是相同的，在最下游的位置为两种情况下的湍流统计的比较。湍流统计，如流向和壁正常的湍流强度，壁正常的配置文件，似乎是显着不同的非均质和均质表面活性剂的解决方案。然而，这些最大值和壁面法线位置的流向变化基本上彼此相似，除了流向湍流强度的最大值，其不是由减阻量来安排的，并且还取决于由于外部和内部变量而引起的归一化。这种复杂的流向湍流强度特性是由平行于壁面的近壁分层结构的形成引起的。对于非均质和均质表面活性剂溶液，减阻比的流向变化对应于壁单元中的平均速度和流向和壁法向湍流强度最大值的壁法向位置，具有外部和内部缩放。与雷诺切应力不同，流向湍流脉动和壁面法向湍流脉动的相关系数与减阻率有很好的相关性。我们提出了合理的图片发展的湍流结构，如发夹涡和低速条纹的减阻湍流边界层在非均质和均质表面活性剂的解决方案，这是全面来自目前的一套实验测量，如流动可视化，平面激光诱导荧光，在流向和壁面法向平面以及流向和展向平面上的双分量激光多普勒测速仪和粒子图像测速仪。
Abstract We experimentally investigated streamwise variations of turbulent dynamics in drag-reducing turbulent boundary layer flows following the injection of non-ionic surfactant solutions, which mainly consisted of oleyldimethylamine oxide. We focus on the comparison of turbulence statistics between injected (i.e. heterogeneous) and premixed (i.e. homogeneous) surfactant solutions, in which the maximum drag reduction ratio of 50 % is the same at the most downstream position for both cases. The wall-normal profiles of turbulence statistics, such as streamwise and wall-normal turbulence intensities, seem to be noticeably different between heterogeneous and homogeneous surfactant solutions. However, streamwise variations in these maxima and the wall-normal locations are essentially similar to one another, except for the maximum of streamwise turbulence intensity, which is not arranged by the amount of drag reduction and is also dependent on the normalization due to outer and inner variables. Such complex behaviour of streamwise turbulence intensity would be caused by the formation of near-wall layered structures that are parallel to the wall. For both heterogeneous and homogeneous surfactant solutions, the streamwise variation in the drag reduction ratio corresponds well to those of the mean velocity in wall units and the wall-normal locations of maxima of streamwise and wall-normal turbulence intensities with both outer and inner scaling. Unlike the Reynolds shear stress, the correlation coefficient of the streamwise and wall-normal turbulent fluctuations is correlated well with the drag reduction ratio. We present plausible pictures of the development of turbulence structures such as hairpin vortices and low-speed streaks for the drag-reducing turbulent boundary layer in heterogeneous and homogeneous surfactant solutions, which are comprehensively derived from the present set of experimental measurements such as flow visualization, planar laser-induced fluorescence, two-component laser-Doppler velocimetry and particle image velocimetry on the streamwise and wall-normal plane and the streamwise and spanwise plane.