Experimental study on drag-reduction effect due to sinusoidal riblets in turbulent channel flow
Experimental study on drag-reduction effect due to sinusoidal riblets in turbulent channel flow
复制标题
DOI：
10.1007/s00348-014-1828-z
复制
发表时间：
2014-10-01
影响因子：
2.4
通讯作者：
Murata, A.
中科院分区：
文献类型：
--
作者：
Sasamori, M.;Mamori, H.;Murata, A.
在充分发展的槽道湍流中，对三维正弦波纹面的减阻效果进行了实验研究。肋片相邻壁面的横向间距在流向上呈正弦变化。当散体雷诺数为3,400时，得到的最大总减阻率约为12%。利用二维粒子图像测速仪，在速度场中分析了正弦波纹面的流动结构。将速度场与平面上的相应流动进行了比较。通过路径线和雷诺剪应力分析发现，这种减阻机理与二维肋的减阻机理相似。不同的是，现在的肋片在扩张和收缩区域分别诱导了向下和向上的流动，从而防止了涡流冲击到肋片横向间距较大的底壁。因此，这种正弦沟槽的润湿面积比二维沟槽的小，具有较高的减阻效果。
The drag-reduction effect of a three-dimensional sinusoidal riblet surface is experimentally evaluated in a fully developed turbulent channel flow. The lateral spacing of the adjacent walls of the riblet is varied sinusoidally in the streamwise direction. The obtained maximum total drag-reduction rate is approximately 12 % at a bulk Reynolds number of 3,400. The flow structure over the sinusoidal riblet surface is also analyzed in the velocity field by using two-dimensional particle image velocimetry. The velocity field is compared with the corresponding flow over a flat surface. It is found through pathlines and Reynolds shear stress analyses that the drag-reduction mechanism is similar to those of two-dimensional riblets. A different point is that the present riblet respectively induces a downward and upward flows in the expanded and contracted regions, which prevent vortices from hitting the bottom wall with wider lateral spacing of the riblet. In consequence, the wetted area of the present sinusoidal riblet is smaller than those of two-dimensional riblets, resulting in the high drag-reduction effect.