Superhydrophobic turbulent drag reduction as a function of surface grating parameters
Superhydrophobic turbulent drag reduction as a function of surface grating parameters
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DOI：
10.1017/jfm.2014.151
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发表时间：
2014-05-01
影响因子：
3.7
通讯作者：
Kim, Chang-Jin CJ
中科院分区：
文献类型：
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作者：
Park, Hyungmin;Sun, Guangyi;Kim, Chang-Jin CJ
尽管在小尺度层流中已证实存在滑移流且成功实现了减阻（DR），但由于在湍流中实验结果零星且不一致，超疏水（SHPo）减阻的全面影响仍存疑问。在此我们报道了一组系统的无偏差减阻数据，这些数据是通过在湍流边界层（TBL）流中的同一时间和位置测量超疏水表面和光滑表面的表面摩擦阻力而获得的。每个整体式样品由一个超疏水表面和一个由挠性弹簧悬挂的光滑表面组成，全部通过光刻微加工从一个2.7×2.7平方毫米的硅芯片上切割出来。流动测试能够对超疏水表面上的气膜进行连续监测，因此减阻数据是真实且一致的。一组具有精确轮廓的超疏水样品揭示了光栅参数对湍流减阻的影响，经测量其减阻效果高达约75%。
Despite the confirmation of slip flows and successful drag reduction (DR) in small-scaled laminar flows, the full impact of superhydrophobic (SHPo) DR remained questionable because of the sporadic and inconsistent experimental results in turbulent flows. Here we report a systematic set of bias-free reduction data obtained by measuring the skin-friction drags on a SHPo surface and a smooth surface at the same time and location in a turbulent boundary layer (TBL) flow. Each monolithic sample consists of a SHPo surface and a smooth surface suspended by flexure springs, all carved out from a 2.7 x 2.7 mm(2) silicon chip by photolithographic microfabrication. The flow tests allow continuous monitoring of the plastron on the SHPo surfaces, so that the DR data are genuine and consistent. A family of SHPo samples with precise profiles reveals the effects of grating parameters on turbulent DR, which was measured to be as much as similar to 75 %.