Drag reduction properties of superhydrophobic mesh pipes
Drag reduction properties of superhydrophobic mesh pipes
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DOI：
10.1088/2051-672x/aa793b
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发表时间：
2017-07
期刊：
影响因子：
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通讯作者：
Nicasio R. Geraldi;L. Dodd;B. Xu;G. Wells;D. Wood;M. Newton;G. McHale
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文献类型：
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作者：
Nicasio R. Geraldi;L. Dodd;B. Xu;G. Wells;D. Wood;M. Newton;G. McHale
即使最近对超疏水表面进行了广泛的研究，在管道内壁上制造这种表面仍然具有挑战性。在这项工作中，我们报告了一个方便的双层管道设计，使用薄的超疏水金属网形成一个管，支持内另一个管道。构建了一个流动系统来测试所制造的双层管道，该系统允许不同的恒定流速的水通过管道，同时测量压差，由此计算阻力系数（ε）和雷诺数（Re）。雷诺数（Re）范围为750-10 000，在层流和部分湍流状态下，光滑玻璃管的预期值均被发现。还在类似的范围（750 < Re < 14 000）内测量了通过没有超疏水涂层的普通网格的流量。在施加超疏水涂层之后，发现对于4000 < Re < 14 000的情况下，Re小于未涂覆的网的Re，但大于相同直径的光滑玻璃管的Re。这表明，与普通网格相比，超疏水网格可以支撑腹板并提供减阻，然而，腹板随着使用而逐渐被破坏，特别是在较高的流速下。
Even with the recent extensive study into superhydrophobic surfaces, the fabrication of such surfaces on the inside walls of a pipe remains challenging. In this work we report a convenient bi-layered pipe design using a thin superhydrophobic metallic mesh formed into a tube, supported inside another pipe. A flow system was constructed to test the fabricated bi-layer pipeline, which allowed for different constant flow rates of water to be passed through the pipe, whilst the differential pressure was measured, from which the drag coefficient (ƒ) and Reynolds numbers (Re) were calculated. Expected values of ƒ were found for smooth glass pipes for the Reynolds number (Re) range 750–10 000, in both the laminar and part of the turbulent regimes. Flow through plain meshes without the superhydrophobic coating were also measured over a similar range (750 < Re < 14 000). After applying the superhydrophobic coating, ƒ was found for 4000 < Re < 14 000 and was found to be less than that of an uncoated mesh, but greater than that of a smooth glass pipe of the same diameter. This demonstrates that a superhydrophobic mesh can support a plastron and provide a drag reduction compared to a plain mesh, however, the plastron is progressively destroyed with use and in particular at higher flow rates.