Coupled Bionic Drag-Reducing Surface Covered by Conical Protrusions and Elastic Layer Inspired from Pufferfish Skin
Coupled Bionic Drag-Reducing Surface Covered by Conical Protrusions and Elastic Layer Inspired from Pufferfish Skin
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DOI：
10.1021/acsami.2c08513
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发表时间：
2022-07-10
影响因子：
9.5
通讯作者：
Zhang, Yaosheng
中科院分区：
文献类型：
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作者：
Feng, Xiaoming;Fan, Dongliang;Zhang, Yaosheng
摘要：受到河豚鱼皮肤上锥形刺和弹性层的减阻特性的启发，正在进行重要的努力，以建立合理的多重减阻策略，用于开发新的海洋工程材料。在本工作中，一个新的减阻表面（CPES）覆盖的圆锥形突起（稀疏的“k型”，粗糙的高度k+ = 13-15）和弹性层通过混合方法，结合烧结和涂层工艺在铜基板上构建。通过流变仪和粒子图像测速仪（PIV）实验研究了所制备的CPES仿生表面的减阻特性。为全面研究其减阻机理，采用多孔铜基底（PCS）、铜基底（CS）、锥形凸起树脂基底（CPRS）和锥形凸起多孔铜基底（CPPCS）进行对比分析。在层流条件下，我们发现锥形突起结构和弹性表面耦合的润湿性影响CPES样品的减阻性能（7-8%），界面产生滑移以降低粘滞阻力。在湍流条件下，CPES仿生表面的减阻率为11.5-17.5%。这种行为是由两个并发机制实现的：（i）作为涡流发生器的锥形突起增加了涡流的数量和尾流效应，使得下游条带能够更快地移动，减少粘性阻力;（ii）锥形突起元件破碎并提升大尺度涡流，以产生许多具有低能量的小尺度涡流，有效地削弱扰动和动量交换。另外，在砂纸磨损和水流冲刷测试后，弹性层显示出在铜基底上的高附着力和稳定性。通过烧结方法形成的铜基底表面也覆盖有致密的多孔结构，这赋予弹性层和锥形突起优异的组合鲁棒性。我们的研究结果不仅揭示了鲁棒减阻表面的设计新的光，但也提供了新的途径，在海洋应用领域的水下减阻。
ABSTRACT: Inspired by the drag-reducing properties of the cone-like spines and elastic layer covering the pufferfish skin, important efforts are underway to establish rational multiple dragreducing strategies for the development of new marine engineering materials. In the present work, a new drag-reducing surface (CPES) covered by conical protrusions (sparse "k-type" with rough height k+ = 13-15) and an elastic layer are constructed on copper substrate via a hybrid method, combining the sintering and coating processes. The drag-reducing feature of the prepared CPES biomimetic surface is achieved by rheometer and particle image velocimetry (PIV) experiments. To comprehensively investigate its drag reduction mechanism, the porous copper substrate (PCS), copper substrate (CS), conical protrusion resin substrate (CPRS), and conical protrusion porous copper substrate (CPPCS) were used for a comparative analysis. In laminar flow, we discovered that the conical protrusion structure and wettability of the elastic surface coupling affect the CPES sample's drag-reducing performance (7-8%) and that the interface produced slip to reduce the viscous drag. In turbulent flow, the CPES biomimetic surface exhibits an 11.5-17.5% drag-reducing performance. Such behavior was enabled by two concurrent mechanisms: (i) The conical protrusions as vortex generators enhance the number of vortices and the wake effect, enabling faster movement of downstream strips, reducing viscous drag; (ii) The conical protrusion elements break and lift large-scale vortices to produce numerous small-scale vortices with low energy, effectively weakening perturbations and momentum exchange. Additionally, the elastic layer shows high adhesion and stability on copper substrate after sandpaper abrasion and water-flow erosion tests. The copper substrate surface formed by the sintering method is also covered with dense porous structures, which gives the elastic layer and conical protrusions excellent combined robustness. Our findings not only shed new light on the design of robust drag-reducing surfaces but also provide new avenues for underwater drag reduction in the field of marine applications.