Plastron restoration for underwater superhydrophobic surface by porous material and gas injection
Plastron restoration for underwater superhydrophobic surface by porous material and gas injection
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DOI：
10.1016/j.colsurfa.2023.132319
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发表时间：
2023-08-29
影响因子：
5.2
通讯作者：
Ling，Hangjian
中科院分区：
文献类型：
--
作者：
Breveleri，Jordan;Mohammadshahi，Shabnam;Ling，Hangjian
恢复和维持水下超疏水表面 (SHS) 上的气体层（腹甲）对于 SHS 的实际应用至关重要，例如减少高雷诺数湍流中的摩擦阻力。在这项工作中，我们通过实验研究了基于多孔材料和气体注入的技术将水下 SHS 上的腹甲从完全润湿状态恢复的能力。 SHS 是通过在多孔钢板上喷涂商业超疏水涂层而创建的。实验中，SHS浸入静止液体中，独立控制注气压力和注气持续时间。通过高速摄像机检查 SHS 上气体层的状态。我们发现，腹甲恢复的表面积随着注气压力和注气持续时间的增加而增加，并且腹甲恢复过程涉及气泡形成、合并和分离。气泡脱离后表面留下一层气体。由于气泡合并，脱离的气泡的尺寸随着时间的推移而增加，并且当不再有气泡合并时变得稳定。增加气体注入压力导致更高的气体流速、更大的分离气泡尺寸和更快的腹甲修复。在最高压力下，腹甲在 0.3 秒内恢复，比原位气体生成方法更快。此外，我们发现通过水下 SHS 的气体流速可以用修正的达西定律来描述。我们的结果强调了使用多孔材料和气体注入来恢复腹甲的潜力，并使 SHS 的实际实施成为可能。
Restoring and maintaining the gas layer (plastron) on underwater superhydrophobic surface (SHS) is critical for the real-world application of SHS, such as reducing friction drag in high-Reynolds number turbulent flows. In this work, we experimentally investigated the capability of a technology based on porous material and gas injection to restore the plastron on an underwater SHS from a fully wetted state. The SHS was created by sprayed coating a commercial superhydrophobic coating on a porous steel plate. In the experiments, the SHS was immersed in stationary liquid, the gas injection pressure and gas injection duration were independently controlled. The status of gas layer on SHS was examined by a high-speed camera. We found that the surface area being restored with a plastron increased with increasing gas injection pressure and gas injection duration, and that the plastron restoration process involved bubble formation, merging and detachment. A layer of gas was left on the surface after bubble detachment. The size of the detached bubble increased with time due to bubble merging, and became stable when there was no more bubble merging. Increasing gas injection pressure led to higher gas flow rates, larger detached bubble sizes and faster plastron restorations. A plastron restoration within 0.3 s was achieved at the highest pressure, faster than the in-situ gas generation methods. Furthermore, we found that the gas flow rate through the underwater SHS can be described by a modified Darcy’s law. Our results highlighted the potential of using porous material and gas injection to restore the plastron and made possible the real-world implementation of SHS.