Cao Yanlin, Liu Xiaochao, Zhang Liangpei, Wu Yanchen, You Chenxi, Li Hongyuan, Duan Huiling, Huang Jianyong, Lv Pengyu
State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Engineering Science, BIC-ESAT, College of Engineering, Peking University, Beijing 100871, China.
Laoshan Laboratory, Qingdao 266237, People's Republic of China.
ACS Appl Mater Interfaces. 2024 Apr 3;16(13):16973-16982. doi: 10.1021/acsami.3c18905. Epub 2024 Mar 19.
Superhydrophobic surfaces (SHS) offer versatile applications by trapping an air layer within microstructures, while water jet impact can destabilize this air layer and deactivate the functions of the SHS. The current work presents for the first time that introducing parallel hydrophilic strips to SHS (SHS-s) can simultaneously improve both water impalement resistance and drag reduction (DR). Compared with SHS, SHS-s demonstrates a 125% increase in the enduring time against the impact of water jet with velocity of 11.9 m/s and a 97% improvement in DR at a Reynolds number of 1.4 × 10. The key mechanism lies in the enhanced stability of the air layer due to air confinement by the adjacent three-phase contact lines. These lines not only impede air drainage through the surface microstructures during water jet impact, entrapping the air layer to resist water impalement, but also prevent air floating up due to buoyancy in Taylor-Couette flow, ensuring an even spread of the air layer all over the rotor, boosting DR. Moreover, failure modes of SHS under water jet impact are revealed to be related to air layer decay and surface structure destruction. This mass-producible structured surface holds the potential for widespread use in DR for hulls, autonomous underwater vehicles, and submarines.
超疏水表面（SHS）通过在微结构中捕获空气层而具有多种应用，而水射流冲击会破坏该空气层并使超疏水表面的功能失效。当前的研究首次表明，在超疏水表面（SHS-s）上引入平行的亲水性条带可以同时提高抗水冲击性和减阻（DR）性能。与超疏水表面相比，SHS-s在承受速度为11.9 m/s的水射流冲击时，持久时间增加了125%，在雷诺数为1.4×10时，减阻性能提高了97%。关键机制在于相邻三相接触线对空气的限制作用增强了空气层的稳定性。这些接触线不仅在水射流冲击期间阻碍空气通过表面微结构排出，从而捕获空气层以抵抗水冲击，而且还防止空气在泰勒-库埃特流中因浮力而向上漂浮，确保空气层在整个转子上均匀分布，提高减阻性能。此外，还揭示了超疏水表面在水射流冲击下的失效模式与空气层衰减和表面结构破坏有关。这种可大规模生产的结构化表面在船体、自主水下航行器和潜艇的减阻方面具有广泛应用的潜力。
