张照,许晓慧,黄金艺,牟震林,苑伟政,何洋,吕湘连.厘米尺度亲疏水间隔表面水下气膜维持效果及机理研究[J].表面技术,2023,52(12):188-196.
ZHANG Zhao,XU Xiao-hui,HUANG Jin-yi,MU Zhen-lin,YUAN Wei-zheng,HE Yang,LYU Xiang-lian.Underwater Gas Film Maintenance Effect and Mechanism of Centimeter-scale Alternant Hydrophilic and Superhydrophobic Surface[J].Surface Technology,2023,52(12):188-196 |
| 厘米尺度亲疏水间隔表面水下气膜维持效果及机理研究 |
| Underwater Gas Film Maintenance Effect and Mechanism of Centimeter-scale Alternant Hydrophilic and Superhydrophobic Surface |
| 投稿时间：2023-08-05 修订日期：2023-11-10 |
| DOI：10.16490/j.cnki.issn.1001-3660.2023.12.017 |
| 中文关键词: 亲疏水间隔表面 厘米级气膜 主动供气 气膜维持 |
| 英文关键词:alternant hydrophilic and superhydrophobic surfaces centimeter-scale air film active air supply air film maintenance |
| 基金项目:翼型、叶栅空气动力学重点实验室稳定支持经费项目(61422010102，6142201200403) |
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| Author | Institution |
| ZHANG Zhao | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| XU Xiao-hui | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| HUANG Jin-yi | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| MU Zhen-lin | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| YUAN Wei-zheng | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| HE Yang | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
| LYU Xiang-lian | Key Laboratory of Micro/nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi'an 710072, China |
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| 中文摘要: |
| 目的 面向水下航行器减阻技术挑战，克服现有全超疏水表面气膜维持效果较差的问题，提出了厘米尺度的亲疏水间隔表面水下气膜维持思路，以获得更高的水下减阻性能。方法 采用k-ω湍流模型对厘米尺度的亲疏水间隔表面、全超疏水表面进行了流速0.5 m/s的水流冲刷模拟仿真，其中亲疏水间隔表面设定凹槽中的超疏水表面接触角为165°，亲水间隙接触角为45°;全超疏水表面的接触角均为165°。随后基于仿真结果，对厘米尺度的2种表面在不同水流速度和供气条件下进行水流冲刷实验，研究了这2种表面在不同实验条件下的气膜形状变化。结果 仿真结果显示亲水间隙的存在使凹槽内的气体受到钉扎束缚作用，可以实现气膜维持。实验结果显示在厘米尺度下，全超疏水表面在流速为0.55 m/s的条件下气膜维持情况较好，但在流速达到0.94 m/s，雷诺数为Re=14 030时，实验部分的流动状态为湍流状态，凹槽内气膜覆盖的面积时有变化，能覆盖的面积一般不超过凹槽面积的50%，很难维持完整的气膜;而在0~1.2 m/s的流速范围内，亲疏水间隔表面能够在超疏水区域始终维持稳定气膜表面，具有好的气膜维持效果。结论 相比均匀的全超疏水表面，亲疏水间隔表面能够因其前后接触角差异为气膜提供最大的束缚力，具有良好的气膜维持性能;由于其能束缚的气膜厚度更大，表面速度滑移更大，所以能产生更好的水下减阻效果。 |
| 英文摘要: |
| The unique surface properties of superhydrophobic surfaces make them capable of sealing the air film underwater. With excellent underwater drag reduction effects, it has become an international research hotspot. The maintenance of air films on superhydrophobic surfaces is the key to its application in underwater drag reduction. Some studies show that the air film at large scales has a good drag reduction effect. However, previous studies have mostly focused on the maintenance of air films at millimeter and smaller scales, and the maintenance of air films at centimeter scales has not yet been reported. In this paper, in order to overcome the problems of poor air film maintenance on existing fully superhydrophobic surfaces and insufficient drag reduction effect of millimeter-scale air films, the idea of centimeter-scale air film maintenance on alternant hydrophilic and superhydrophobic surfaces underwater was proposed to obtain high drag reduction performance underwater. Firstly, the k-ω turbulence model was used to simulate the water scouring of the centimeter-scale alternant hydrophilic and superhydrophobic surface and fully superhydrophobic surfaces at a flow rate of 0.5 m/s, in which the contact angle of the superhydrophobic surfaces in the groove on the alternant hydrophilic and superhydrophobic surface was set to 165°, and the hydrophilic gaps were set to 45°. The contact angles of the fully superhydrophobic surfaces were all set to 165°. Then, based on the simulation results, water scouring experiments were carried out on the two surfaces at a centimeter scale under different water flow rates and air supply conditions, and the changes in the air film shapes of the two surfaces under different experimental conditions were investigated. The simulation results showed that a hydrophilic gap made the gas in the groove subject to a pinning and binding effect, which allowed gas film maintenance. The experimental results showed that the air film on the fully superhydrophobic surface at the centimeter scale was maintained better at a flow rate of 0.55 m/s. However, when the flow rate reached 0.94 m/s, with the calculated Reynolds number ofRe=14 030, the flow state in the experimental section was turbulent, the area covered by the air film in the groove changed from time to time, and the area that could be covered was generally no more than 50% of the area of the groove, which made it difficult to maintain the complete air film. While in the flow rate range of 0~1.2 m/s, the alternant hydrophilic and superhydrophobic surface and hydrophobic spacer surfaces could maintain a stable air film surface in the superhydrophobic region, which had a good effect on maintaining the air film. Based on the experimental results and mechanism analysis, it is concluded that, compared with the fully superhydrophobic surface, the alternant hydrophilic and superhydrophobic surface can provide the maximum binding force to the air film due to the difference in advancing and receding contact angle of the alternant hydrophilic and superhydrophobic surface, which has good air film maintenance performance. The greater thickness of the air film and the greater surface velocity slip result in better underwater drag reduction. |
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