This paper aims to study the drag reduction of a superhydrophobic nanocomposite coating for engineering applications. In the method developed, a suspension of hydrophobic silica nanoparticles in PDMS/toluene solution was prepared. Then a spray-deposition method is used to deposit a layer of nanocomposite composed of PDMS/hydrophobic silica nanoparticles on the surface. After curing the samples at 100 °C for 1 h the nanocomposite coating was prepared. The surface morphology of the coating was characterized by scanning electron microscopy and static water contact angle measurement. The superhydrophobic properties of fabricated surfaces are investigated through different PDMS/hydrophobic silica nanoparticles ratios. It was found that the presented nanocomposite coating method was an effective technology which was suitable to form large-area superhydrophobic coating with a water droplet (5 μL) roll-off angle of less than 5°. The hydrostatic pressure test showed that the Cassie−Baxter state of the fabricated coating is stable in front of the applied pressure up to 50 kPa. Drag reduction tests showed that the air-layer placed at the water-superhydrophobic interface was stable in front of wall shear stress up to 11 Pa. The maximum drag reduction and slip length were measured about 25% and 70 μm, respectively.

本文旨在研究用于工程应用的超疏水纳米复合涂料的减阻性能。在开发的方法中，制备了疏水性二氧化硅纳米粒子在PDMS /甲苯溶液中的悬浮液。然后使用喷涂法在表面沉积一层由PDMS /疏水性二氧化硅纳米粒子组成的纳米复合材料层。将样品在100°C固化1小时后，制备了纳米复合涂层。通过扫描电子显微镜和静态水接触角测量来表征涂层的表面形态。通过不同的PDMS /疏水性二氧化硅纳米粒子比率研究了人造表面的超疏水性。发现所提出的纳米复合涂层方法是一种有效的技术，其适合于形成水滴（5μL）滚落角小于5°的大面积超疏水涂层。静水压力测试表明，在施加压力高达50 kPa之前，所制造涂层的Cassie-Baxter状态是稳定的。减阻测试表明，放置在水-超疏水性界面处的空气层在壁面剪应力前稳定至11 Pa。最大减阻和滑移长度分别约为25％和70μ米，分别。