沟槽型微纳复合结构表面的制备与减阻性能研究

Preparation and Drag Reduction Performance of Grooved Micro-Nano Composite Structure Surface

沟槽微结构减阻与疏水表面减阻是两种有效的水下减阻技术。将两种典型的减阻技术进行联合协同,在聚对苯二甲酸乙二醇酯-1,4-环己烷二甲醇酯(PETG)基底表面采用激光微刻方法构筑微米级沟槽结构,采用二步喷涂法先后在微沟槽表面覆盖环氧树脂层与改性的纳米SiO2颗粒,从而实现沟槽型微纳复合结构表面的制备。利用接触角测量仪、体视显微镜、拖曳式摩擦阻力测试设备对复合结构表面的润湿性、水下气膜状态及水下减阻性能进行表征。结果表明,沟槽型微纳复合结构表面为超疏水表面,液滴在该表面处于“Cassie-Baxter”润湿状态;在水下,复合结构表面具有束缚大尺寸气膜的能力,气膜驻留于表面沟槽之中且促使了表面的水下减阻效果的产生;对比单纯的沟槽微结构表面与喷涂SiO2颗粒光滑表面,制得的沟槽型复合结构表面在沿垂直于沟槽方向运动时最大减阻率可达20.82%,同时表面气膜的稳定性也最佳。

Grooved microstructure drag reduction and hydrophobic surface drag reduction are two effective underwater drag reduction techniques.The two typical drag reduction methods were combined and synergized.After the micro-scale trench structure was constructed by laser micro-en-graving technology on the surface of the PETG substrate,the epoxy resin layer and the modified nano-scale SiO2 particles were successively covered on the surface of the micro-groove by a two-step spraying method,so as to realize the preparation of the surface of grooved micro-nano composite structure.The surface wettability,underwater gas film state and underwater drag reduction performance of the prepared surfaces were analyzed by contact angle measuring instrument,stereo microscope and dragging friction resistance testing equipment.Results showed that the surface of the grooved micro-nano composite structure is a superhydrophobic surface,and the surface droplets are in the‘Cassie-Baxter’wet state.When underwater,the surface of the composite structure has the ability to bind a large-scale gas film,and the gas film resides in the sur-face grooves and promotes the underwater drag reduction effect of the surface.Comparing the surface of a simple groove microstructure with a smooth surface coated with SiO2 particles,the maximum drag reduction rate can reach 20.82%when the surface moves along the diction prepen-dicular to the grooves.Meanwhile,the stability of surface air film is also optimal.