微纳结构超疏水表面的湍流减阻机理研究

超疏水表面的优异性质使其在现代生活和工业生产中具有十分广泛的潜在应用价值. 本文采用了碳纳米管缠绕技术和聚氟硅氧烷疏水化处理方法制备了具有二级微纳米结构的超疏水表面. 测量了由该超疏水表面构建的槽道中的流动压降,将其与普通表面构建的槽道内的流动压降进行比较,发现在层流情况下,流动阻力减小最多达到了22.8%. 在湍流的情况下,超疏水表面的减阻比例约为53.3%,减阻效果比层流更加明显.利用PIV (particle image velocimetry) 技术测量了具有超疏水表面的槽道内的速度场,通过超疏水表面速度滑移和湍动脉动场信息,分析了湍流减阻效果比层流更加明显的物理机制.

DRAG REDUCTION IN TURBULENT FLOWS OVER SUPERHYDROPHOBIC SURFACES WITH MICRO-NANO TEXTURES

The superhydrophobic surfaces have a very wide range of potential applications in the modern life and industrial production due to their excellent properties. In this paper, a kind of superhydrophobic surface was fabricated by pasting micro-nano particles onto an aluminium or PMMA (polymethylmethacrylate) substrate. The micro-nano particles were obtained by carbon nanotubes winding technology and hydrophobic processing. The pressure drop measurements were carried out in the channel with superhydrophobic surfaces above. Compared with the common surface channel, the flow resistance decreases by about 22.8% at most in the laminar flow. In the turbulent flow, the drag reduction can reach 53.3%. The velocity field in the channel with such superhydrophobic surfaces was measured by particle image velocimetry (PIV) technology. Through the slip velocities in the superhydrophobic surface and the turbulent fluctuations, the physical mechanism is revealed to show that the turbulent friction reduction effects are apparently better than in cases of laminar flows.