기울어진 미세 텍스쳐 표면에 충돌하는 단일 액적의 퍼짐 특성

초록

The present study investigated experimentally the spreading characteristics of a single liquid impinging on the inclined micro-textured aluminum (Al 6061) surfaces manufactured by using a micro computerized numerical control (μ-CNC) milling machine. The textured surfaces were composed of patterned micro-holes (diameter of 125 μm and depth of 125 μm). In our experiment, the de-ionized (DI) water droplet of 4.3 μl was impinged normally on the non-textured and textured surfaces at two different Weber numbers, and the droplet impinged on the inclined surfaces with different angles. A high speed camera was used to capture sequential digital images for measurement of the maximum spreading distance. It was found that for the textured surface, the measured apparent equilibrium contact angle (ECA) increased up to 105.8°, higher than the measured ECA of 87.6° for the non-textured (bare) surface. In addition, it is conjectured that the spreading distance decreased because of a liquid penetration during droplet spreading through the holes, the increase in hydrophobicity, and viscous dissipation during impact process.

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