A25-128 EFFECT OF THE MICRO-STRUCTURE OF HIGHLY WATER-REPELLENT SURFACE ON DRAG REDUCTION
スポンサーリンク
概要
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We investigated the drag reduction phenomena on highly water repellent surfaces, which have micron to sub-millimeter order of projections. In present study, the drag reduction is estimated by means of friction coefficients for laminar flow in 2mm×8mm rectangular duct, where the bottom surface in the tested section consist of the water-repellent micro-structured surface. The surfaces were also microscopically observed in water flow to be ensured that there exist air layers on the surfaces that avoid the contact between liquid and solid surfaces so that the drag reduction may occur. The sizes and pitch of the projections on the surfaces were treated as the main parameters of the present work. Among three different surfaces tested, the one that have the largest concavo-convex structure caused reduction of friction coefficient of 2%. The surface with thinner and sparser projections couldn't hold the air layer that seems to be the cause of drag reduction, while the water droplet on the surface exhibited highest contact angle. It can be said that the ability to hold the air layer in water depends on both the size and the ratio of concavo-convex structure.
- 一般社団法人日本機械学会の論文
- 2003-11-30
著者
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Hasegawa Masato
Dept. Of Human & Mechanical Systems Engineering Kanazawa University
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Koyama Naomichi
Dept. of Human & Mechanical Systems Engineering Kanazawa University
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Ryutaki Kozo
Dept. of Human & Mechanical Systems Engineering Kanazawa University
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Ueno Hisanori
Dept. of Human & Mechanical Systems Engineering Kanazawa University
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Ryutaki Kozo
Dept. Of Human & Mechanical Systems Engineering Kanazawa University
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Ueno Hisanori
Dept. Of Human & Mechanical Systems Engineering Kanazawa University
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Koyama Naomichi
Dept. Of Human & Mechanical Systems Engineering Kanazawa University