超はっ水性回転円板のニュートン流体における摩擦抵抗の低減について〔流体工学, 流体機械〕

概要

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By use of a highly water-repellent coating wall, a new type of drag reduction for a rotating disk in a Newtonian fluid has been found experimentally. Measurements were carried out to investigate the torque of rotating disks with a highly water-repellent wall and with a smooth aluminum wall. The clearance between the disk and the wall was varied, at 5,10,and 20mm. The tested fluids were tap water and aqueous solutions of glycerin at concentrations of 30 and 40wt%. The experimental data of the frictional moment of the rotating disk obtained using the highly water-repellent wall were smaller than those of the smooth aluminum rotating disk. It was shown that the maximum drag reduction ratio was about 45% in a 40wt% glycerin solution at about Re=10^5. and the viscosity of the fluid has a slight effect on the drag reduction.
1997-08-25