硝子玉浮子の流水抵抗について-II : 保護網の各種要因変化による浮子の抵抗変化

概要

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In order to make clear how the resistance of glass floats covered with shelter-nets made of the two-hold twines varies with the difference of the net (e. i. materials, diameters of netting cord, size of mesh, and direction of the float), a series of measurements was pursued. The results obtained are summerized as follows: 1) The rate of increase of resistance due to the sheltering with net is proportional to the diameter of the netting cord. (Fig. 1) 2) The drag coefficient varies considerably, within the range of small meshes, with the difference of meshes. But it is practically constant when the size of mesh exceeds 7.5cm. (Fig. 2) 3) The difference of drag coefficient by kinds of materials of the shelter-net is insignificant practically. Namely, the drag coefficient of the floats covered with textiles having fluffy or rough surface, such as CREMONA and MANILA twines, is measured only 10% larger than that of SARAN and COTTON twines having smooth surface. 4) The drag coefficient of floats may be increased proportionally with angle which the direction of current makes with the axes passed through the two selvage-ends of the covering net. But the difference is about 10% at maximum, which is insignifficant practically.
公益社団法人日本水産学会の論文