円錐網の抗力係数とレイノルズ数

概要

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A fluid dynamic of midwater trawl and codend are associated with a flow velocity inside the net. This study investigates the relationship between drag coefficient of conical nets and Reynolds number which concerns with a flow velocity inside the net. In order to measure the drag of conical nets, twenty models of different open area ratios, which composed five kinds of twisted knotless nettings and four kinds of hanging angles, were tested in the flume tank of Kagoshima University. The mouth of each net was attached to a circular shaped frame to maintain geometric feature, and the nets were set into the flume tank normal to the flow direction. The velocity was monitored by a supersonic digital current meter which is installed in the flume tank, and the drag was measured using a three-component load cell. Measured values were stored in a data file of a computer for analysis. If uniform hanging angle is the significant factor affecting the drag of the conical nets depended on the open area ratio. When the representative velocity U_m/ β and representative length d were used as a characteristic velocity inside the net. And scale, a more general correlation between the drag coefficient and the Reynolds number are found using the exponential linear regression. C_D' was found to be C_D'= 18.88 Re'^<-0.63>.
鹿児島大学の論文
1996-12-24