円筒容器内循環流の縦渦崩壊に及ぼす固定円板サイズの影響(流体工学,流体機械)

概要

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A swirling flow produced in a cylindrical container by rotation of one endwall undergoes breakdown, i.e. a stagnation point followed by a recirculation zone of limited extent appears on the cylinder axis. The structure of the recirculation zones depends on not only rotational Reynolds number ΩR^2/v and aspect ratio H/R (H: working fluid height, R: cylinder radius) but also the core size and strength of the swirling flow. The purpose of this study is to reveal the nature of the vortex breakdown in a swirling flow produced in a closed or semi-closed cylindrical container. We used four different sizes of fixed endwall to change a swirl angle of the approaching flow to the recirculation zone. The experiments were carried out for the ranges of rotational Reynolds number and of aspect ratio where one or two recirculation zones were produced. By the flow visualization, the relation between the structure of the recirculation zone, the two parameters (rotational Reynolds number and aspect ratio) and fixed endwall sizes were revealed. By the numerical simulation, the relation of the recirculation zone and the Centrifugal and Coriolis forces was examined.
2002-10-25