容器回転を伴う円筒容器内の渦崩壊に関する研究(流体工学,流体機械)

概要

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Experimental and numerical studies on the vortex breakdown in a differentially-rotating cylindrical container are presented. Flow depends on the rotational Reynolds number Re_？=R^2(Ω_t-Ω_sb)/v based on the relative angular velocity, the aspect ratio of the container H/R and the Rossby number Ro=|Ω_t-Ω_sb|/2Ω_sb or the Ekman number Ek=v/(2Ω_sb R^2), here v is kinematic viscosity of working fluid, Ω_tand Ω_sb respectively angular velocities of top endwall and container (sidewall and bottom endwall), H fluid depth, and R radius of the endwalls. In despite of the rotation of the container was very small compared with that of the top endwall, flow was quite different from the case without rotation of the container. As Ek increased, the breakdown bubble moved toward downstream for the case of counter-rotation (Ω_tΩ_sb<0), whereas the breakdown bubble moved toward upstream for the case of co-rotation (Ω_t-Ω_sb>0). The boundaries of vortex breakdown for the cases of non-rotation, co-rotation and counter-rotation of the container were shown in the flow regime map. The necessary condition for the appearance of vortex breakdown which proposed by Brown and Lopez was applied to the present cases. Consequently, the influence of Coriolis force on the necessary condition was made clear for the cases of co-rotation and counter-rotation.
2002-06-25