Liquid flow behaviour of bubble columns

概要

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Liquid flow behaviour of a bubble column was investigated experimentally with emphasis on its turbulent motion. Pictures of tracer particles suspended in liquid were photographed with a high speed cinecamera on colour films avoiding the confusion of images of particles and bubbles. Trajectory of particles on the films were followed by a film analyzer and fluctuating velocities of tracers (as liquid) were obtained. Liquid flow behaviour was then analyzed statistically for the terms of the mean liquid velocity distribution, the fluctuating velocity distribution, the autocorrelation curve, the turbulent scale and so on. 1) Liquid flow in a bubble column showed the upward flow in the core with violent eddy motion and downward flow near the wall. The radial distribution of axial mean liquid flow velocity was consistent with Miyauchi's model and the radial mean velocity was neary equal to zero. 2) Liquid velocity fluctuates greatly in a short time as indicated by the intensity of turbulence of axial liquid velocity which was about 90% at the center. 3) The eddy scale in the center was about 1/6th-1/7th of column diameter in radial direction and about one half in axial direction. 4) In the down flow region near the wall, a large fluctuation with a characteristic periodicity was observed in the periodgram. 5) The liquid flow behaviour was not much influenced by liquid viscosity 1-12 c. p.
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