| Research Abstract |
Filtration for solid-liquid multiphase flow
In the aspect ratio (Γ) from 0.5 to 1.0, various vortex modes have occurred in response to the influence of the boundary layer (Ekman boundary layer) which exists near the vertical boundary ends. Especially at Γ=0.6, there is a domain where a pair of vortex which exists in the vertical line make self-excited oscillation each other. When the Reynolds number increases further passing over the region of the self-excited oscillation, this pair of vortex stops vibrating and form the other pair of vortex, which stands in a line horizontally. This mode is called Twin vortex mode, which is stable but exists in the very limited Reynolds region. Further increase of Reynolds number after the region of the stable Twin vortex mode, it begins to oscillate again but in faster periods.
In the filtration experiment of Γ=3, the nylon particle, of which mean diameter is about 80μm and the specific gravity of 1.2, is used. In the experiment, the pressure drop is m
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easured with a pretty lower value as the rotation speed (Reynolds number) of the inner cylinder is increased. When the rotation speed is 0 (Re=0), most particle is accumulated on the filter in 7 minutes, and the test section becomes near transparently. From these results, the rotation of inner cylinder is much effective on reducing the pressure drop through the filtration process.
Cultivation of microorganism with Taylor vortex flow
Since it is difficult for treating a blood cell directly in the engineering laboratory, the similar vegetable photosynthesis microorganisms (chlorella and Spirulina) are used, and the fluid dynamic effect to cultivation by the Taylor vortex is investigated when Γ=1. As for the actual size, the diameter of the inner cylinder is 28mm, and the one of the outer 75mm, are selected respectively. The rotational speed is 150rpm and 250rpm, and the radius difference between the inner and outer cylinders is 25mm. The intensity of radiation and the cultivation conditions are same, and the cultivation time is about ten days.
In the higher rotational speed of 250rpm, sedimentation of the microorganism on the bottom plate is not observed, whereas the amount of sedimentation is seen in the lower rotational speed after the 3-day's cultivation. Even in the higher rotational speed, the cell of microorganism has not been destroyed, and the well-activated state is kept in the both rotational speeds. Especially a higher specific growth rate of the Chlorella is observed in the case of cultivation with the sedimentation on the bottom.
From these results, Chlorella microorganism seems to prefer the milder share flow condition to the high share flow with the larger rotational speed. Less
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