| Project/Area Number |
15360096
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
WATANABE Masao Kyushu University, Faculty of Engineering, Associate Professor, 大学院・工学研究院, 助教授 (30274484)
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| Co-Investigator(Kenkyū-buntansha) |
FURUKAWA Akinori Kyushu University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (30112410)
MATSUSHITA Daisuke Kyushu University, Faculty of Engineering, Assistant Professor, 大学院・工学研究院, 助手 (60284535)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥13,300,000 (Direct Cost: ¥13,300,000)
Fiscal Year 2004: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 2003: ¥7,900,000 (Direct Cost: ¥7,900,000)
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| Keywords | Multi-phase flow / Bubble / Bubble chain / Bubble interaction / Bubble generation / Flow visualization |
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| Research Abstract |
It was confirmed that a characteristic flow field existed in surroundings of the rising bubble chain which was row though it was generated from a single nozzle. The bubble chain was generated in the water pool with both the bubble diameter and bubble generation frequency accurately controlled, and the generation process of this characteristic flow field in the neighborhood of the bubble chain was observed. The lift force acting on bubbles in the bubble chain is larger than the one acting on a single bubble, due to the flow field formed by the leading bubbles. It is considered that the wake of the leading bubbles caused the instability of the trailing bubbles, especially the deformation of bubble shape, which resulted in the bent of the bubble chain.
The characteristic flow field in the neighborhood of the bubble chain was visualized by PIV (Particle Image Velocimetry) method. The mathematical model of the generation of the liquid jet was also constructed by using the momentum theorem. T
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he control volume was introduced in the liquid field in the neighborhood of the bubble chain and it was shown that there exists the characteristic force acting on the bubble chain due to the liquid jet formation. The validity of the model was evaluated by comparing with the experimental results.
The hydrodynamic interaction between a pair of bubbles rising in stagnant liquid was studied both experimentally and numerically. It was understood that the bubble Reynolds number plays the dominant role in the equilibrium distance between a pair of rising bubbles in vertical line. It was also confirmed experimentally that there exists the equilibrium distance. Moreover, it was confirmed numerically that the equilibrium distance decreased and lead to the contact of a pair of bubbles with the decrease in the Reynolds number.
The bubble behavior under the interaction was observed with the microscope camera. The Fourier descriptor was used for the obtained image and the bubble shape was quantified. The correlation between the bubble shape and the bubble behavior were considered with a highly accurate evaluation of the bubble center of gravity position. A large deformation of bubble shape was observed when a pair of bubbles collided and it was confirmed that the bubble rising velocity changed greatly.
Both the hydrodynamic interaction and the coalescence between a pair of rising bubbles were considered experimentally and numerically. It was clarified that Reynolds number plays the significant role the generation of a steady bubble chain. It was also confirmed that both the Weber and Reynolds numbers are significant parameters, especially the physical property of viscosity is important, both for the prevention of the coalescence of bubbles and for the steady operation of bubble chain induced pump. Less
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