1992 Fiscal Year Final Research Report Summary
Abnormally large acceleration of bubbles in flows of bubbly liquid
| Project/Area Number |
03805007
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
ISHII Ryuji Kyoto Univ.,Faculty of Eng.,Assoc. Prof., 工学部, 助教授 (20026339)
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| Co-Investigator(Kenkyū-buntansha) |
UMEDA Yoshikuni Kyoto Univ.,Faculty of Eng.,Instr., 工学部, 助手 (30026132)
HATTA Natsuo Kyoto Univ.,Faculty of Eng.,Prof., 工学部, 教授 (30026041)
MORIOKA Shigeki Kyoto Univ.,Faculty of Eng.,Prof., 工学部, 教授 (60029395)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Multi-Phase Flow / Bubble-clouds / Nozzle Flow / Instability / Voidage Wave |
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| Research Abstract |
1. A numerical sckeme was developed for flow around a deformable bubble rising through an incompressible viscous fluid. The solution algorithm is a modified MAC method. The bubble shape and the drag coefficient were determined for various Reynolds and the Weber numbers.
2. Characteristics of bubbly flows were investigated theoretically and experimentally. First a new model equation of motion governing a dispersed bubble phase was proposed. Next, herperbolicity of the resultant system of governing equations for the bubbly flow was investigated in detail. Numerical simulations of bubbly flows through a converging- diverging nozzle were carried out on a supercomputer Fujitsu VP-2600 by using the propsed system of model equations. The numerical results were compared with the experiments in a water-nitrogen blow-down facility. It was confirmed that the numerical results agrees well with the experiments.
3. Flow visualization by instantaneous photographs with a stroboscopic flash was performed to investigate the flow behavor of bubble clouds. A few interesting phenomena were observed in the downstream region of the nozzle throat. One of them, for example, is an "expansion-shock" of the bubble phase. This phenomenon cannot be explained theoretically at least for the present.
4. The effects of impurity or surfactant on the flow behavior of bubbles remained for future study.
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