1997 Fiscal Year Final Research Report Summary
Study on Two-Phase Hydrodynamic Structure of Bubble Layers under Forced Convective Subcooled Flow Boiling
| Project/Area Number |
08458124
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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 |
エネルギー学一般・原子力学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SERIZAWA Akimi Kyoto Univ.Dept.of Nucl.Eng., Professor, 工学研究科, 教授 (10027146)
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| Co-Investigator(Kenkyū-buntansha) |
KAWARA Zensaku Kyoto Univ.Dept.of Nucl.Eng., Instructor, 工学研究科, 助手 (10201451)
TAKAHASHI Osamu Kyoto Univ.Dept.of Nucl.Eng., Instructor, 工学研究科, 助手 (40127098)
KATAOKA Isao Kyoto Univ.Dept.of Nucl.Eng., Assoc.Prof., 工学研究科, 助教授 (80093219)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Subcooled boiling / Bubble layers / Two-phase flow structure / Critical heat flux / Film flow / Experiment / Numerical simulation / Physical models |
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| Research Abstract |
The initial research plan has been extended to cover, not only multi-fluid hydrodynamic structure of bubble layers, but also wider aspects of forced convection subcooled flow boiling and critical heat flux both experimentally and analytically. This includes (1) bubble behaviors under conditions up to the DNB point, (2) phase distribution and turbulence mechanisms in various channels, (3) 2-dimensional time-dependent film flow behavior, (4) turbulent dispersion of liquid droplets in turbulent shear flow field, awl (5) prediction of the DNB and film dryout.
Experimental observations have revealed several different mechanisms dominating bubble lateral migrations, resulting in non-uniform distributions of phases and turbulence. These general trends were successfully predicted by numerical simulations. We also developed an analytical model to numerically predict critical heat fluxes (DNB and dryout heat flux) based on multi-fluid models. In order for these models to incorporate more accurately the effects of time-dependent spatially varying film thickness and liquid droplets behavior in turbulent gas flow, we have developed a new ultrasonic echo technique with high spatial and time resolutions and a numerical simulation model to calculate deposition and turbulent diffusion of liquid droplets based on two-way coupling method. The latter method has been shown to be a good tool to objectively evaluate the validity of existing correlations.
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