1998 Fiscal Year Final Research Report Summary
Boiling Bubble Dynamics by Numerical Simulation
| Project/Area Number |
09650245
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TAKATA Yasuyuki Kyushu University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (70171444)
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| Co-Investigator(Kenkyū-buntansha) |
KUBOTA Hiromi Kyushu University, Faculty of Engineering, Research Associate, 工学部, 助手 (10117103)
ITO Takehiro Kyushu University, Faculty of Engineering, Professor, 工学部, 教授 (20037740)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Volume of Fluid (VOF) / Surface tension / Phase change / Nucleate boiling / Bubble |
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| Research Abstract |
The present study is to develop a numerical method based on VOF(Volume of Fluid) for thermal and fluid flow with liquid-vapor phase change and to apply its method to the bubble dynamics of boiling phenomena. We developed an improved donor-acceptor method that can trace liquid-vapor interface with higher accuracy and new algorithm for liquid-vapor phase change including volume change between two phases.
In the first year, we performed simulation of a helium bubble initially placed on a flat surface and heated under atmospheric pressure. Computation domain is 100mum and 200mum in radial and vertical directions, respectively, using axsymmetric two-dimensional coordinate. Initial bubble of 20mum in diameter is placed on the surface with contact angle of 50 and heated with 0.2K in degree of superheating. The departure diameter calculated is about 55mum and this value is comparable with the values (60-80mum) usually observed in experiments. We obtained velocity vectors, pressure and temperature distributions during the bubble growth and departure. The thermal boundary layer calculated is quite similar to those obtained by schlieren photograph.
In the second year, we tried to simulate a bubble from a cavity. The cavity size is 20IOTAm and 20IOTAm in diameter and depth, respectively. Inside the cavity, initial bubble is placed and heated with 0.2K in degree of superheating. The initial bubble grew over the cavity and was finally lifted up by buoyancy. After the departure of bubble there remained small bubble inside the cavity and it should be a nuclei of next bubble. Unfortunately, some instabilities appeared and we could not continue further calculations. However, the distributions of temperature and local heat transfer coefficients are quite similar to those usually observed in experiments.
The numerical method developed in the present study is applicable also to solid-liquid phase change problems.
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Research Products
(12 results)
