1993 Fiscal Year Final Research Report Summary
A study on rollover of two density-stratified layrs of liquids
| Project/Area Number |
04452145
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thermal engineering
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
TANASAWA Ichiro IIS, UNIVERSITY OF TOKYO PROFESSOR, 生産技術研究所, 教授 (30013105)
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| Co-Investigator(Kenkyū-buntansha) |
MUNAKATA Tetsuo MECHANICAL ENGINEERING LABORATORY, AIST SENIOR RESEARCHER, 機械技術研究所, 主任研究官
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| Project Period (FY) |
1992 – 1993
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| Keywords | Rollover / Buoyancy convection / Density-stratified liquid layr / Natural convection / Heat and mass transfer / Flow visualization / Numerical simulation / Shadowgraph technique |
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| Research Abstract |
The rollover referred to in this report is a rapid mixing of two layrs of liquids which initially were stratified stably in a vessel due to a density difference. Heat invasion through the vessel wall into the liquid layrs induces buoyancy convection in both of the liquid layrs. Subsequent heat and mass transfer inside each of the liquid layrs and between the two layrs, and evaporation at the free upper surface gradually reduces the density difference between the two liquids. Finally the stability of the two layrs is lost, leading to a rapid mixing of the both liquids.
The sequential processes from the start of buoyancy convection to the onset of rollover were studied experimentally and numerically. In the experiment, the profile and movement of the interface between the two liquid layrs and the flow patterns were visualized with the shadowgraph technique. The timewise changes in the distributions of temperature and density were measured at the same time. The distribution of flow velocity near the vertical wall of the vessel was obtained by measuring the displacement of tracer particles illuminated with a laser light. The results of experiment elucidated the process leading to the complete mixing of the two liquids. When the density difference became small, the boundary layr flow in the lower liquid rising along the wall penetrated deep into the upper layr and finally reached the free surface. From this moment on the rapid mixing of the entire fluid took place. The boundary between the two liquids descended as the mixing proceeded, became fuzzy, and vanished in the end.
Numerical simulation using a large-scale computer has shown quite the same results.
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Research Products
(8 results)
