1986 Fiscal Year Final Research Report Summary
Effect of Eddy Formation on Transient Phenomena of Free Convection in an Enclosure
| Project/Area Number |
60550157
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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 |
Thermal engineering
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| Research Institution | OITA UNIVERSITY |
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Principal Investigator |
YOSHIOKA Keisuke Dept. of Mech. Engng. Fac. of Engng. Oita Univ., 工学部, 教授 (40037792)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Free Convection / Vertical Enclosure / Transient State / Eddy Formation / 流れの可視化 |
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| Research Abstract |
Effects of eddy formation on heat transfer were studied by making account of cooling condition. Becouse of transpiration fluid as air, emissivity of aluminum surface was measured. The emissivity was determined as a value of 0.44. Employed vertical enclosure was that the height = 1 m, the width = 0.5 m and the distance of two walls = 0.05-0.25 m.
Vortex motions are observed by a smoke method. The motion is detected on each side of conducting wall. On the hot wall, the frequency is ranging from 1.2 to 2.1 Hz and wave length is almost 70 mm. A concluding remark is given by analyzing boundary layer equation that a pressure deviation at the outer leading edge of boundary layer gives rise a time elapsing to developed flow.
Small undulatory motion, on the other hand, is observed in the boundary layer. On the hot wall, the frequency is ranging from 4 to 6 Hz and the wave length is 30-40 mm with the amplitude of 5-15 mm. This weak turbulence gives a time elapsing to developed flow and some thickening of the boundary layer.
As a result of flow simulation on a computer, in a case of air flow, it is suggested that the distance of two walls should be chosen as the suitable characteristic length.
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