1989 Fiscal Year Final Research Report Summary
Systematic Research on the Characteristics of Impingement Heat Transfer in Comparatively Narrow Space
| Project/Area Number |
62550147
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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 | University of Yamanashi |
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Principal Investigator |
ICHIMIYA Koichi Yamanashi University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30037923)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAZAWA Toshiyoshi Yamanashi University, Faculty of Engineering, Research Associate, 工学部, 助手 (90020396)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Thermal Engineering / Forced Convection / Impingement Heat Transfer / Laminar Jet / Turbulent Jet |
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| Research Abstract |
The impingement flow has been increasingly utilized for enhancing the intensity of heat and mass transfer of heat transfer media. Conditions corresponding to such flows are encountered in engineering device to remove the heat from the electric device, to dry the film or the paper and to flatten the temperature distribution of high temperature steel slab. So, we should study on the beat transfer of impinging flow in the narrow space between the nozzle and the impinged surface.
In the present study, we experimented and analyzed by changing the kind of the nozzle ( slit-type nozzle and the circular nozzle ), the number of the nozzles ( a single nozzle and array of the nozzles ), the distance between the nozzle and the impinged surface, the size of the impinged surface, the flow rate and the pitch of the nozzles. Additionally, numerical analysis was performed in the laminar impinging jet flow.
In the first step, the effect of the size effect of a heated slab was examined numerically on the c
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haracteristics of flow situation and impingement heat transfer caused by a laminar jet. It was found that the generation of recirculating flows near the side surface of a heated slab and the upper confined plate depends on the ratio of the size of a heated slab and the nozzle width (W>l, W<1) and the spanwise variation of the local Nusselt number on the lower wall exhibits one or two maxima. In the second step, experiments were performed on the characteristics of impingement heat transfer by three slot jets. For laminar jet, experimental values were compared with numerical results. For turbulent jet, two peaks of the local Nusselt number were obtained behind the second nozzle. The position of the second peak approached the nozzle with the decrease of the space between nozzle and impinged surface. The average Nusselt number between the central and the second nozzle was determined by the ratio was determined by the ratio P/H and tile Reynolds number based on the pitch of the nozzles. In the third step, the impingement heat transfer caused by a single circular jet and four-turbulent circular jets. For a single circular jet, two peaks of the local Nusselt number were produced at R=0.5 and the position depended on Reynolds number. For four circular jets, the maximum value of mean Nusselt number was obtained at the dimensionless nozzle-impinged surface spacing H=1.5-2.
These results will be applied in the practical facility as the basic data. Less
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Research Products
(6 results)
