2002 Fiscal Year Final Research Report Summary
MECHANISM OF HEAT REMOVAL BY HEAT TRANSPORT VORTEX
| Project/Area Number |
12650196
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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 | University of Yamanashi |
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Principal Investigator |
ICHIMIYA Koichi UNIVERSITY OF YAMANASHI, FACULTY OF ENGINEERING, PROFESSOR, 工学部, 教授 (30037923)
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| Co-Investigator(Kenkyū-buntansha) |
TORIYAMA Koji UNIVERSITY OF YAMANASHI, FACULTY OF ENGINEERING, RESEARCH ASSISTANT, 工学部, 助手 (50313789)
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| Project Period (FY) |
2000 – 2002
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| Keywords | THERMAL ENGINEERING / IMPINGING JET / MIXED CONVECTION / FIXED VORTEX / RENEWAL VORTEX / NON-UNIFORM VORTEX / OSCILLATION / HEAT TRANSFER |
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| Research Abstract |
In the present case, heat transport vortexes are composed of the renewal vortex by impinging jet and fixed vortex by the mixed convection. We studied on how vortex transports heat and contributes to heat transfer enhancement by examining the characteristics of the impingement heat transfer and the mixed convection.
In the first stage, the heat transfer characteristics on impinging jet were studied on a single circular jet and in transient process. Experiment was performed using thermosensitive liquid crystal and (r,g,b) method. Effects of the shape and the attitude of the nozzle were investigated on the local heat transfer. Experiments on impinging jet were expanded to four circular nozzles arranged in square-type. The two-dimensional behavior of the local Nusselt number was corresponded to the flow visualization by oil film method on the impingement surface. The average Nusselt number was expressed by the geometric function and Re^<2/3>. Impingement heat transfer by annular nozzle was also captured in two-dimensional map. Experimental formulas of the local Nusselt number were obtained in power-law expressions of r/r_p (r_p : position of local Nusselt number)for the major and minor flow regions.
In the second stage, the heat transfer and flow characteristics of mixed convection in a horizontal square duct with three heat transfer walls were examined numerically and experimentally. The flow behavior depends on the relative temperature difference between wall and inlet fluid. The fluid near the wall flows backward to compensate the buoyancy induced flow. The size of the flow reversal increases with increase of Richardson number. In side wall heating and cooling, a swirl flow is generated longitudinally and at the cross section, several vortexes can be found. These flow behavior transports heat and affects the local heat transfer on the walls.
The final report is composed of two chapters on impinging jet and mixed convection.
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