| Project/Area Number |
17560156
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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 |
Fluid engineering
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| Research Institution | Oita University |
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Principal Investigator |
HAMAKAWA Hiromitsu Oita University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30243893)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | fluid dynamics / exhaust heat recovery / drag reduction / Karman vortex / fin |
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| Research Abstract |
Drag reduction and turbulent characteristics of the rough surface with the fins were experimentally investigated to improve the performance of heat exchanger tube. We measured the distributions of the mean velocity, the intensity of velocity fluctuation, the spectrum of velocity fluctuation and the coherence distribution around the fin tubes by using hot wire, and conducted flow visualization by smoke wire method. As a result following conclusions were obtained.
1. The solid fir which mounted roughly on the surface of heat exchanger tube worked as not only the increase of heat transfer area but also the guide vane.
2. When the fin pitch was small, the angle between the main flow and the fin was small, and the inclination of the flow on the surface of a tube was small. The flow on the surface of the tube was inclined by the fin.
3. When the serrated fin pitch was large, the drag increased compared with the solid fin tube because the flow separated from the edge of sertated fin. And the heat transfer performance decreased because the surface of the fin did not contact easily with the main flow.
4. The flow was inclined greatly by the edge of serrated fin when the pitches of serrated fin become small. The cause of the heat transfer enhancement was not only the increase of turbulence by the fin but also the increase of the contact distance between the main flow and the surface of the tube or the fin. The drag increased compared with the solid fin tube because the inclination of the flow was large at the serrated fin tube.
5. When the serrated fin pitch become small further, the fluid did not flow inside of the clearance between the fins. Therefore fluid flowed chiefly outside of the fin parts, the heat transfer performance did not increase.
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