Structure of Turbulent Heat Transfer in a Separated and Reattached Flow
| Project/Area Number |
04650170
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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 | Tohoku University |
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Principal Investigator |
OTA Terukazu Tohoku Univ., Faculty Eng., Professor, 工学部, 教授 (00006678)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKAWA Hiroyuki Tohoku Univ., Faculty Eng., Res. Assoc., 工学部, 助手 (40221668)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Convective Heat Transfer / Turbulent Flow / Separated Flow / Reattached Flow / Boundary Layr / Heat Exchanger |
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| Research Abstract |
The purpose of the present study was to investigate the turbulent heat transfer mechanism in the separated, reattached, and redeveloped regions of two-dimensional air flow over a blunt flat plate with finite thickness. Measurements of heat transfer and flow were conducted using the same plate in order to clarified exactly the correlation between the heat transfer behaviors and the flow ones. The main points obtained are summarized as follows.
The maximum heat transfer coefficient locates at 8.2H( H being half plate thickness ) and the mean reattached point is 9.6H, which was determined as a point of 50% reverse flow rate. That is, the maximum heat transfer point exists somewhat downstream of the flow reattachment. At the point of maximum heat transfer coefficient, the reverse flow rate is only 15% and the temperature fluctuating intensity and the Reynolds stress near the wall are relatively higher compared to those at the reattachment point.
In the separation bubble, the location of the
… More
maximum temperature fluctuations in different from that of maximum velocity fluctuation and is situated in the outer region of the separated shear layr.
The integral time scale of the temperature fluctuation attains maximum near the dividing boundary in the separation bubble and minimum near the point of the maximum temperature fluctuation intensity. On the other hand, it does not show essential change in the whole region of the redeveloped flow.
The characteristics of the power spectra and probability density function depend strongly upon the flow feature, such as separated, reattached, and redeveloped flow regions. In the reattached flow region, there exists a broad hump of the power spectrum due to the shedding of large-scale eddies from the separation bubble. Furthermore, based on the results of the skewness and the flatness factors, the effect of the separation and reattachment of the flow upon the statistical features of the temperature fluctuation extends far downstream.
The correlation between the temperature fluctuation near the reattachment flow region and the velocity fluctuation of the low frequency flapping motion is found to be very weak and two components of the turbulent heat flux were measured using a triple wire probe. Less
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Report
(3 results)
Research Products
(21 results)
