Study on formula for predicting convective heat transfer coefficient in urban canopy layer taken account of atmospheric stability
| Project/Area Number |
16560529
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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 |
Architectural environment/equipment
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| Research Institution | TOKYO POLYTECHNIC UNIVERSITY |
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Principal Investigator |
OHBA Masaaki Tokyo Polytechnic University, Faculty of Engineering, Professor, 工学部, 教授 (90130947)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Nobuyuki Tokyo Polytechnic University, Faculty of Engineering, President, 学長 (70097301)
KURITA Tsuyosi Wind Engineering Center Co., Ltd, Researcher, 技術部・研究員
OHGURO Masayuki Taisei Construction Ltd., Researcher, 建築技術研究所, 主任研究員
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Convective heat transfer coefficient / Thermally stratified wind tunnel / Urban canopy laver / Atmospheric stability / Bulk Richardson number / 対流熱伝達率 |
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| Research Abstract |
The present study attempted to elucidate the formula for predicting convective heat transfer coefficient in urban canopy layer by using a thermally stratified wind tunnel. The following results were obtained by the reserach for two years.
1.Characteristics of kinematics and heat flux in unstable flow
The wind velocity and temperature in unstable layer were measured by using hot-wire and cold-wire simultaneously. The turbulence intensity on U and W component was found to be higher when bulk Richardson number indicated unstable. The horizontal momentum fluxes were kept constant regardless of bulk Richardson numbers. Vertical heat fluxes had maximum values at a height of 1/5 to 1/4 of thermal boundary layer thickness regardless of bulk Richardson numbers.
2.Thermal characteristics in the wake near behind two-dimensional fence
Compared to the case without 2-D fence, the temperature behind the fence increased and vertical heat fluxes indicated negative value at a height of fence.
3.Experimental formula for predicting convective heat transfer coefficients in urban canopy layer
The bulk Richardson number of approaching flow was varied in a range of 0 to -0.26 according to the change of wind velocity in a condition that the floor panel of thermal stratified wind tunnel was kept constant. As a result, the convective heat transfer coefficient was higher when the instability of airflow increased. The experimental formula was achieved expressing the convective heat transfer coefficient as a function of bulk Richardson number and wind velocity. The convective heat transfer coefficient increased when bulk Richardson number indicated unstable. In order to compare with the formula of the convective heat transfer coefficients proposed by other researchers, experimental data must be accumulated for obtaining a high-precision experimental regression formula.
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Report
(3 results)
Research Products
(14 results)
