| Project/Area Number |
17560430
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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 |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | University of Miyazaki |
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Principal Investigator |
OZONO Shigehira University of Miyazaki, Applied Physics, Professor (10169302)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAGI H. Univ. of Miyazaki, Applied Physics, Research Associate (90219741)
KIKUGAWA H. Oita National College of Technology, Mechanical Engineering, Associate Prof. (70321528)
CAO Shuyang Tokyo Polytechnic University, Structural Engineering, Associate Prof. (00334532)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,050,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Multi-fan / Active turbulence generation / High-Reynolds number turbulence / Turbulence intensity / Turbulence scale / 乱れのスケール / 慣性小領域 / ロックイン |
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| Research Abstract |
The purpose of the present research is to generate both high-intensity and large-scale turbulence by using a multi-fan wind tunnel. Since air flow is driven by an array of small 99 fans, various flows can be generated., However, the question as to how to generate both high-intensity and large-scale turbulence is still open. As basic driving methods, we have (1) uniformly active mode and (2) quasi-grid mode, but the resulting turbulence is far from the real atmospheric turbulence.
By combining driving mode (1) and (2), we have tried an active-grid method. With a few sinusoidal fluctuations fed, we have measured turbulent fields with attention focused on whether turbulence intensity can be amplified. That means we try to generate high-Reynolds number turbulence to amplify turbulent energy by providing external fluctuations. Except a sharp peak associated with input fluctuations, there is little change in the resulting spectra.
After an update of the wind tunnel used, suction becomes available by rotating fans in the reverse direction. It was found that the effect of suction is to maximize mixing immediately downstream of blowing, and random differences in phase of each fan allow mixing to enhance. However, we have not removed pulsating component originated from the external fluctuations yet.
Furthermore, we have attempted fractal arrangement of the fans. The resulting turbulence satisfied isotropy to some degree, but non-uniformity survives over some streamwise distance.
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