Study on unsteady separated flow and evaluation of aerodynamic admittance function
| Project/Area Number |
13450186
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
構造工学・地震工学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SHIRATO Hiromichi Kyoto University, Department of Global Environment Engineering, Associate Professor, 工学研究科, 助教授 (70150323)
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| Co-Investigator(Kenkyū-buntansha) |
YAGI Tomomi Kyoto University, Department of Global Environment Engineering, Research Associate, 工学研究科, 助手 (30293905)
MATSUMOTO Masaru Kyoto University, Department of Global Environment Engineering, Professor, 工学研究科, 教授 (00026270)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥15,100,000)
Fiscal Year 2002: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2001: ¥12,300,000 (Direct Cost: ¥12,300,000)
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| Keywords | Buffeting / Separated shear layer / Spatial correlation / Bluff body / Surface pressure / Fluctuating wind velocity / Simultaneous measurement / コヒーレンス / 多点同時圧力計測 / 変動気流 / 空力アドミッタンス / Sears関数 / 渦 |
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| Research Abstract |
Gust response analysis of structures due to natural wind turbulence has an assumption on the equivalence of span-wise coherence of oncoming wind velocity fluctuation and that of aerodynamic forces on each section. Wind tunnel experiments reveals, on the other hand, that the aerodynamic forces or surface pressure appear more correlated properties. In this research project, to clarify the mechanism of the increase of coherence, surface pressures as well as wind velocity for the 2-D rectangular models of slenderness ratio B/D=1 (square) and 5 were measured. Pressure measurement system at multiple points and the 3-D periodic flow generator were newly installed. The 3-D periodic flow generator can control the frequency of sinusoidal flow in the mid part and the both side parts along model span independently.
The following points were newly found:
1) Separating flow plays most important role on the increase of spanwise correlation, in case of B/D=5. Separating flow reattaches on the side surfa
… More
ce to form the separation bubble. The bubble forms more two-dimensionally even in the 3-D periodic flow. Temporal and spatial distribution of the surface pressure demonstrates the sudden expansion of pressure maxima towards spanwise direction, which may increase the coherence.
2) As for the square cross section (B/D=1), the increase of spanwise pressure correlation was again recognized but not so significantly as B/D=5. Separating flow cannot reattach on the side surface. Which interferes the formation of closed space similar to the separation bubble in B/D=5. The important factor for the increase of spanwise correlation may be the generation of separating flow itself.
3) Spatial pattern of the sinusoidal flow during its passage through 2-D flat plate (B/D=30) was also investigated in wind tunnel. The pattern is assumed to be sustained maintained in the unsteady thin airfoil theory, which leads to the well-known Sears function. In order to capture the extent of distortion in the sinusoidal fluctuation of oncoming vertical wind velocity and surface pressure, phase averaging technique was applied to the measured row data. It was found that the surface pressure and the vertical wind velocity signal deviate significantly from sinusoidal wave. However, the pressure difference between upper and lower pressure indicated almost sinusoidal wave. Therefore, it was confirmed that the assumption is hold, consequently. Less
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Report
(3 results)
Research Products
(6 results)
