| Project/Area Number |
11650193
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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 | Toyota Technological Institute |
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Principal Investigator |
TANAKA Shuji Toyota Technological Institute, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (40029327)
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| Co-Investigator(Kenkyū-buntansha) |
URITA Akira Toyota Technological Institute, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (40288551)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Separated Flow / Turbulent Wake / Three-Dimensional Flow / Organized Structure / Finite Circular Cylinder / Circular Disc Aerofoil / Shedding Vortices / 組織構造 / 鈍頭物体 / はく離 / 位相平均法 / 乱流後硫 / 渦構造 |
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| Research Abstract |
The unsteady three dimensional flow structures behind a finite circular cylinder with an aspect ratio of 10 and a thin circular disc at various angles of attack have been investigated. The flow details in the frequency domain were determined using FFT analyzer and the features of large-scaled organized structures in the turbulent wakes were obtained with phase-locked averaging technique in the time domain. Three typical organized structures with different frequencies and different features were extracted from the complex turbulent wake flows. The results can be summarized as follows :
1. The wake flows behind a finite circular cylinder typically consist of the following three large-scaled organized vortex structures with different origins, (1) low frequency component(tip component), which is a pair of longitudinal vortices shed from a tip of the cylinder, (2) mid-frequency component (mid-span component), which is hairpin typed organized vortices shed from a mid-span of the cylinder, (3)
… More
high frequency component (root component), which is shed from the root of the sylinder and quite similar to the two-dimensional Karman's vortices .
2. The wake flow behind a finite circular cylinder consists of not only the typical three types of organized vortex structures described above but also various types of vortices with intermediate features and frequencies as well as small eddies with almost random configurations. Therefore, the turbulent wake behind a circular cylinder appears to be a very complicated flow at a glance.
3. The wake flow behind a thin circular disc with longituninal vortices, which is a typical vortex features for unstalled conditions, indicates only a few organized structure. The wake flow with ring-type vortices, which is typical vortex features for stalled conditions, indicates a clear organized flow structures with well defined frequency. The Strouhal numbers of the frequency based on the height of the shed ring-type vortices are in the range from 0.19 to 0.22. Less
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