| Project/Area Number |
08650211
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
KOSO Toru Kyushu University, Institute of Advanced Material Study, Associtate Professor, 機能物質科学研究所, 助教授 (40150528)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1997: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Turbulent Jet / Vortex Structure / Flow Visualization / Thee-Dimensional Re-construction / Hot-Film Velocimeter / Laser-Induced Fluorescence |
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| Research Abstract |
The structure and dynamics of vortices in a fully developed region of a coflowing circular jet is investigated in a water tunnel experiment. The cross sections of the jet are visualized by laser-induced fluorescence and a digital image processing is applied to the sectional images to reconstruct a three-dimensional pictures of vortex structures. The fluorescence dye is premixed to a jet fluid which Reynolds number is 1700, and a cross section normal to jet axis is illuminated by a thin laser sheet. Three-dimensional pictures are reconstructed by image stacking of cross sectional images using a fast and memory saving computer program developed by us.
Three-dimensional pictures of vortices indicate that the structure of jet is characterized by fully three-dimensional large-scale vortices. The whole region of the fully developed jet is found to be filled with numerous streamwise vortices. And some of them are found to form U-shape bend vortices of which top is inclined to backward and outward.
To investigate the velocity field in the visualized structure, the hot-film measurement and flow visualization are carried out simultaneously. The signals from a X hot-film probe are sampled synchronously with the recording of cross sectional images. This simultaneous measurement gives the information of velocity field induced by the visualized vortex structure. Attention is focused on isolated structures in far edge region of jet. the results indicate that the structures are characterized by three-dimensional vortex tubewhich circulation is large and core diameter is order of nozzle diameter.
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