2001 Fiscal Year Final Research Report Summary
A Turbulent Flow Control in a Curved Pipe due to Swirling Flows
| Project/Area Number |
10650190
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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 | Okayama University of science |
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Principal Investigator |
TAKAMI Toshihiro Faculty of Engineering, Professor, 工学部, 教授 (40144886)
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| Co-Investigator(Kenkyū-buntansha) |
ANAKI Keisuke Faculty of Engineering, Lecturer, 工学部, 講師 (90299181)
MARUYAMA Yuichi Faculty of Engineering, Assistant Professor, 工学部, 助教授 (20229628)
YANASE Shinichiro Okayama University, Engineering, Professor, 工学部, 教授 (20135958)
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| Project Period (FY) |
1998 – 2001
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| Keywords | Turbulent Flow / Pipe Flow / Secondary Flow / Swirling Flow / Curredn Pipe / Drug Reduction |
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| Research Abstract |
A control of turbulent flow through a curved pipe is experimentally investigated using swirling flows. (1) In 1998, in case of weaker swirls injected, a flow friction coefficient of the turbulent curved pipe was found to reduce compared with that of the non-swirling case. (2) In 1999, in a such case of drag reduction, detailed measurements of the velocity distribution revealed that an interesting swingback phenomenon of flow patterns appeared in the vortical flow structure of the developing curved pipe flow. (3) In 2000, in order to understand relations between the flow friction and the flow pattern in the turbulent curved pipe flow, direct measurement methods of the wall shear stress were studied using both a wall film sensor (WFS) and a micro flow sensor (MFS). (4) In 2001, in a strong swirling flow through the curved pipe, developing flow patterns were measured to study relations between flow frictions, swirl intensities and the vortex-core orbit.
The above-mentioned result during 4 years is summarized as follows. The vortex pair of the secondary flow is induced in the turbulent curved pipe flow due to the centrifugal force, to increase the flow friction. When the weak swirling flow/swith the vortex intensity of secondary flow is injected into the curved pipe, the drag reduction occurs according to the decrease of the wall shear stress which is caused by the primary flow unified by the swingback phenomenon in the developing curved pipe flow. On the other hand, when the strong swirling flow is injected, the drag promotion is observed because the primary flow remains to shift inwards and the swirling vortex is not so declined. These phenomenological results indicate that the control of the curved pipe flow using swirling flows is applicable.
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