| Project/Area Number |
11450076
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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 |
Fluid engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
KIKUYAMA Koji Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (90023192)
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| Co-Investigator(Kenkyū-buntansha) |
ASAKURA Eiji Nagoya University, Graduate School of Engineering, Research Associate, 工学研究科, 助手 (90135327)
HASEGAWA Yutaka Nagoya University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (20198732)
NAGAFUJI Tomotatsu Nagoya University, School of Engineering, Professor, 工学部, 教授 (30303655)
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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 |
¥12,700,000 (Direct Cost: ¥12,700,000)
Fiscal Year 2000: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1999: ¥10,400,000 (Direct Cost: ¥10,400,000)
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| Keywords | Boundary Layer / Transition / Coriolis Force / Centrifugal Force / Wall Curvature / Velocity Distribution / Goertler Vortex / Tollmien-Schlichting Waves |
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| Research Abstract |
The boundary layer flows in rotating channels such as impeller passages of turbomachinery are dominated by the centrifugal and Coriolis forces due to the wall curvature and system rotation, respectively, which predominate the boundary layer development by suppressing or promoting the turbulent motion. Though many studies have been made about the turbulent boundary layer over a concave or convex surface in the stationary state, the resultant effects due to the Coriolis force in the rotation frame have scarecely been made.
In the present project, the velocity and turbulent intensity are measured near the concave surface in channels whose centerline radii of curvature are 1,000mm and 2,000mm, respectively, for different rotating conditions.
Main results can be summarized as follows ;
(1) The Coriolis force exerting normally toward the wall promotes the Goertler instability and advances the transition of the flow from laminar to turbulent state, but that exerting from the wall delays the transition.
(2) The transition occurrs when the Reynolds number based on the momentum thickness exceeds a critical value, regardless of the difference in the rotation rate and the main flow velocity.
(3) At negative rotation rates the fluctuating component is suppressed and a further decrease generates a different type of instability.
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