| Project/Area Number |
09650176
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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 | IWATE UNIVERSITY |
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Principal Investigator |
FUNANAKI Ken-ichi Iwate University Department of Mechanical Engineering Professor, 工学部, 教授 (00219081)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | SEPARATION / CASCADE / WAKE / BOUNDARY LAYER / CONTROL / 境界層 / 剥離泡 / 翼 / 乱流 |
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| Research Abstract |
Behavior of the separation bubble on the suction surface of a compressor or a turbine blade has been attracting attention of researchers and designers of turbomachines for several decades because the separation is closely related to efficiency, stability, heat transfer and noise generation encountered in turbomachines. A number of attempts have been made to control separation and/or separation bubble on an isolated airfoil using conventional devices such as vortex generators or other devices like acoustic excitation. However, few of these devices were ever applied to turbomachines because they were far from practical in turbomachines or were accompanied with severe penalties in service. In consideration of the flow field inside of the turbomachines, one of the most realistic approaches to control the separation is to utilize various sources of intense turbulence inherent in the turbomachines, such as stationary or unsteady wakes coming from upstream blade rows. Recently much concern ha
… More
s arisen about a technique for improving stage efficiency that changes the interaction between upstream stator wakes and the downstream stator vanes of concern by shifting the upstream stator vanes in the circumferential direction. This technique is frequently called 'airfoil clocking' or 'airfoil indexing', and several researchers have examined to what extent the technique could improve the stage efficiency. It was found that some configurations could maximize the stage efficiency, although the mechanism of the clocking was not fully understood yet. A similar approach with the airfoil clocking technique seems to be applicable and practical in controlling the separation and/or separation bubble encountered in turbomachines because it does not require any extra devices for the purpose.
This study shows an attempt using the wake from a stationary bar to minimize aerodynamic loss associated with a separated boundary layer on a large-scaled blunt airfoil that is a model of the leading edge portion of actual airfoils. In this study the bar is transversely shifted (or 'clocked') so that the bar wake interacts with the boundary layer on the test model in different manners. Detailed measurements by use of a hot-wire probe reveal that it is possible to reduce the boundary layer loss by positioning the wake-generating bar at a proper location. Less
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