1997 Fiscal Year Final Research Report Summary
Active Control and Detection of Presage of Separation for Reduction of Aerodynamic Noise
| Project/Area Number |
08455085
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
MOCHIZUKI Osamu Hokkaido Univ., Grad.School of Mech.Eng., Associate Prof., 大学院・工学研究科, 助教授 (50157830)
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| Co-Investigator(Kenkyū-buntansha) |
KIYA Masaru Hokkaido Univ., Grad.School of Mech.Eng., Prof., 大学院・工学研究科, 教授 (50001160)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Aerodynamic Noise / Active Control / Separation / Wake / Unsteady Flow / Vortex Interaction / Vortical Structures / Vortex Rings |
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| Research Abstract |
A final goal of this study is to reduce aerodynamic noises by investigating separation. Turbulent vortical structures of 3-dimentional wake, an open-loop type control of separation in a two-dimensional diffuser, and vortex rings as a transmitter of momentum to the separation region are studied experimentally. Main results of this study are summarized as follows,
(1) An incoming turbulent wake of a moving rod in a plane perpendicular to a main flow improves a pressure recovery coefficient of the two-dimensional diffuser with and without separation. This is a new finding in this field.
(2) Effects of a quasi-steady incoming wake of the rod on performance in the diffuser are investigated. The rod is installed upstream of the inlet of the diffuser. Time-mean velocity distributions and turbulent intensity distributions are presented for several combinations of the diameter and position of the rod. It is found that there exists an optimum combination for the improvement and reduction of loss. An interaction between the wake and the separated shear-layr are visualized in a water channel. There is no separation when the pressure recovery coefficient attains the maximum.
(3) A new concept of a control device of separation is discussed. The separated shearlayr is controlled actively by using vortex rings ejected from outside flow region. Its application to a thin airfoil with separation is discussed in this study.
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Research Products
(14 results)
