| Project/Area Number |
02650173
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械力学・制御工学
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| Research Institution | University of Tokyo |
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Principal Investigator |
KANEKO Shigehiko University of Tokyo, Fac. Eng., Associate Prof., 工学部, 助教授 (70143378)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Tatsuo University of Tokyo, Fac. Eng., Assistant, 工学部, 助手 (70011179)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1991: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Flow Induced Vibration / Self-Excited Vibration / Nuclear Reactor Component / Fast Breeder Reactor / Overflow Weir / Shell Vibration / Sloshing / Time Delay |
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| Research Abstract |
A new type of self-excited osillation due to the fluid discharge was observed during test operations of the Super Phenix LMFBR in France. Two types of instability modes were observed : one is the sloshing mode the meaning of which is the oscillation of a weir associated with both feeding and restitution collectors ; the other is hydroelastic mode the meaning of which is the osillation of a weir associated with fluid shell modes. In this investigation, the excitation mechanism of both modes is discussed both theoretically and experimentally. In the experiments, rectangular and annular tank were designed and manufactured to investigate the effect of fall hight and supply flow rate on the instability. Both sloshing and hydroelastic modes were observed in a rectangular tank. On the other band, only asloshing mode instability was observed in an annular tank. To establish the theory which can explain the mechanism of this instability, theoretical model was proposed. In this theory, basic equations are composed of the momentum equation of the downstream tank sloshing and conservation of supply flow rate. To formulate the fluid force colliding with free surface, momentum theory was employed. Finally, we succeeded in deriving the simplified governing equation of this instability. Theoretical results show the following ; (l)the frequency of this unstable oscillation is almost equal to the first natural frequency of the downstream tank sloshing, (2)unstable vibration can occur at the range of certain fall height, (3)the range of which becomes narrow with increasing supply flow rate. These theoretical results agree well with experimental results and the validity of the theory was confirmed.
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