| Project/Area Number |
09650193
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
AOKI Toshiyuki Kyushu University, Graduate School of Engineering Sciences, Associate Professor, 大学院・総合理工学研究科, 助教授 (20150922)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1997: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | High Speed Train / Tunnel / Micro-Pressure Wave / Passive Control / Pressure Wave / Unsteady Flow / Interaction / Noise Reduction / パッシプコントロール / 高速列車 / 騒音 / 圧縮波 / 衝撃波 |
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| Research Abstract |
Simple expansion chambers close to a tunnel exit portal can cause significant reductions in the amplitudes of micro-pressure waves propagating outside the tunnel.
1. The optimum shape of such chambers depends upon the steepness of the reflecting wavefront. Greatest percentage reductions are achieved for the steepest wavefronts.
2. When a range of steepnesses of incident wavefronts is expected, the chamber shape should be optimized for the steepest case that is considered feasible. This will provide greatest benefit when it is most needed. In most cases, this shape will also perform well with less steep wavefronts even though it is not optimum.
3. For any particular incident wavefront steepness, the optimum shape of the chambers is dependent on the chamber size. For the steep wavefronts of greatest relevance herein, however, the dependence is not strong.
4. Typically, a well-designed chamber with a unit volume of tunnel may cause a reduction of about 30% in the magnitudes of micro-pressure waves. This is in addition to reductions resulting from other modifications (e.g., at the tunnel entry).
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