| Project/Area Number |
60550163
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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 |
Thermal engineering
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| Research Institution | Tokai University |
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Principal Investigator |
MURAKAMI Shuntaro Fuculty of Engineering, Tokai University, Associate Professor, 工学部, 助教授 (20055940)
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| Co-Investigator(Kenkyū-buntansha) |
HAGI Sanni Fuculty of Engineering, Tokai University, Professor, 工学部, 教授 (40055687)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Silencer / Expansion Chamber / Visualization / Flow Pattern / Chamber Length / Area Expansion Ratio / Mean Velocity / 平均速度 / 尾管共鳴 |
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| Research Abstract |
The air flow patterns in the silencers constructed a single expansion chamber were visualized by the tuft-grid methods and etc. Next the sound pressure leveles of the flow noise generated secondarily in the silencers were measured by using the very long tailpipe.
It is obvious from the results of these experiments that the frequency characteristics of the flow noise change with the flow pattern determined by the size of chambers. The peak values occur regardless of the tailpipe resonance, on a noise spectrum measured with each chamber of which length lc is smaller than four times of duct diameter d. The frequency fp at which a peak is highest may be predicted by Strouhal numbers(fp lc/V, V:mean flow velocity) arranged as the function of lc/d. The overall noise levels computed by using individual spectra obtained for many chambers are dependent on the geometric factors when lc/d lies between 2.5 and 6, but reduce with the decreasing area expansion ratio and the increasing chamber length in the range 6 < lc/d < 20.
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