1990 Fiscal Year Final Research Report Summary
The Study of Sound Propagation and Radiation of a Circular Duct with Flow ( An Analysis Using Wiener-Hopf Method)
| Project/Area Number |
01550768
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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 |
応用物理学一般(含航海学)
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| Research Institution | Kagoshima University |
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Principal Investigator |
YUNOKI Keni'chi Kagoshima University, Faculty of Engineering, Assistant, 工学部, 助手 (00041541)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Circular duct / Flow / Sound wave / Wiener-Hopf method / Sound reflection / Sound radiation |
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| Research Abstract |
The purpose of this study is to apply Wiener-Hopf method to a semi-infinite circular. Hard-walled or sound-absorbing or varying cross-sectional, duct with flow. Another purpose is to measure minitely sound and air flow in each circular duct.
The values of split function were calculated for a circular duct without flow by using the computer IBM 3081-K32. And, split function with flow is calculated from one without flow and the equation derived by G. W. Johnstone and his follower (J. A. S. A 1980).
The eigenvalue equation is shown for a sound-absorbing duct with flow. Especially a calculating method and results of the eigen value equation are obtained for its duct without flow. And attenuation contour against admittance is shown.
By applying Okuda's Analysis (J. A. S. J. 1969) and Jeong-Guon Ih's one. Expansion chamber type mufflers with flow are solved rigorously. And, by applying Murakami's analysis (J. S. M. E. 1982), transmission loss and insertion loss can be calculated for a circular duct composed of several horns with flow.
Measurement using impulse signal, M-sequence signal and so on were established. It is evident that the method of J. Y. Chung and his follower (J. A. S. A. 1980) is effective to the measurement of a circular duct with flow. Also, by hot wire flow measurement system, sound and air flow of a circular duct are able to measure minitely.
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