| Autor: |
Beckemeyer, R. J., Sawdy, D. T. |
| Zdroj: |
Journal of the Acoustical Society of America; 1976, Vol. 60 Issue S1, pS123-S123, 1p |
| Abstrakt: |
Low-frequency noise suppression in flow ducts can be achieved without excessive acoustic liner backing depth if the backing depth if the backing volume is formed as a long shallow cavity, folded so as to lie along the duct axis. Initial studies of such configurations revealed that sound transmission characteristics could not be accurately predicted when locally reacting impedance models were used. Consequently, an extended reaction model was developed for folded cavity liners by use of eigenfunction expansion techniques. Accuracy of the model has been verified by comparing analytical and experimental results for liners mounted in a 6-in.-square flow duct test facility. Several face sheet impedances and cavity geometries were tested at Mach numbers of 0.0 and 0.2 and frequencies from 500 to 1000 Hz. Good agreement was obtained between theoretical and experimental values of panel insertion loss as well as between analytical and measured duct centerline axial standing wave patterns. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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