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Inlet noise suppressor design method based upon the distribution of acoustic power with mode cutoff ratioA liner design for noise suppressors with outer wall treatment such as in an engine inlet is presented which potentially circumvents the problems of resolution in modal measurement. The method is based on the fact that the modal optimum impedance and the maximum possible sound power attenuation at this optimum can be expressed as functions of cutoff ratio alone. Modes with similar cutoff ratios propagate similarly in the duct and in addition propagate similarly to the far field. Thus there is no need to determine the acoustic power carried by these modes individually, and they can be grouped together as one entity. With the optimum impedance and maximum attenuation specified as functions of cutoff ratio, the off-optimum liner performance can be estimated using an approximate attenuation equation.
Document ID
19770003369
Document Type
Conference Paper
Authors
Rice, E. J.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1976
Publication Information
Publication: Advan. in Eng. Sci., Vol. 3
Subject Category
Acoustics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19770003363Analytic PrimaryAdvances in Engineering Science, Volume 3