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Multimodal far-field acoustic radiation pattern : An approximate equation

Author
Rice, E. J.
Published
Oct 1, 1977.
Physical Description
1 electronic document
Online Version

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Summary
The far-field sound radiation theory for a circular duct was studied for both single mode and multimodal inputs. The investigation was intended to develop a method to determine the acoustic power produced by turbofans as a function of mode cut-off ratio. With reasonable simplifying assumptions the single mode radiation pattern was shown to be reducible to a function of mode cut-off ratio only. With modal cut-off ratio as the dominant variable, multimodal radiation patterns can be reduced to a simple explicit expression. This approximate expression provides excellent agreement with an exact calculation of the sound radiation pattern using equal acoustic power per mode.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19770025216.
Accession ID: 77N32160.
NASA-TM-73721.
Aeroacoustics Conf.; 3-5 Oct. 1977; Atlanta.
Terms of Use and Reproduction
No Copyright.
View MARC record | catkey: 15731243