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Solution of the wave equation for open surfaces involving a line integral over the edgeA simple mathematical model of a stationary source distribution for the supersonic-propeller noise-prediction formula of Farassat (1983) is developed to test the validity of the formula solutions. The conventional thickness source term is used in place of the Isom thickness formula; the relative importance of the line and surface integrals in the solutions is evaluated; and the numerical results are compared with those obtained with a conventional retarded-time solution in tables. Good agreement is obtained over elevation angles from 10 to 90 deg, and the line-integral contribution is found to be significant at all elevation angles and of the same order of magnitude as the surface-integral contribution at angles less than 30 deg. The amplitude-normalized directivity patterns for the four cases computed (x = 1.5 or 10; k = 5.0 or 50) are presented graphically.
Document ID
19840062877
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Farassat, F.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 12, 2013
Publication Date
July 8, 1984
Publication Information
Publication: Journal of Sound and Vibration
Volume: 95
ISSN: 0022-460X
Subject Category
Acoustics
Accession Number
84A45664
Distribution Limits
Public
Copyright
Other

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