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Measurement of angular distribution of sound emission from training projectiles in subsonic flightTraining projectiles with nose ring cavities that produce intense whistles in stationary free-jet tests were shot in a relatively straight-line trajectory. A ground based microphone was used to obtain the angular distribution of sound intensity produced from the subsonically flying projectile. Data reduction required calculation of Doppler and attenuation factors which were determined based on a non-linear trajectory. Also, the directional sensitivity of the microphone was measured and used in the data reduction. Significant angular variation of sound intensity produced from the projectile was found which can be used to plot an intensity contour map on the ground. A full-scale field test confirmed the validity of the aeroacoustic concept of producing a relatively intense whistle from the projectile, and the usefulness of a real-time data acquisition system.
Document ID
19860035187
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Cho, Y. I.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Parthasarathy, S. P.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Harstad, K. G.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Back, L. H.
(California Institute of Technology Jet Propulsion Laboratory, Pasadena, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1986
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 86-0516
Accession Number
86A19925
Distribution Limits
Public
Copyright
Other

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