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An evaluation of active noise control in a cylindrical shellThe physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell are discussed. Measured data was compared with computer results from a previously derived analytical model based on an infinite shell theory. For both the analytical model and experiment, the radiation of the external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic cylindrical shell. An active noise control system was implemented in the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over the entire length of the experimental model. Results indicate that for extended axial forcing distributions or very low shell damping, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section.
Document ID
19890060349
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Silcox, R. J.
(NASA Langley Research Center Hampton, VA, United States)
Lester, H. C.
(NASA Langley Research Center Hampton, VA, United States)
Abler, S. B.
(NASA Langley Research Center; Joint Institute for Advancement of Flight Sciences Hampton, VA, United States)
Date Acquired
August 14, 2013
Publication Date
July 1, 1989
Publication Information
Publication: ASME, Transactions, Journal of Vibration, Acoustics, Stress, and Reliability in Design
Volume: 111
ISSN: 0739-3717
Subject Category
Acoustics
Accession Number
89A47720
Distribution Limits
Public
Copyright
Other

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