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Jet-noise reduction through liquid-base foam injection.An experimental investigation has been made of the sound-absorbing properties of liquid-base foams and of their ability to reduce jet noise. Protein, detergent, and polymer foaming agents were used in water solutions. A method of foam generation was developed to permit systematic variation of the foam density. The investigation included measurements of sound-absorption coefficents for both plane normal incidence waves and diffuse sound fields. The intrinsic acoustic properties of foam, e.g., the characteristic impedance and the propagation constant, were also determined. The sound emitted by a 1-in.-diam cold nitrogen jet was measured for subsonic (300 m/sec) and supersonic (422 m/sec) jets, with and without foam injection. Noise reductions up to 10 PNdB were measured.
Document ID
19720026494
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Manson, L.
Burge, H. L.
(TRW Systems Group Redondo Beach, Calif., United States)
Date Acquired
August 6, 2013
Publication Date
October 1, 1971
Publication Information
Publication: Acoustical Society of America
Subject Category
Propulsion Systems
Accession Number
72A10160
Funding Number(s)
CONTRACT_GRANT: NAS1-9425
Distribution Limits
Public
Copyright
Other

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