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Determination of decay coefficients for combustors with acoustic absorbersAn analytical technique for the calculation of linear decay coefficients in combustors with acoustic absorbers is presented. Tuned circumferential slot acoustic absorbers were designed for the first three transverse modes of oscillation, and decay coefficients for these absorbers were found as a function of backing distance for seven different chamber configurations. The effectiveness of the absorbers for off-design values of the combustion response and acoustic mode is also investigated. Results indicate that for tuned absorbers the decay coefficient increases approximately as the cube of the backing distance. For most off-design situations the absorber still provides a damping effect. However, if an absorber designed for some higher mode of oscillation is used to damp lower mode oscillations, a driving effect is frequently found.
Document ID
19720007148
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Mitchell, C. E.
(Colorado State Univ. Fort Collins, CO, United States)
Espander, W. R.
(Colorado State Univ. Fort Collins, CO, United States)
Baer, M. R.
(Colorado State Univ. Fort Collins, CO, United States)
Date Acquired
September 2, 2013
Publication Date
January 1, 1972
Subject Category
Propulsion Systems
Report/Patent Number
NASA-CR-120836
Accession Number
72N14798
Funding Number(s)
CONTRACT_GRANT: NGR-06-002-095
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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