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Baseline acoustic levels of the NASA Active Noise Control Fan rig

Author
Nallasamy, M.
Published
May 1996.
Physical Description
1 electronic document
Additional Creators
Heidelberg, Laurence J., Sutliff, Daniel L., and Elliott, David M.
Online Version

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Summary
Extensive measurements of the spinning acoustic mode structure in the NASA 48 inch Active Noise Control Fan (ANCF) test rig have been taken. A continuously rotating microphone rake system with a least-squares data reduction technique was employed to measure these modes in the inlet and exhaust. Farfield directivity patterns in an anechoic environment were also measured at matched corrected rotor speeds. Several vane counts and spacings were tested over a range of rotor speeds. The Eversman finite element radiation code was run with the measured in-duct modes as input and the computed farfield results were compared to the experimentally measured directivity pattern. The experimental data show that inlet spinning mode measurements can be made very accurately. Exhaust mode measurements may have wake interference, but the least-squares reduction does a good job of rejecting the non-acoustic pressure. The Eversman radiation code accurately extrapolates the farfield levels and directivity pattern when all in-duct modes are included.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19960027050.
Accession ID: 96N28545.
AIAA Paper 96-1745.
E-10231.
NASA-TM-107214.
NAS 1.26:107214.
Aeroacoustics Conference; 6-8 May 1996; State College, PA; United States.
Terms of Use and Reproduction
No Copyright.
View MARC record | catkey: 15650482