NDLI: Baseline acoustic levels of the nasa active noise control fan rig

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Baseline acoustic levels of the nasa active noise control fan rig

Content Provider	NASA Technical Reports Server (NTRS)
Author	Heidelberg, Laurence J. Sutliff, Daniel L. Elliott, David M. Nallasamy, M.
Copyright Year	1996
Description	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.
File Size	1532293
Page Count	30
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19960027050
Archival Resource Key	ark:/13960/t3324w02g
Language	English
Publisher Date	1996-05-01
Access Restriction	Open
Subject Keyword	Acoustics Finite Element Method Ducted Fans Acoustic Measurement Acoustic Properties Noise Reduction Aerodynamic Interference Aerodynamic Noise Sound Pressure Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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