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TITLE AND SUBTITLE:
Rotating Rake Mode Measurements Over Passive Treatment in a Ducted Fan
AUTHOR(S):
Sutliff, Daniel, L.
REPORT DATE:
2006-12-XX
FUNDING NUMBERS:
WBS 561581.02.08.03.18.03
PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration John H. Glenn Research Center at Lewis Field Cleveland, Ohio 44135-3191
PERFORMING ORGANIZATION REPORT NUMBER:
E-15785
SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration Washington, DC 20546-0001
REPORT TYPE AND DATES COVERED:
Technical Memorandum
SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA/TM-2006-214493
SUPPLEMENTARY NOTES:
Prepared for the 35th International Congress and Exposition on Noise Control Engineering (INTER-NOISE 2006) sponsored by the International Institute of Noise Control Engineering, Honolulu, Hawaii, December 3-6, 2006. Responsible, Daniel L. Sutliff, organization code RTA, 216-433-6290.
ABSTRACT:
The NASA Glenn Research Center's Rotating Rake mode measurement system has been successful in measuring the modal content propagating in hardwall ducts. This paper proposes an extension of the Rotating Rake measurement and analysis technique to treated sections by developing basis functions based on wall impedance boundary conditions for flow conditions (i.e., constant duct area and Mach number) where the closed form analytical solution exists. Analytical equations developed to estimate mode power are incorporated. This method is verified by decomposing and analyzing radial pressure profiles generated numerically by the Eversman propagation code. Several modes, frequencies and impedances are evaluated. Data from a low-speed ducted fan with several different impedance conditions was acquired and reduced to determine the best fit to the data. Using the impedance boundary conditions result in better mode measurement solutions.
SUBJECT TERMS:
Aeroacoustics; Liners; Ducted fans
NUMBER OF PAGES:
18
PDF AVAILABLE FROM URL:
2006/TM-2006-214493.pdf ( 4692 KB )
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