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Assessment of Soft Vane and Metal Foam Engine Noise Reduction ConceptsTwo innovative fan-noise reduction concepts developed by NASA are presented - soft vanes and over-the-rotor metal foam liners. Design methodologies are described for each concept. Soft vanes are outlet guide vanes with internal, resonant chambers that communicate with the exterior aeroacoustic environment via a porous surface. They provide acoustic absorption via viscous losses generated by interaction of unsteady flows with the internal solid structure. Over-the-rotor metal foam liners installed at or near the fan rotor axial plane provide rotor noise absorption. Both concepts also provide pressure-release surfaces that potentially inhibit noise generation. Several configurations for both concepts are evaluated with a normal incidence tube, and the results are used to guide designs for implementation in two NASA fan rigs. For soft vanes, approximately 1 to 2 dB of broadband inlet and aft-radiated fan noise reduction is achieved. For over-the-rotor metal foam liners, up to 3 dB of fan noise reduction is measured in the low-speed fan rig, but minimal reduction is measured in the high-speed fan rig. These metal foam liner results are compared with a static engine test, in which inlet sound power level reductions up to 5 dB were measured. Brief plans for further development are also provided.
Document ID
20090020438
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Jones, Michael G. (NASA Langley Research Center Hampton, VA, United States)
Parrott, Tony L. (NASA Langley Research Center Hampton, VA, United States)
Sutliff, Daniel L. (NASA Glenn Research Center Cleveland, OH, United States)
Hughes, Chris (NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 24, 2013
Publication Date
May 11, 2009
Subject Category
Acoustics
Report/Patent Number
AIAA Paper 2009-3142
LF99-8002
Meeting Information
Meeting: 15th AIAA/CEAS Aeroacoustics Conference
Location: Miami, FL
Country: United States
Start Date: May 11, 2009
End Date: May 13, 2009
Sponsors: American Inst. of Aeronautics and Astronautics, National Oceanic and Atmospheric Administraion
Funding Number(s)
WBS: WBS 561581.02.08.07
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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