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Effects of blade-vane ratio and rotor-stator spacing on fan noise with forward velocityA research fan stage is acoustically tested in an anechoic wind tunnel with a 41 m/sec tunnel flow. Two stator vane numbers giving cut-on and cut-off conditions are tested at three rotor stator spacings ranging from 0.5 to 2.0 rotor chords. Hot-film anemometer turbulence measurements are made at the leading edge of the stator for each spacing, and a crossed film anemometer is radially transversed to define streamwise and upwash characteristics of the rotor blade wakes. Trends in the acoustic results are observed in the front and aft quadrants at 80% design fan speed. Aft quadrant results demonstrate a fundamental tone 9 dB lower for the 25 vane stator than for the 11 vane stator, while overtone levels are 3 dB higher. The cut-off criterion strongly controls fundamental tone level at all spacings, and spacing trends of the wake-defect upwash component show good agreement with corresponding cut-on acoustic tone levels.
Document ID
19810064224
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Woodward, R. P.
(NASA Lewis Research Center Cleveland, OH, United States)
Glaser, F. W.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 11, 2013
Publication Date
October 1, 1981
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
AIAA PAPER 81-2032
Meeting Information
Meeting: Aeroacoustics Conference
Location: Palo Alto, CA
Start Date: October 5, 1981
End Date: October 7, 1981
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
81A48628
Distribution Limits
Public
Copyright
Other

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