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Open Rotor Aeroacoustic Installation Effects for Conventional and Unconventional AirframesAs extensive experimental campaign was performed to study the aeroacoustic installation effects of an open rotor with respect to both a conventional tube and wing type airframe and an unconventional hybrid wing body airframe. The open rotor rig had two counter rotating rows of blades each with eight blades of a design originally flight tested in the 1980s. The aeroacoustic installation effects measured in an aeroacoustic wind tunnel included those from flow effects due to inflow distortion or wake interaction and acoustic propagation effects such as shielding and reflection. The objective of the test campaign was to quantify the installation effects for a wide range of parameters and configurations derived from the two airframe types. For the conventional airframe, the open rotor was positioned in increments in front of and then over the main wing and then in positions representative of tail mounted aircraft with a conventional tail, a T-tail and a U-tail. The interaction of the wake of the open rotor as well as acoustic scattering results in an increase of about 10 dB when the rotor is positioned in front of the main wing. When positioned over the main wing a substantial amount of noise reduction is obtained and this is also observed for tail-mounted installations with a large U-tail. For the hybrid wing body airframe, the open rotor was positioned over the airframe along the centerline as well as off-center representing a twin engine location. A primary result was the documentation of the noise reduction from shielding as a function of the location of the open rotor upstream of the trailing edge of the hybrid wing body. The effects from vertical surfaces and elevon deflection were also measured. Acoustic lining was specially designed and inserted flush with the elevon and airframe surface, the result was an additional reduction in open rotor noise propagating to the far field microphones. Even with the older blade design used, the experiment provided quantification of the aeroacoustic installation effects for a wide range of open rotor and airframe configurations and can be used with data processing methods to evaluate the aeroacoustic installation effects for open rotors with modern blade designs.
Document ID
20130013993
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Czech, Michael J.
(Boeing Co. Everett, WA, United States)
Thomas, Russell H.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 27, 2013
Publication Date
May 27, 2013
Subject Category
Acoustics
Report/Patent Number
AIAA Paper 2013-2185
NF1676L-15865
Meeting Information
Meeting: 19th AIAA/CEAS Aeroacoustics Conference
Location: Berlin
Country: Germany
Start Date: May 27, 2013
End Date: May 29, 2013
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 699959.02.10.07.05
Distribution Limits
Public
Copyright
Public Use Permitted.
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