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Open Rotor Tone Shielding Methods for System Noise Assessments Using Multiple DatabasesAdvanced aircraft designs such as the hybrid wing body, in conjunction with open rotor engines, may allow for significant improvements in the environmental impact of aviation. System noise assessments allow for the prediction of the aircraft noise of such designs while they are still in the conceptual phase. Due to significant requirements of computational methods, these predictions still rely on experimental data to account for the interaction of the open rotor tones with the hybrid wing body airframe. Recently, multiple aircraft system noise assessments have been conducted for hybrid wing body designs with open rotor engines. These assessments utilized measured benchmark data from a Propulsion Airframe Aeroacoustic interaction effects test. The measured data demonstrated airframe shielding of open rotor tonal and broadband noise with legacy F7/A7 open rotor blades. Two methods are proposed for improving the use of these data on general open rotor designs in a system noise assessment. The first, direct difference, is a simple octave band subtraction which does not account for tone distribution within the rotor acoustic signal. The second, tone matching, is a higher-fidelity process incorporating additional physical aspects of the problem, where isolated rotor tones are matched by their directivity to determine tone-by-tone shielding. A case study is conducted with the two methods to assess how well each reproduces the measured data and identify the merits of each. Both methods perform similarly for system level results and successfully approach the experimental data for the case study. The tone matching method provides additional tools for assessing the quality of the match to the data set. Additionally, a potential path to improve the tone matching method is provided.
Document ID
20140007355
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Bahr, Christopher J.
(NASA Langley Research Center Hampton, VA, United States)
Thomas, Russell H.
(NASA Langley Research Center Hampton, VA, United States)
Lopes, Leonard V.
(NASA Langley Research Center Hampton, VA, United States)
Burley, Casey L.
(NASA Langley Research Center Hampton, VA, United States)
Van Zante, Dale E.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
June 12, 2014
Publication Date
January 13, 2014
Subject Category
Acoustics
Aerodynamics
Aircraft Design, Testing And Performance
Report/Patent Number
AIAA Paper-2014-0367
NF1676L-16694
Meeting Information
Meeting: AIAA Aerospace Sciences Meeting
Location: National Harbor, MD
Country: United States
Start Date: January 13, 2014
End Date: January 17, 2014
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 699959.02.10.07.06
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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