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Jet Noise Prediction Comparisons with Scale Model Tests and Learjet Flyover DataRecent interest in commercial supersonic flight has highlighted the need to accurately predict Effective Perceived Noise Levels (EPNL) for aircraft and, since the dominant noise source at takeoff will likely be jet noise, specifically jet noise contributions. The current study compares predictions from historical jet-noise models within NASA’s Aircraft Noise Prediction Program and scale-model data to measurements made in a Learjet 25 flight test. The noise levels from the predictions and scale-model data were below those for the flight data by 2.5 – 3.5, 1 – 2, and 3 – 5 EPNdB for the SAE model, the Stone Jet model, and the scale-model data, respectively. Tones and broadband haystacks were identified in the flight spectra that are not associated with jet noise which increased the flight EPNL by at least 0.5 EPNdB over that computed from spectra with the tones and haystacks removed. The study highlights the need for accurate exhaust temperature measurements, aircraft flight position information, and averaging data across a line of microphones in flight tests. For example, a 100° F to 200° F difference in jet exhaust temperature is enough to explain the differences between flight, model scale, and prediction comparisons.
Document ID
20190025295
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Henderson, Brenda
(NASA Glenn Research Center Cleveland, OH, United States)
Huff, Dennis
(NASA Glenn Research Center Cleveland, OH, United States)
Berton, Jeff
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
May 23, 2019
Publication Date
May 20, 2019
Subject Category
Acoustics
Report/Patent Number
GRC-E-DAA-TN68049
Meeting Information
Meeting: AIAA/CEAS Aeroacoustics Conference
Location: Delft
Country: Netherlands
Start Date: May 20, 2019
End Date: May 23, 2019
Sponsors: American Institute of Aeronautics and Astronautics (AIAA)
Funding Number(s)
WBS: 110076.02.03.04.40.01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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