NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsPerceived Noise Analysis for Offset Jets Applied to Commercial Supersonic AircraftA systems analysis was performed with experimental jet noise data, engineaircraft performance codes and aircraft noise prediction codes to assess takeoff noise levels and mission range for conceptual supersonic commercial aircraft. A parametric study was done to identify viable engine cycles that meet NASAs N+2 goals for noise and performance. Model scale data from offset jets was used as input to the aircraft noise prediction code to determine the expected sound levels for the lateral certification point where jet noise dominates over all other noise sources. The noise predictions were used to determine the optimal orientation of the offset nozzles to minimize the noise at the lateral microphone location. An alternative takeoff procedure called programmed lapse rate was evaluated for noise reduction benefits. Results show there are two types of engines that provide acceptable range performance; one is a standard mixed-flow turbofan with a single-stage fan, and the other is a three-stream variable-cycle engine with a multi-stage fan. The engine with a single-stage fan has a lower specific thrust and is 8 to 10 EPNdB quieter for takeoff. Offset nozzles reduce the noise directed toward the thicker side of the outer flow stream, but have less benefit as the core nozzle pressure ratio is reduced and the bypass-to-core area ratio increases. At the systems level for a three-engine N+2 aircraft with full throttle takeoff, there is a 1.4 EPNdB margin to Chapter 3 noise regulations predicted for the lateral certification point (assuming jet noise dominates). With a 10 reduction in thrust just after takeoff rotation, the margin increases to 5.5 EPNdB. Margins to Chapter 4 and Chapter 14 levels will depend on the cumulative split between the three certification points, but it appears that low specific thrust engines with a 10 reduction in thrust (programmed lapse rate) can come close to meeting Chapter 14 noise levels. Further noise reduction is possible with additional reduction in takeoff thrust using programmed lapse rate, but studies are needed to investigate the practical limits for safety and takeoff regulations.Document ID20190000928Acquisition SourceGlenn Research CenterDocument TypeTechnical Memorandum (TM)AuthorsHuff, Dennis L.*(NASA Glenn Research Center Cleveland, OH, United States)*Henderson, Brenda S.*(NASA Glenn Research Center Cleveland, OH, United States)*Berton, Jeffrey J.*(NASA Glenn Research Center Cleveland, OH, United States)*Seidel, Jonathan A.*(NASA Glenn Research Center Cleveland, OH, United States)*Date AcquiredFebruary 25, 2019Publication DateFebruary 1, 2019Subject CategoryAircraft Communications And NavigationReport/Patent NumberGRC-E-DAA-TN30595NASA/TM-2018-220049AIAA Paper 2016?1635Meeting InformationMeeting: SciTech 2016Location: San Diego, CACountry: United StatesStart Date: January 4, 2016End Date: January 8, 2016Sponsors:American Institute of Aeronautics and Astronautics (AIAA)Funding Number(s)WBS: WBS 110076.02.03.04.40.01Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.KeywordsJet NoiseAcousticTurbofansAvailable DownloadsNameType20190000928.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsIDRelationTitle20160004680See AlsoPerceived Noise Analysis for Offset Jets Applied to Commercial Supersonic Aircraftvisibility_offNo Preview Available
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