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  • 1
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    Turbofan Noise Reduction Associated With Increased Bypass Nozzle Flow (2005)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: An advanced 22-in. scale model turbofan, typical of a current-generation aircraft engine design by GE Aircraft Engines, was tested in NASA Glenn Research Center s 9- by 15- Foot Low-Speed Wind Tunnel to explore the far-field acoustic effects of an increased bypass nozzle area at simulated aircraft speeds of takeoff, approach, and landing. The wind-tunnel-scale model consisted of the bypass stage fan, stators, and nacelle (including the fan exit nozzle) of a typical turbofan. This fan-stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry, which acquired aeroacoustic results over a range of test conditions. A baseline nozzle was selected, and the nozzle area was chosen for maximum performance at sea-level conditions. Two additional nozzles were also tested--one with a 5.4-percent increase in nozzle area over the baseline nozzle (sized for design point conditions), corresponding to a 5-percent increase in fan weight flow, and another nozzle with a 10.9-percent increase in nozzle area over the baseline nozzle (sized for maximum weight flow at sea-level conditions), corresponding to a 7.5 percent increase in fan weight flow. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level reductions of 2 dB or more (left graph) while the stage adiabatic efficiency (right graph) and thrust (final graph) actually increased by several percentage points. These noise-reduction benefits were seen to include both rotor-interaction tones and broadband noise, and were evident throughout the range of measured sideline angles.
    Keywords: Acoustics
    Type: Research and Technology 2004; NASA/TM-2005-213419
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Vibroacoustic Analysis of Large Heat Rejection Radiators for Future Spacecraft (2006)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Spacecraft structures such as antennas, solar arrays and radiator panels significantly respond to high acoustic levels seen at lift-off. Some future spacecraft may utilize nuclear electric propulsion that require large radiator panels to reject waste heat. A vibroacoustic assessment was performed for two different radiator panel designs. Results from the analysis of the two designs using different analytical approaches are presented and discussed.
    Keywords: Acoustics
    Type: Spacecraft and Launch Vehicle Dynamic Environment Workshop; Jun 21, 2005 - Jun 23, 2005; El Segundo, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Ultra High Bypass Ratio Engine Research for Reducing Noise, Emissions, and Fuel Consumption (2007)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A pictorial history of NASA development of advanced engine technologies for reducing environmental emissions and increasing performance from the 1970s to 2000s is presented. The goals of the Subsonic Fixed Wing Program portion of the NASA Fundamental Aeronautics Program are discussed, along with the areas of investigation currently being pursued by the Ultra High Bypass Partnership Element of the Subsonic Fixed Wing Program.
    Keywords: Acoustics
    Type: Fundamental Aeronautics 2007 Annual Meeting; Oct 30, 2007 - Nov 01, 2007; New Orleans, LA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Assessment of Soft Vane and Metal Foam Engine Noise Reduction Concepts (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two innovative fan-noise reduction concepts developed by NASA are presented - soft vanes and over-the-rotor metal foam liners. Design methodologies are described for each concept. Soft vanes are outlet guide vanes with internal, resonant chambers that communicate with the exterior aeroacoustic environment via a porous surface. They provide acoustic absorption via viscous losses generated by interaction of unsteady flows with the internal solid structure. Over-the-rotor metal foam liners installed at or near the fan rotor axial plane provide rotor noise absorption. Both concepts also provide pressure-release surfaces that potentially inhibit noise generation. Several configurations for both concepts are evaluated with a normal incidence tube, and the results are used to guide designs for implementation in two NASA fan rigs. For soft vanes, approximately 1 to 2 dB of broadband inlet and aft-radiated fan noise reduction is achieved. For over-the-rotor metal foam liners, up to 3 dB of fan noise reduction is measured in the low-speed fan rig, but minimal reduction is measured in the high-speed fan rig. These metal foam liner results are compared with a static engine test, in which inlet sound power level reductions up to 5 dB were measured. Brief plans for further development are also provided.
    Keywords: Acoustics
    Type: AIAA Paper 2009-3142 , LF99-8002 , 15th AIAA/CEAS Aeroacoustics Conference; May 11, 2009 - May 13, 2009; Miami, FL; United States
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  • 5
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    Aeroacoustic Analysis of Fan Noise Reduction With Increased Bypass Nozzle Area (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An advanced model turbofan was tested in the NASA Glenn 9-by 15-Foot Low Speed Wind Tunnel (9x15 LSWT) to explore far field acoustic effects of increased bypass nozzle area. This fan stage test was part of the NASA Glenn Fan Broadband Source Diagnostic Test, second entry (SDT2) which acquired aeroacoustic results over a range of test conditions. The baseline nozzle was sized to produce maximum stage performance at cruise condition. However, the wind tunnel testing is conducted near sea level condition. Therefore, in order to simulate and obtain performance at other operating conditions, two additional nozzles were designed and tested one with +5 percent increase in weight flow (+5.4 percent increase in nozzle area compared with the baseline nozzle), sized to simulate the performance at the stage design point (takeoff) condition, and the other with a +7.5 percent increase in weight flow (+10.9 percent increase in nozzle area) sized for maximum weight flow with a fixed nozzle at sea level condition. Measured acoustic benefits with increased nozzle area were very encouraging, showing overall sound power level (OAPWL) reductions of 2 or more dB while the stage thrust actually increased by 2 to 3 percent except for the most open nozzle at takeoff rotor speed where stage performance decreased. Effective perceived noise levels for a 1500 ft engine flyover and 3.35 scale factor showed a similar noise reduction of 2 or more EPNdB. Noise reductions, principally in the level of broadband noise, were observed everywhere in the far field. Laser Doppler Velocimetry measurements taken downstream of the rotor showed that the total turbulent velocity decreased with increasing nozzle flow, which may explain the reduced rotor broadband noise levels.
    Keywords: Acoustics
    Type: NASA/TM-2005-213825 , E-15184 , AIAA Paper 2005-3075 , 11th Aeroacoustics Conference cosponsored by the American Institute of Aeronautics and Astronautics and the Confederation of European Aerospace Societies; May 23, 2005 - May 25, 2005; Monterey, CA; United States
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    NASA TECHNICAL REPORTS
  • 6
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    Collaborative Research on the Ultra High Bypass Ratio Engine Cycle to Reduce Noise, Emissions and Fuel Consumption (2008)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A pictorial history of NASA development of advanced engine technologies for reducing environmental emissions and increasing performance from the 1970s to present is presented. The goals of the Subsonic Fixed Wing Program portion of the NASA Fundamental Aeronautics Program are addressed, along with the areas of investigation currently being pursued by the Ultra High Bypass Partnership Element of the Subsonic Fixed Wing Program to meet the goals. Ultra High Bypass cycle research collaboration successes with Pratt & Whitney are presented.
    Keywords: Acoustics
    Type: E-16711 , UTIAS-MITACS International Workshop on Aviation and Climate Change; May 29, 2008 - May 30, 2008; Toronto; Canada
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Overview of the Orion Vibroacoustic Test Capability at NASA Glenn Research Center (2008)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In order to support the environmental test needs for our new Orion and Constellation program, NASA is developing unique world-class test facilities. To optimize this testing of spaceflight hardware while minimizing transportation issues, a one-stop, under one roof test capability is being developed at the Space Power Facility at the NASA Glenn Research Center's Plum Brook Station. This facility will provide the capability to perform the following environmental testing: (1) reverberation acoustic testing, (2) mechanical base-shake sine testing, (3) modal testing, (4) thermal-vacuum testing, and (5) EMI/EMC (electromagnetic interference and compatibility) testing. An overview of this test capability will be provided in this presentation, with special focus on the two new vibroacoustic test facilities currently being designed and built, the Reverberant Acoustic Test Facility (RATF) and the Mechanical Vibration Facility (MVF). Testing of the engineering developmental hardware and qualification hardware of the Orion (Crew Exploration Vehicle) will commence shortly after the facilities are commissioned.
    Keywords: Acoustics
    Type: E-16712 , E-16713 , ESTECH 2008; May 04, 2008 - May 07, 2008; Bloomingdale, IL; United States|Spacecraft and Launch Vehicle Dynamic Environments Workshop; Jun 10, 2008 - Jun 12, 2008; El Segundo, CA; United States
    Format: application/pdf
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