Aeroacoustic Analysis Of Fan Noise Reduction With Increased Bypass Nozzle Area

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781720372493
Total Pages : 34 pages
Book Rating : 4.97/5 ( download)

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Download or read book Aeroacoustic Analysis of Fan Noise Reduction with Increased Bypass Nozzle Area written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.Woodward, Richard P. and Hughes, Christopher E. and Podboy, Gary G.Glenn Research CenterAEROACOUSTICS; FAN BLADES; LOW SPEED WIND TUNNELS; NOZZLE FLOW; WIND TUNNEL TESTS; NOISE REDUCTION; AIRCRAFT ENGINES; BYPASSES; NOZZLE DESIGN; EFFECTIVE

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721683918
Total Pages : 24 pages
Book Rating : 4.17/5 ( download)

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Download or read book Noise Benefits of Increased Fan Bypass Nozzle Area written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced model turbofan (typical of current engine technology) was tested in the NASA Glenn 9 by 15 Foot Low Speed Wind Tunnel (9-by 15-Foot 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 for the engine at a high altitude, cruise point condition. However, the wind tunnel testing is conducted near sea level conditions. Therefore, in order to simulate and obtain performance at other aircraft operating conditions, two additional nozzles were designed and tested-one with a +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 conditions, 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 conditions. 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 several percentage points except fro the most open nozzle at takeoff rotor speed where stage performance decreased. These noise reduction benefits were seen to primarily affect broadband noise, and were evident throughout the range of measured sideline angles. Woodward, Richard P. and Hughes, Christopher E. Glenn Research Center NASA/TM-2004-213396, AIAA Paper 2005-1201, E-14899

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781719395397
Total Pages : 40 pages
Book Rating : 4.9X/5 ( download)

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Download or read book The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-22 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from the smallest to the largest nozzle was 12.9 percent of the baseline nozzle area. The results will show that there are significant changes in aerodynamic performance and farfield acoustics as the fan nozzle area is increased. The weight flow through the fan model increased between 7 and 9 percent, the fan and stage pressure dropped between 8 and 10 percent, and the adiabatic efficiency increased between 2 and 3 percent--the magnitude of the change dependent on the fan speed. Results from force balance measurements of fan and outlet guide vane thrust will show that as the nozzle exit area is increased the combined thrust of the fan and outlet guide vanes together also increases, between 2 and 3.5 percent, mainly due to the increase in lift from the outlet guide vanes. In terms of farfield acoustics, the overall sound power level produced by the fan stage dropped nearly linearly between 1 dB at takeoff condition and 3.5 dB at approach condition, mainly due to a decrease in the broadband n

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ISBN 13 :
Total Pages : 732 pages
Book Rating : 4.69/5 ( download)

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Download or read book Aerospace America written by and published by . This book was released on 2005 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.68/5 ( download)

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Download or read book Developmental Design, Fabrication, and Test of Acoustic Suppressors for Fans of High Bypass Turbofan Engines written by and published by . This book was released on 1974 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis procedure was developed for design of acoustically treated nacelles for high bypass turbofan engines. The plan was applied to the conceptual design of a nacelle for the quiet engine typical of a 707/DC-8 airplane installation. The resultant design was modified to a test nacelle design for the NASA Lewis quiet fan. The acoustic design goal was a 10 db reduction in effective perceived fan noise levels during takoff and approach. Detailed nacelle designs were subsequently developed for both the quiet engine and the quiet fan. The acoustic design goal for each nacelle was 15 db reductions in perceived fan noise levels from the inlet and fan duct. Acoustically treated nacelles were fabricated for the quiet engine and quiet fan for testing. Performance of selected inlet and fan duct lining configurations was experimentally evaluated in a flow duct. Results of the tests show that the linings perform as designed.

Author : David M. Elliott
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.30/5 ( download)

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Download or read book Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flight Conditions written by David M. Elliott and published by . This book was released on 2010 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Author : Harvey H. Hubbard
Publisher :
ISBN 13 :
Total Pages : 452 pages
Book Rating : 4.65/5 ( download)

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Download or read book Aeroacoustics of Flight Vehicles: Noise control written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721136438
Total Pages : 110 pages
Book Rating : 4.36/5 ( download)

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Download or read book Ultra-High Bypass Engine Aeroacoustic Study written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: A system study was carried out to identify potential advanced aircraft engine concepts and cycles which could be capable of achieving a 5 to 10 EPNdB reduction in community noise level relative to current FAR36 Stage 3 limits for a typical large-capacity commercial transport aircraft. The study was directed toward large twin-engine aircraft applications in the 400,000 to 500,000 pound take-off gross weight class. Four single rotation fan engine designs with fan pressure ratios from 1.3 to 1.75, and two counter-rotating fan engine configurations were studied. Several engine configurations were identified which, with further technology development, could achieve the objective of 5 to 10 EPNdB noise reduction. Optimum design fan pressure ratio is concluded to be in the range of 1.4 to 1.55 for best noise reduction with acceptable weight and Direct Operating Cost (DOC) penalties. Gliebe, Philip R. and Janardan, Bangalore A. Glenn Research Center NAS3-25269; WBS 22-781-30-12

Author : National Aeronautics and Space Administration (NASA)
Publisher :
ISBN 13 : 9781466499126
Total Pages : 28 pages
Book Rating : 4.25/5 ( download)

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Download or read book Acoustic Performance of Novel Fan Noise Reduction written by National Aeronautics and Space Administration (NASA) and published by . This book was released on 2010-11-01 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center's 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept.

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781719381772
Total Pages : 24 pages
Book Rating : 4.71/5 ( download)

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Download or read book Acoustic Performance of Novel Fan Noise Reduction Technologies for a High Bypass Model Turbofan at Simulated Flights Conditions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-22 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two novel fan noise reduction technologies, over the rotor acoustic treatment and soft stator vane technologies, were tested in an ultra-high bypass ratio turbofan model in the NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel. The performance of these technologies was compared to that of the baseline fan configuration, which did not have these technologies. Sideline acoustic data and hot film flow data were acquired and are used to determine the effectiveness of the various treatments. The material used for the over the rotor treatment was foam metal and two different types were used. The soft stator vanes had several internal cavities tuned to target certain frequencies. In order to accommodate the cavities it was necessary to use a cut-on stator to demonstrate the soft vane concept. Elliott, David M. and Woodward, Richard P. and Podboy, Gary G. Glenn Research Center ACOUSTIC PROPERTIES; AERODYNAMIC NOISE; TURBOFANS; NOISE REDUCTION; BYPASS RATIO; WIND TUNNELS; FAN BLADES; VANES