Noise Measurements from an Injector Suppressor Nozzle in the NASA Lewis 9x15 Ft Low Speed Wind Tunnel PDF Download
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Author: Eugene A. Krejsa
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Eugene A. Krejsa
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 66
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Book Description
Author: Adolph Atencio
Publisher:
ISBN:
Category : Jet planes
Languages : en
Pages : 72
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
Author: Richard P. Woodward
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 14
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Book Description
Author: Carl Lewis Jaeck
Publisher:
ISBN:
Category : Jet nozzles
Languages : en
Pages : 116
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Book Description
Author: Milo D. Dahl
Publisher:
ISBN:
Category : Acoustical engineering
Languages : en
Pages : 32
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 194
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781726184670
Category :
Languages : en
Pages : 34
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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: Nasa Technical Reports Server (Ntrs)
Publisher: BiblioGov
ISBN: 9781289277666
Category :
Languages : en
Pages : 26
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Book Description
Aircraft engine noise research and development depends on the ability to study and predict the noise created by each engine component in isolation. Fan noise testing, however, requires a significant support system including a drive mechanism to turn the fan, a device to smooth the flow into the fan, and a stand to raise the fan off the ground each of which has the potential to create its own noise. A methodology was therefore developed to improve the data quality for the 9x15 Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center that identifies three noise sources: fan noise, jet noise, and rig noise. The jet noise and rig noise was then measured by mounting a scale model of the 9x15 LSWT setup in a jet rig to simulate everything except the rotating machinery that characterizes fan noise. The data showed that the spectra measured in the LSWT has a strong rig noise component at frequencies as high as 3 kHz depending on the fan and speed. The jet noise was determined to be significantly lower than the rig noise. A mathematical model for the rig noise was then developed using a multi-dimensional least squares fit to the rig noise data. This allows the rig noise to be subtracted or removed, depending on the amplitude of the rig noise relative to the fan noise, at any given frequency, observer angle, or nozzle pressure ratio. The impact of isolating the fan noise with this method on spectra, overall power level (OAPWL), and Effective Perceived Noise Level (EPNL) is studied.
