Summary of forward velocity effects on fan noise [PDF]
Available experimental data comparing the in-flight and static behavior of fan noise are reviewed. These results are then compared with recent data obtained for a fan stage tested with forward velocity in a low speed wind tunnel.
Feiler, C. E., Groeneweg, J. F.
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An evaluation of some alternative approaches for reducing fan tone noise [PDF]
The potential of two alternative approaches for reducing fan ton noise was investigated in this study. One of these approaches increases the number of rotor blades to shift the tone noise to higher frequencies that are not rated as strongly by the ...
Dittmar, James H., Woodward, Richard P.
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Coannular nozzle noise characteristics and application to advanced supersonic transport engines [PDF]
Recent programs in the field of jet noise, sponsored by the NASA Lewis Research Center, have indicated that the variable stream control engines (VSCE) which are being considered for advanced supersonic cruise aircraft have inherent jet noise advantages ...
Kozlowski, H.
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LF336 lift fan modification and acoustic test program [PDF]
Investigating lift fan noise reduction by configuration modifications in LF336/
Kazin, S. B., Volk, L. J.
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Noise comparisons of single and two stage demonstrator fans for advanced technology aircraft [PDF]
A high-speed single-stage and a low-speed two-stage fan were designed, fabricated, and tested to demonstrate their predicted low noise performance for an advanced 0.85-0.90 cruise Mach number aircraft requiring a 1.8-1.9 pressure ratio fan.
Heidmann, M. F.
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Forward acoustic performance of a shock-swallowing high-tip-speed fan (QF-13) [PDF]
Forward noise and overall aerodynamic performance data are presented for a high-tip-speed fan having rotor blade airfoils designed to alter the conventional leading-edge bow shocks to weak, oblique shocks which are swallowed within the interblade ...
Lucas, J. G. +2 more
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Refan program. Phase 1: Summary report [PDF]
The Refan Program is aimed at a large reduction in aircraft approach and takeoff noise in the vicinity of airports caused by the JT3D-powered 707's and DC-8's and the JT8D-powered 727's, 737's and DC-9's.
Bresnahan, D. L., Sams, E. W.
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Study of the Noise Reduction Mechanism of Bionic Circular Arch Structures on the Blades of a High-Volumetric-Airflow Axial Flow Fan. [PDF]
Biomimetics (Basel)Shen C +5 more
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Preliminary core-engine noise abatement experimental results of a fluid injection nozzle on a JT-15D turbofan engine [PDF]
Jet noise, as induced by shear stress, in an jet exhaust is investigated. Experiments were performed on a JT-15D fan jet to verify the inward momentum stress reduction concept.
Cheng, D. Y., Wang, P.
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