Multiple Pure Tone Noise Generated by Fans at Supersonic Tip Speeds
Author : T. G. Sofrin
Publisher :
Page : 23 pages
File Size : 16,60 MB
Release : 1970
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Author : T. G. Sofrin
Publisher :
Page : 23 pages
File Size : 16,60 MB
Release : 1970
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ISBN :
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 26 pages
File Size : 29,55 MB
Release : 2018-06-20
Category :
ISBN : 9781721570577
Fan noise continues to be a significant issue for commercial aircraft engines and there still exists a requirement for improved understanding of the fundamental issues associated with fan noise source mechanisms. At the present time, most of the prediction methods identify the dominant acoustic sources to be associated with the stator vanes or blade trailing edges which are downstream of the fan face. However recent studies have shown that acoustic waves are significantly attenuated as they propagate upstream through a rotor, and if the appropriate corrections are applied, sound radiation from the engine inlet is significantly underpredicted. The prediction models can only be applied to fans with subsonic tip speeds. In contrast, most aircraft engines have fan tip speeds which are transonic and this implies an even higher attenuation for upstream propagating acoustic waves. Consequently understanding how sound propagates upstream through the fan is an important, and not well understood phenomena. The objective of this study is to provide improved insight into the upstream propagation effects through a rotor which are relevant to full scale engines. The focus of this study is on broadband fan noise generated by boundary layer turbulence interacting with the trailing edges of the fan blades. If this source mechanism is important upstream of the fan, the sound must propagate upstream through a transonic non uniform flow which includes large gradients and non linearities. Developing acoustic propagation models in this type of flow is challenging and currently limited to low frequency applications, where the frequency is of the same order as the blade passing frequency of the fan. For trailing edge noise, much higher frequencies are relevant and so a suitable approach needs to be developed, which is not limited by an unacceptably large computational effort. In this study we are in the process of developing a computational method which applies for the high frequencies of
Author :
Publisher :
Page : 14 pages
File Size : 40,96 MB
Release : 2003
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Author :
Publisher :
Page : 642 pages
File Size : 49,66 MB
Release : 1977
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Author : B. Lakshminarayana
Publisher :
Page : 910 pages
File Size : 29,93 MB
Release : 1974
Category : Fluid mechanics
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Author : Arthur W. Goldstein
Publisher :
Page : 46 pages
File Size : 15,60 MB
Release : 1973
Category : Aerodynamics, Supersonic
ISBN :
Tests of supersonic rotors designed to reduce forward propagating pressure waves and the accompanying blade passing tones and multiple pure tones showed the wave propagation and noise reduction to have been obtained at the expense of increased noise radiation rearward. Outlet guide vanes served to muffle the noise propagating rearwards, but did not affect forward propagation at all.
Author : Gordon C. Oates
Publisher : AIAA
Page : 568 pages
File Size : 17,24 MB
Release : 1985
Category : Aerothermodynamics
ISBN : 9781600860058
Annotation Design and R & D engineers and students will value the comprehensive, meticulous coverage in this volume. Beginning with the basic principles and concepts of aeropropulsion combustion, chapters explore specific processes, limitations, and analytical methods as they bear on component design.
Author :
Publisher :
Page : 520 pages
File Size : 48,58 MB
Release : 1972
Category : Mechanics, Applied
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Author :
Publisher :
Page : 628 pages
File Size : 15,48 MB
Release : 1977
Category : Astronautics
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Author : Harvey H. Hubbard
Publisher :
Page : 616 pages
File Size : 48,34 MB
Release : 1991
Category : Aerodynamic noise
ISBN :