Broadband Rotor Noise Analysis PDF Download
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Author: Albert R. George
Publisher:
ISBN:
Category :
Languages : en
Pages : 98
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Book Description
Author: Albert R. George
Publisher:
ISBN:
Category :
Languages : en
Pages : 98
Get Book Here
Book Description
Author: Albert R. George
Publisher:
ISBN:
Category : Rotors
Languages : en
Pages : 104
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Book Description
Author: Albert R. George
Publisher:
ISBN:
Category : Rotors
Languages : en
Pages : 104
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Book Description
Author: Albert R. George
Publisher:
ISBN:
Category :
Languages : en
Pages : 52
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 192
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Book Description
Author: Thomas F. Brooks
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: James Scheiman
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 68
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Book Description
Author: Qidou Zhou
Publisher:
ISBN:
Category :
Languages : en
Pages : 199
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Book Description
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723944666
Category : Science
Languages : en
Pages : 98
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Book Description
This report examines the effects on broadband noise generation of unsteady coupling between a rotor and stator in the fan stage of a turbofan engine. Whereas previous acoustic analyses treated the blade rows as isolated cascades, the present work accounts for reflection and transmission effects at both blade rows by tracking the mode and frequency scattering of pressure and vortical waves. The fan stage is modeled in rectilinear geometry to take advantage of a previously existing unsteady cascade theory for 3D perturbation waves and thereby use a realistic 3D turbulence spectrum. In the analysis, it was found that the set of participating modes divides itself naturally into "independent mode subsets" that couple only among themselves and not to the other such subsets. This principle is the basis for the analysis and considerably reduces computational effort. It also provides a simple, accurate scheme for modal averaging for further efficiency. Computed results for a coupled fan stage are compared with calculations for isolated blade rows. It is found that coupling increases downstream noise by 2 to 4 dB. Upstream noise is lower for isolated cascades and is further reduced by including coupling effects. In comparison with test data, the increase in the upstream/downstream differential indicates that broadband noise from turbulent inflow at the stator dominates downstream noise but is not a significant contributor to upstream noise.Hanson, Donald B.Glenn Research CenterTURBOFAN ENGINES; ENGINE NOISE; ROTOR STATOR INTERACTIONS; NOISE MEASUREMENT; TURBULENT FLOW; SIGNAL ANALYZERS; ACOUSTIC COUPLING; SOUND TRANSMISSION; WAVE REFLECTION; BROADBAND
Author: Donald B. Hanson
Publisher: BiblioGov
ISBN: 9781289273941
Category :
Languages : en
Pages : 100
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Book Description
This report examines the effects on broadband noise generation of unsteady coupling between a rotor and stator in the fan stage of a turbofan engine. Whereas previous acoustic analyses treated the blade rows as isolated cascades, the present work accounts for reflection and transmission effects at both blade rows by tracking the mode and frequency scattering of pressure and vortical waves. The fan stage is modeled in rectilinear geometry to take advantage of a previously existing unsteady cascade theory for 3D perturbation waves and thereby use a realistic 3D turbulence spectrum. In the analysis, it was found that the set of participating modes divides itself naturally into "independent mode subsets" that couple only among themselves and not to the other such subsets. This principle is the basis for the analysis and considerably reduces computational effort. It also provides a simple, accurate scheme for modal averaging for further efficiency. Computed results for a coupled fan stage are compared with calculations for isolated blade rows. It is found that coupling increases downstream noise by 2 to 4 dB. Upstream noise is lower for isolated cascades and is further reduced by including coupling effects. In comparison with test data, the increase in the upstream/downstream differential indicates that broadband noise from turbulent inflow at the stator dominates downstream noise but is not a significant contributor to upstream noise.
