Theory For Broadband Noise Of Rotor And Stator Cascades With Inhomogeneous Inflow Turbulence Including Effects Of Lean And Sweep
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Theory For Broadband Noise Of Rotor And Stator Cascades With Inhomogeneous Inflow Turbulence Including Effects Of Lean And Sweep
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Author :
language : en
Publisher:
Release Date : 2001
Theory For Broadband Noise Of Rotor And Stator Cascades With Inhomogeneous Inflow Turbulence Including Effects Of Lean And Sweep written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Theory For Broadband Noise Of Rotor And Stator Cascades With Inhomogeneous Inflow Turbulence Including Effects Of Lean And Sweep
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Author : National Aeronautics and Space Adm Nasa
language : en
Publisher: Independently Published
Release Date : 2018-09-24
Theory For Broadband Noise Of Rotor And Stator Cascades With Inhomogeneous Inflow Turbulence Including Effects Of Lean And Sweep written by National Aeronautics and Space Adm Nasa and has been published by Independently Published this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-24 with Science categories.
The problem of broadband noise generated by turbulence impinging on a downstream blade row is examined from a theoretical viewpoint. Equations are derived for sound power spectra in terms of 3 dimensional wavenumber spectra of the turbulence. Particular attention is given to issues of turbulence inhomogeneity associated with the near field of the rotor and variations through boundary layers. Lean and sweep of the rotor or stator cascade are also handled rigorously with a full derivation of the relevant geometry and definitions of lean and sweep angles. Use of the general theory is illustrated by 2 simple theoretical spectra for homogeneous turbulence. Limited comparisons are made with data from model fans designed by Pratt & Whitney, Allison, and Boeing. Parametric studies for stator noise are presented showing trends with Mach number, vane count, turbulence scale and intensity, lean, and sweep. Two conventions are presented to define lean and sweep. In the "cascade system" lean is a rotation out of its plane and sweep is a rotation of the airfoil in its plane. In the "duct system" lean is the leading edge angle viewing the fan from the front (along the fan axis) and sweep is the angle viewing the fan from the side (, perpendicular to the axis). It is shown that the governing parameter is sweep in the plane of the airfoil (which reduces the chordwise component of Mach number). Lean (out of the plane of the airfoil) has little effect. Rotor noise predictions are compared with duct turbulence/rotor interaction noise data from Boeing and variations, including blade tip sweep and turbulence axial and transverse scales are explored.Hanson, Donald B.Glenn Research CenterINTERACTIONAL AERODYNAMICS; ROTORS; STATORS; CASCADE FLOW; TURBOFAN ENGINES; HOMOGENEOUS TURBULENCE; NOISE PREDICTION; ENGINE NOISE; POWER SPECTRA; LEADING EDGES; DUCTS; BROADBAND; BLADE TIPS; AIRFOILS; BOUNDARY LAYERS; MACH NUMBER; SWEEP ANGLE
Broadband Noise Of Fans With Unsteady Coupling Theory To Account For Rotor And Stator Reflection Transmission Effects
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Author :
language : en
Publisher:
Release Date : 2001
Broadband Noise Of Fans With Unsteady Coupling Theory To Account For Rotor And Stator Reflection Transmission Effects written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
The Journal Of The Acoustical Society Of America
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Author : Acoustical Society of America
language : en
Publisher:
Release Date : 2006
The Journal Of The Acoustical Society Of America written by Acoustical Society of America and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Acoustical engineering categories.
Aiaa Journal
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Author : American Institute of Aeronautics and Astronautics
language : en
Publisher:
Release Date : 2006
Aiaa Journal written by American Institute of Aeronautics and Astronautics and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Aeronautics categories.
Monthly Catalog Of United States Government Publications
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Author :
language : en
Publisher:
Release Date : 2002-07
Monthly Catalog Of United States Government Publications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-07 with Government publications categories.
Broadband Noise Of Fans With Unsteady Coupling Theory To Account For Rotor And Stator Reflection Transmission Effects
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Author : National Aeronautics and Space Adm Nasa
language : en
Publisher: Independently Published
Release Date : 2018-09-23
Broadband Noise Of Fans With Unsteady Coupling Theory To Account For Rotor And Stator Reflection Transmission Effects written by National Aeronautics and Space Adm Nasa and has been published by Independently Published this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-23 with Science categories.
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
Broadband Noise Of Fans
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Author : Donald B. Hanson
language : en
Publisher: BiblioGov
Release Date : 2013-08
Broadband Noise Of Fans written by Donald B. Hanson and has been published by BiblioGov this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-08 with categories.
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.
Broadband Noise Generated By Turbulent Inflow To Rotor Or Stator Blades In An Annular Duct
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Author : Frank Lane
language : en
Publisher:
Release Date : 1975
Broadband Noise Generated By Turbulent Inflow To Rotor Or Stator Blades In An Annular Duct written by Frank Lane and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1975 with Turbomachines categories.
The Green's function relating the radiated pressure field to the fluctuating forces on rotor or stator blades is developed in the presence of dissipation due to turbulent velocity fluctuations and sound speed fluctuations. The resonances in the output power spectrum which would occur at the cut-off frequencies in the absence of dissipation should be removed and smeared out by the incorporation of dissipation. Wave number dependence is developed for an effective eddy viscosity due to the aforementioned fluctuations in the background medium. The space-time correlation function for blade-normal velocity fluctuations on a single or on two different blades is developed in terms of the velocity correlation tensor for the inflow under the assumptions of isotropy and (Taylor) frozen behavior. The correlation function is then simplified under certain approximations and the behavior of the blade-force correlation function is inferred.
Influence Of Vane Sweep On Rotor Stator Interaction Noise
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-07-18
Influence Of Vane Sweep On Rotor Stator Interaction Noise written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-18 with categories.
The influence of vane sweep in rotor-stator interaction noise is investigated. In an analytical approach, the interaction of a convected gust representing the rotor viscous wake, with a cascade of cascade of finite span swept airfoils, representing the stator, is analyzed. The analysis is based on the solution of the exact linearized equations of motion. High frequency convected gusts for which noise generation is concentrated near the leading edge of airfoils is considered. In a preliminary study, the problem of an isolated finite span swept airfoil interacting with a convected gust is analyzed. Results indicate that sweep can substantially reduce the farfield noise levels for a single airfoil. Using the single airfoil model, an approximate solution to the problem of noise radiation from a cascade of finite span swept airfoils interacting with a convected gust is derived. A parametric study of noise generated by gust cascade interaction is carried out to assess the effectiveness of vane sweep in reducing rotor-stator interaction noise. The results show that sweep is beneficial in reducing noise levels. Rotor wake twist or circumferential lean substantially influences the effectiveness of vane sweep. The orientation of vane sweep must be chosen to enhance the natural phase lag caused by wake lean, in which case rather small sweep angles substantially reduce the noise levels. Envia, Edmane and Kerschen, Edward J. Unspecified Center GUSTS; NOISE GENERATORS; NOISE REDUCTION; ROTOR STATOR INTERACTIONS; ROTORS; SOUND WAVES; STATORS; SWEEP ANGLE; SWEEP EFFECT; TURBOFAN ENGINES; VANES; WAKES; AIRFOILS; APPROXIMATION; EQUATIONS OF MOTION; HIGH FREQUENCIES; LEADING EDGES; MODELS; NOISE INTENSITY...