Trailing edge noise produced by the scattering of boundary layer turbulence

Persistent Link:
http://hdl.handle.net/10150/280089
Title:
Trailing edge noise produced by the scattering of boundary layer turbulence
Author:
Schuster, William
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Noise generated at the trailing edges of airfoils can be an important contributor to the sound levels of aircraft and turbomachinery. Previous work on trailing edge noise has largely neglected the role of the mean boundary-layer profile in the sound generation process. In the present work, a trailing edge scattering problem is formulated using a piecewise-linear symmetric mean flow with a non-zero slip velocity at the centerline, providing a representation that is intermediate between the boundary layer and wake flows. The airfoil is modeled as a zero-thickness, semi-infinite flat plate, appropriate for noise generation by sharp trailing edges in the presence of a high Reynolds number flow. The mean boundary-layer profile adjacent to the airfoil surface supports naturally-occurring vortical disturbances that have a non-trivial pressure field and convect at speeds between the slip and free stream velocities. Using these pressure disturbances to represent the turbulent field that is incident on the trailing edge, a mixed boundary value problem is formulated and solved using the Wiener-Hopf technique. This scattering problem is solved for both low Mach number and O(1) Mach number flows. The results show that the presence of the mean flow profile can significantly increase the amplitude of the sound radiated to the far field. In the O(1) Mach number case, the directivity of the scattered field is also appreciably altered. The results of the scattering problem are used along with a simplified model of the wall pressure wavenumber-frequency spectrum to generate a prediction for the power spectrum of the scattered sound field.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Mathematics.; Physics, Acoustics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Applied Mathematics
Degree Grantor:
University of Arizona
Advisor:
Kerschen, Edward J.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleTrailing edge noise produced by the scattering of boundary layer turbulenceen_US
dc.creatorSchuster, Williamen_US
dc.contributor.authorSchuster, Williamen_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractNoise generated at the trailing edges of airfoils can be an important contributor to the sound levels of aircraft and turbomachinery. Previous work on trailing edge noise has largely neglected the role of the mean boundary-layer profile in the sound generation process. In the present work, a trailing edge scattering problem is formulated using a piecewise-linear symmetric mean flow with a non-zero slip velocity at the centerline, providing a representation that is intermediate between the boundary layer and wake flows. The airfoil is modeled as a zero-thickness, semi-infinite flat plate, appropriate for noise generation by sharp trailing edges in the presence of a high Reynolds number flow. The mean boundary-layer profile adjacent to the airfoil surface supports naturally-occurring vortical disturbances that have a non-trivial pressure field and convect at speeds between the slip and free stream velocities. Using these pressure disturbances to represent the turbulent field that is incident on the trailing edge, a mixed boundary value problem is formulated and solved using the Wiener-Hopf technique. This scattering problem is solved for both low Mach number and O(1) Mach number flows. The results show that the presence of the mean flow profile can significantly increase the amplitude of the sound radiated to the far field. In the O(1) Mach number case, the directivity of the scattered field is also appreciably altered. The results of the scattering problem are used along with a simplified model of the wall pressure wavenumber-frequency spectrum to generate a prediction for the power spectrum of the scattered sound field.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectMathematics.en_US
dc.subjectPhysics, Acoustics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineApplied Mathematicsen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorKerschen, Edward J.en_US
dc.identifier.proquest3060959en_US
dc.identifier.bibrecord.b4303827xen_US
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