A theoretical study of leading-edge devices for active and passive control of wake-airfoil interaction noise

Persistent Link:
http://hdl.handle.net/10150/284280
Title:
A theoretical study of leading-edge devices for active and passive control of wake-airfoil interaction noise
Author:
Reba, Ramona Andris
Issue Date:
2000
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:
A theoretical analysis is developed for control of wake-airfoil interaction noise by the use of actuators on the airfoil surfaces near the leading edge. The objective is to eliminate the sound radiation by canceling the wake-airfoil noise near its source (the leading edge). Actuators are mounted on the upper and lower surfaces of the airfoil and driven out of phase to match the antisymmetric nature of the wake-airfoil noise field. The analysis is based on linearization about a two-dimensional compressible subsonic mean flow past a semi-infinite flat-plate airfoil. Asymptotic solutions are developed for the unsteady boundary-layer flow over surface-mounted actuators which are long compared to the triple-deck scale. The analysis shows that boundary layer effects play a significant role in determining the acoustic field, and that traditional approaches used to account for acoustically thin boundary layers are not always adequate. In addition to the acoustic monopole field associated with the actuator volume flux, acoustic monopole and dipole fields are produced at leading order by deflection of the boundary layer into the oncoming free stream. For a specified actuator size and location (relative to the leading edge), the analysis determines the actuator amplitude and phase which minimizes the total sound radiation. The cancellation is most effective when the directivity pattern for the control field closely matches that for the wake-airfoil noise field. At low Mach numbers, this is achieved by mounting the actuators sufficiently close to the leading edge. At high subsonic Mach numbers, the sound cancellation that can be achieved with a single actuator on each surface is limited by mismatch in the directivity patterns. However, a match in directivity patterns can be recovered in part by using two actuators on each surface. The use of passive treatment in the leading-edge region to locally control wake-airfoil interaction noise is also discussed.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Applied Mechanics.; Engineering, Mechanical.; Physics, Acoustics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Aerospace and Mechanical Engineering
Degree Grantor:
University of Arizona
Advisor:
Kerschen, Edward J.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleA theoretical study of leading-edge devices for active and passive control of wake-airfoil interaction noiseen_US
dc.creatorReba, Ramona Andrisen_US
dc.contributor.authorReba, Ramona Andrisen_US
dc.date.issued2000en_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.abstractA theoretical analysis is developed for control of wake-airfoil interaction noise by the use of actuators on the airfoil surfaces near the leading edge. The objective is to eliminate the sound radiation by canceling the wake-airfoil noise near its source (the leading edge). Actuators are mounted on the upper and lower surfaces of the airfoil and driven out of phase to match the antisymmetric nature of the wake-airfoil noise field. The analysis is based on linearization about a two-dimensional compressible subsonic mean flow past a semi-infinite flat-plate airfoil. Asymptotic solutions are developed for the unsteady boundary-layer flow over surface-mounted actuators which are long compared to the triple-deck scale. The analysis shows that boundary layer effects play a significant role in determining the acoustic field, and that traditional approaches used to account for acoustically thin boundary layers are not always adequate. In addition to the acoustic monopole field associated with the actuator volume flux, acoustic monopole and dipole fields are produced at leading order by deflection of the boundary layer into the oncoming free stream. For a specified actuator size and location (relative to the leading edge), the analysis determines the actuator amplitude and phase which minimizes the total sound radiation. The cancellation is most effective when the directivity pattern for the control field closely matches that for the wake-airfoil noise field. At low Mach numbers, this is achieved by mounting the actuators sufficiently close to the leading edge. At high subsonic Mach numbers, the sound cancellation that can be achieved with a single actuator on each surface is limited by mismatch in the directivity patterns. However, a match in directivity patterns can be recovered in part by using two actuators on each surface. The use of passive treatment in the leading-edge region to locally control wake-airfoil interaction noise is also discussed.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectApplied Mechanics.en_US
dc.subjectEngineering, Mechanical.en_US
dc.subjectPhysics, Acoustics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAerospace and Mechanical Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorKerschen, Edward J.en_US
dc.identifier.proquest9992108en_US
dc.identifier.bibrecord.b41170507en_US
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