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Aeroacoustic control of landing gear noise using perforated fairings

Aeroacoustic control of landing gear noise using perforated fairings
Aeroacoustic control of landing gear noise using perforated fairings
A study was performed to investigate and optimize the application of perforated fairings for landing gear noise control. The sparse knowledge about this new subject has necessitated a more fundamental study involving a basic fairing-strut configuration, followed by wind tunnel tests on a simplified landing gear configuration incorporating perforated fairings. For the basic configuration, various exchangeable perforated half-cylindrical shells shrouding a circular cylinder were the subject of aerodynamic and acoustic tests. A qualitative and quantitative description has been given of the influence of perforated fairings on time averaged and unsteady flow and the related acoustics. The bled air through the shell prevents the formation of large scale vortices associatedwith the shell and thereby reduces low frequency noise. However, a test with a noisy H-beam replacing the circular cylinder has indicated that increasing porosity can result in adverse noise effects due to the bled mass flow washing the strut. Shearing flow past the perforate has been shown to create adverse self-noise of which both intensity and spectral content are dictated by the local velocity past the perforate. The application of perforated fairings to the simplified landing gear model reduces the low frequency noise introduced by the solid fairings to values below the baseline landing gear configuration in both side and ground view directions. Exposing the perforate outside the stagnation area does not yield extra noise reduction but introduces perforate self-noise. The synthesis of the conducted studies has shed new light on the application of perforated fairings for landing gear noise control. In particular the effects of porosity and perforation location have been clarified. However more research is needed for further optimization of these parameters.
Boorsma, Koen
6a081d2c-d049-4daf-a5a5-57e7c135c273
Boorsma, Koen
6a081d2c-d049-4daf-a5a5-57e7c135c273
Zhang, Xin
3056a795-80f7-4bbd-9c75-ecbc93085421

Boorsma, Koen (2008) Aeroacoustic control of landing gear noise using perforated fairings. University of Southampton, School of Engineering Sciences, Doctoral Thesis, 171pp.

Record type: Thesis (Doctoral)

Abstract

A study was performed to investigate and optimize the application of perforated fairings for landing gear noise control. The sparse knowledge about this new subject has necessitated a more fundamental study involving a basic fairing-strut configuration, followed by wind tunnel tests on a simplified landing gear configuration incorporating perforated fairings. For the basic configuration, various exchangeable perforated half-cylindrical shells shrouding a circular cylinder were the subject of aerodynamic and acoustic tests. A qualitative and quantitative description has been given of the influence of perforated fairings on time averaged and unsteady flow and the related acoustics. The bled air through the shell prevents the formation of large scale vortices associatedwith the shell and thereby reduces low frequency noise. However, a test with a noisy H-beam replacing the circular cylinder has indicated that increasing porosity can result in adverse noise effects due to the bled mass flow washing the strut. Shearing flow past the perforate has been shown to create adverse self-noise of which both intensity and spectral content are dictated by the local velocity past the perforate. The application of perforated fairings to the simplified landing gear model reduces the low frequency noise introduced by the solid fairings to values below the baseline landing gear configuration in both side and ground view directions. Exposing the perforate outside the stagnation area does not yield extra noise reduction but introduces perforate self-noise. The synthesis of the conducted studies has shed new light on the application of perforated fairings for landing gear noise control. In particular the effects of porosity and perforation location have been clarified. However more research is needed for further optimization of these parameters.

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Published date: June 2008
Organisations: University of Southampton

Identifiers

Local EPrints ID: 66081
URI: https://eprints.soton.ac.uk/id/eprint/66081
PURE UUID: e37d2946-75e0-49b7-9fb4-ae9a6a8bc0e0

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Date deposited: 28 Apr 2009
Last modified: 24 Jul 2017 16:43

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Contributors

Author: Koen Boorsma
Thesis advisor: Xin Zhang

University divisions

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