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Numerical investigation of landing gear noise

Numerical investigation of landing gear noise
Numerical investigation of landing gear noise
Noise generated by aircraft landing gears is a major contributor to the overall airframe noise of a commercial aircraft during landing approach. Because of the complex geometry of landing gears, the prediction of landing gear noise has been very difficult and currently relies on empirical tools, which have limited reliability and flexibility on the applications of unconventional gear architectures. The aim of this research is to develop an efficient and accurate numerical method to investigate the generation and far field radiation of the landing gear noise. In this thesis a hybrid approach is developed that combines near field flow computations with an integral radiation model to enable the far field signal to be evaluated without the need to directly resolve the propagation of the acoustic waves. The recent advances in the CAA methods are implemented with high-order finite difference compact schemes and a characteristics-based multi-block interface treatment. Aerodynamic noise from a generic two-wheel landing gear model, provided by Airbus LAGOON (landing gear noise database for CAA validation) program, is predicted by using the hybrid approach and compared with the LAGOON database. The unsteady flow field is computed by using a compressible Navier-Stokes solver based on high-order finite difference schemes. The calculated time history of surface data is used in a FW-H solver to predict the far field noise levels. Both aerodynamic and aeroacoustic results are compared with wind tunnel measurements in good agreement. Individual contributions from three components, i.e. wheels, axle and strut of the landing gear model are also investigated to identify the major noise source component. It is found that strong flow-body interaction noise is generated by the flow separated from tire rim impinging on the axle. Based on the same landing gear model, the comparison study using conventional CFD solver FLUENT is performed with a second-order Navier-Stokes finite volume solver to compute the unsteady near field flow and the built-in FW-H solver to calculate the far field sound propagation. The comparison suggests that although conventional CFD method can obtain good timeaveraged aerodynamic results, its ability of predicting sound radiation is limited by the inherent low-order numerical discretizations. The aerodynamic noise from the isolated undercarriage wheel with detailed hub configuration is also investigated using FLUENT. The asymmetric phenomenon in the mean flow is discovered in the wake region of the wheel, which contributes to a positive lift force for the wheel. It is predicted that the isolated wheel radiates relatively strong noise to the sides with several strong tonal noise.
Liu, Wen
403ae519-641f-4008-baef-a061ee28de7c
Liu, Wen
403ae519-641f-4008-baef-a061ee28de7c
Zhang, Xin
21e210aa-51db-40af-a91b-f64bf44ed143

Liu, Wen (2011) Numerical investigation of landing gear noise. University of Southampton, Faculty of Engineering and the Environment, Doctoral Thesis, 183pp.

Record type: Thesis (Doctoral)

Abstract

Noise generated by aircraft landing gears is a major contributor to the overall airframe noise of a commercial aircraft during landing approach. Because of the complex geometry of landing gears, the prediction of landing gear noise has been very difficult and currently relies on empirical tools, which have limited reliability and flexibility on the applications of unconventional gear architectures. The aim of this research is to develop an efficient and accurate numerical method to investigate the generation and far field radiation of the landing gear noise. In this thesis a hybrid approach is developed that combines near field flow computations with an integral radiation model to enable the far field signal to be evaluated without the need to directly resolve the propagation of the acoustic waves. The recent advances in the CAA methods are implemented with high-order finite difference compact schemes and a characteristics-based multi-block interface treatment. Aerodynamic noise from a generic two-wheel landing gear model, provided by Airbus LAGOON (landing gear noise database for CAA validation) program, is predicted by using the hybrid approach and compared with the LAGOON database. The unsteady flow field is computed by using a compressible Navier-Stokes solver based on high-order finite difference schemes. The calculated time history of surface data is used in a FW-H solver to predict the far field noise levels. Both aerodynamic and aeroacoustic results are compared with wind tunnel measurements in good agreement. Individual contributions from three components, i.e. wheels, axle and strut of the landing gear model are also investigated to identify the major noise source component. It is found that strong flow-body interaction noise is generated by the flow separated from tire rim impinging on the axle. Based on the same landing gear model, the comparison study using conventional CFD solver FLUENT is performed with a second-order Navier-Stokes finite volume solver to compute the unsteady near field flow and the built-in FW-H solver to calculate the far field sound propagation. The comparison suggests that although conventional CFD method can obtain good timeaveraged aerodynamic results, its ability of predicting sound radiation is limited by the inherent low-order numerical discretizations. The aerodynamic noise from the isolated undercarriage wheel with detailed hub configuration is also investigated using FLUENT. The asymmetric phenomenon in the mean flow is discovered in the wake region of the wheel, which contributes to a positive lift force for the wheel. It is predicted that the isolated wheel radiates relatively strong noise to the sides with several strong tonal noise.

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More information

Published date: August 2011
Organisations: University of Southampton, Aeronautics, Astronautics & Comp. Eng

Identifiers

Local EPrints ID: 210942
URI: http://eprints.soton.ac.uk/id/eprint/210942
PURE UUID: 9907f457-8f51-4ac0-a26a-e0bc113d6319
ORCID for Xin Zhang: ORCID iD orcid.org/0000-0002-6918-1861

Catalogue record

Date deposited: 21 Mar 2012 16:20
Last modified: 14 Mar 2024 04:50

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Contributors

Author: Wen Liu
Thesis advisor: Xin Zhang ORCID iD

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