A weak-scattering model for tone haystacking caused by sound propagation through an axisymmetric turbulent shear layer
A weak-scattering model for tone haystacking caused by sound propagation through an axisymmetric turbulent shear layer
In aeroacoustics, spectral broadening refers to the scattering of tonal sound fields by turbulent shear layers, whereby the interaction of the sound with turbulent flow results in power lost from the tone and distributed into a broadband field around the tone frequency. Fan and turbine tone spectral broadening is known colloquially as “haystacking”. Spectral broadening causes substantial difficulties in determining the relative importance of various sources of turbofan engine noise, as it scatters sound generated by tonal sources across a wide frequency range. This obscures the importance of some key sources of tone noise by apparently reducing their prominence, the resultant broadband noise being often difficult to attribute. Recently a new analytical solution has been derived to predict weak spectral broadening of a tone radiated through a circular jet. In this paper, validation of the weak scattering model is presented. A key aspect of the modelling is the choice of the two-point turbulent velocity cross-correlation function which is used to provide a statistical description of the turbulence in the shear layer. Results obtained using three different cross-correlation functions are compared. These include cross-correlation functions which have been developed using the theory for homogeneous isotropic turbulence or using the theory for homogeneous axisymmetric turbulence. In particular, a new cross-correlation function for an axisymmetric turbulent shear layer formed by a circular jet, based on the theory for homogeneous axisymmetric turbulence, has been developed. Validation results of weak-scattering calculated using this correlation function show better agreement with measurements when compared to the results calculated using correlation functions based on the theory for three-dimensional homogeneous isotropic turbulence.
McAlpine, Alan
aaf9e771-153d-4100-9e84-de4b14466ed7
Tester, Brian
1bd4a793-131b-4173-93cc-3eca70b2d116
McAlpine, Alan
aaf9e771-153d-4100-9e84-de4b14466ed7
Tester, Brian
1bd4a793-131b-4173-93cc-3eca70b2d116
McAlpine, Alan and Tester, Brian
(2016)
A weak-scattering model for tone haystacking caused by sound propagation through an axisymmetric turbulent shear layer.
22nd AIAA/CEAS Aeroacoustics Conference, Lyon, France.
30 May - 01 Jun 2016.
27 pp
.
(doi:10.2514/6.2016-2702).
Record type:
Conference or Workshop Item
(Paper)
Abstract
In aeroacoustics, spectral broadening refers to the scattering of tonal sound fields by turbulent shear layers, whereby the interaction of the sound with turbulent flow results in power lost from the tone and distributed into a broadband field around the tone frequency. Fan and turbine tone spectral broadening is known colloquially as “haystacking”. Spectral broadening causes substantial difficulties in determining the relative importance of various sources of turbofan engine noise, as it scatters sound generated by tonal sources across a wide frequency range. This obscures the importance of some key sources of tone noise by apparently reducing their prominence, the resultant broadband noise being often difficult to attribute. Recently a new analytical solution has been derived to predict weak spectral broadening of a tone radiated through a circular jet. In this paper, validation of the weak scattering model is presented. A key aspect of the modelling is the choice of the two-point turbulent velocity cross-correlation function which is used to provide a statistical description of the turbulence in the shear layer. Results obtained using three different cross-correlation functions are compared. These include cross-correlation functions which have been developed using the theory for homogeneous isotropic turbulence or using the theory for homogeneous axisymmetric turbulence. In particular, a new cross-correlation function for an axisymmetric turbulent shear layer formed by a circular jet, based on the theory for homogeneous axisymmetric turbulence, has been developed. Validation results of weak-scattering calculated using this correlation function show better agreement with measurements when compared to the results calculated using correlation functions based on the theory for three-dimensional homogeneous isotropic turbulence.
Text
__soton.ac.uk_UDE_PersonalFiles_Users_amca_mydocuments_My Work Stuff_Papers (AMcA)_Turbine noise_Haystacking_Haystacking AIAA 2016_Full paper_Final version_AIAA2016_ToneHaystacking_Final.pdf
- Version of Record
Restricted to Repository staff only
Request a copy
More information
Accepted/In Press date: 2 February 2016
e-pub ahead of print date: 30 May 2016
Venue - Dates:
22nd AIAA/CEAS Aeroacoustics Conference, Lyon, France, 2016-05-30 - 2016-06-01
Organisations:
Acoustics Group
Identifiers
Local EPrints ID: 403986
URI: http://eprints.soton.ac.uk/id/eprint/403986
PURE UUID: 9d0ebaff-8de0-4b5d-a1f7-12538c2bc597
Catalogue record
Date deposited: 19 Dec 2016 14:39
Last modified: 16 Mar 2024 03:02
Export record
Altmetrics
Contributors
Author:
Brian Tester
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
