Modal cut-on ratio in ducts with realistic flow profiles and its application to acoustic mode detection
Modal cut-on ratio in ducts with realistic flow profiles and its application to acoustic mode detection
This paper considers the modal cut-on ratio and its use in acoustic mode detection in ducts for a radially varying flow with swirl. These concepts have previously only been considered for the idealised case of uniform axial mean flow and no swirl, and thus in this paper they are generalised and extended to account for radial variations in axial and swirl Mach numbers. The cut-on ratio is shown to no longer satisfy a simple relation with the axial wavenumber, showing that while the cut-on ratio in arbitrary flow is defined its usefulness significantly decreases. Mode distribution functions are also investigated for radially varying flows, both in terms of cut-on ratio and axial wavenumber. In view of the deficiencies of the cut-on ratio highlighted in the paper a recent method for mode detection in ducts that uses just two microphones is generalised to deduce the mode amplitudes in radially varying flows, based on modal axial wavenumber rather than cut-on ratio. This method is shown to perform better than the existing method in radially varying and/or swirling flow in simple test configurations with an idealised source distribution.
Cut-on frequency, Cut-on ratio, Mode detection, Two-microphone method
404-421
Mathews, J.R.
ed3e4148-171f-4144-87b8-5bbfe0fc7db3
Chen, J.
bcb18d37-5d26-4250-9491-0f35f5a8b4f2
Joseph, P.
9c30491e-8464-4c9a-8723-2abc62bdf75d
10 November 2018
Mathews, J.R.
ed3e4148-171f-4144-87b8-5bbfe0fc7db3
Chen, J.
bcb18d37-5d26-4250-9491-0f35f5a8b4f2
Joseph, P.
9c30491e-8464-4c9a-8723-2abc62bdf75d
Mathews, J.R., Chen, J. and Joseph, P.
(2018)
Modal cut-on ratio in ducts with realistic flow profiles and its application to acoustic mode detection.
Journal of Sound and Vibration, 434, .
(doi:10.1016/j.jsv.2018.07.003).
Abstract
This paper considers the modal cut-on ratio and its use in acoustic mode detection in ducts for a radially varying flow with swirl. These concepts have previously only been considered for the idealised case of uniform axial mean flow and no swirl, and thus in this paper they are generalised and extended to account for radial variations in axial and swirl Mach numbers. The cut-on ratio is shown to no longer satisfy a simple relation with the axial wavenumber, showing that while the cut-on ratio in arbitrary flow is defined its usefulness significantly decreases. Mode distribution functions are also investigated for radially varying flows, both in terms of cut-on ratio and axial wavenumber. In view of the deficiencies of the cut-on ratio highlighted in the paper a recent method for mode detection in ducts that uses just two microphones is generalised to deduce the mode amplitudes in radially varying flows, based on modal axial wavenumber rather than cut-on ratio. This method is shown to perform better than the existing method in radially varying and/or swirling flow in simple test configurations with an idealised source distribution.
Text
modal-cut-ratio
- Accepted Manuscript
Text
1-s2.0-S0022460X18304413-main
- Version of Record
Restricted to Repository staff only
Request a copy
More information
Accepted/In Press date: 3 July 2018
e-pub ahead of print date: 18 August 2018
Published date: 10 November 2018
Keywords:
Cut-on frequency, Cut-on ratio, Mode detection, Two-microphone method
Identifiers
Local EPrints ID: 425877
URI: http://eprints.soton.ac.uk/id/eprint/425877
ISSN: 0022-460X
PURE UUID: 15c1c9e3-7428-4b53-b4e0-72cb678b2339
Catalogue record
Date deposited: 05 Nov 2018 17:30
Last modified: 18 Mar 2024 05:19
Export record
Altmetrics
Contributors
Author:
J.R. Mathews
Author:
J. Chen
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