The effect of higher order modes on the performance of large diameter dissipative silencers

Publication Type:
Conference Proceeding
Citation:
Proceedings of Forum Acusticum, 2014, 2014-January
Issue Date:
2014-01-01
Full metadata record
Files in This Item:
Filename Description Size
Forum Acusticum Williams Kirby 2014.pdfPublished version327.27 kB
Adobe PDF
Within the gas turbine industry dissipative silencers are regularly used to reduce broadband noise within duct systems. Silencer performance is normally quantified using the insertion loss due to a plane wave incident sound field. However for larger silencers the widths of these duct systems are large enough to allow higher order modes to propagate over much of the frequency range of interest (31-8kHz octave bands), which may have a significant effect upon silencer performance that is not normally accounted for. The performance of dissipative parallel baffle and bar silencers in the presence of different types of incident sound field is investigated through a numerical model which uses the finite element method and point collocation to predict insertion loss. Excitation of the silencer using an equal modal energy density sound field is found to have a large effect upon performance compared to plane wave excitation. Increases to insertion loss are predicted at high frequencies for the geometries modelled and it is found that plane wave predictions do not necessarily give the worst case performance.
Please use this identifier to cite or link to this item: