Coupling-induced instability in a ring of thermoacoustic oscillators
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2022-03-30
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Journal Article
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yes
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Abstract
Thermoacoustic instabilities in can-annular combus-tors of stationary gas turbines lead to unstable Bloch modes which appear as rotating acoustic pressure waves along the turbine annulus. The multiscale, multiphysical nature of the full problem makes a detailed analysis challenging. In this work, we derive a low-order, coupled oscillators model of an idealized can-annular combustor. The unimodal projection of the Helmholtz equation for the can acoustics is combined with the Rayleigh conductivity, which describes the aeroacoustic coupling between neighbouring cans. Using a Bloch-wave ansatz, the resulting system is reduced to a single equation for the frequency spectrum. A linear stability analysis is then performed to study the perturbation of the spectrum by the can-to-can interaction. It is observed that the acoustic coupling can suppress or amplify thermoacoustic instabilities, raising the potential for instabilities in nominally stable systems.
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published
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478 (2259)
Pages / Article No.
20210851
Publisher
Royal Society
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09471 - Noiray, Nicolas / Noiray, Nicolas
00012 - Lehre und Forschung
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184617 - Thermoakustische Instabilitäten in Rohr-Ringbrennkammern (SNF)
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Is part of: https://doi.org/10.3929/ethz-b-000664067