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Updated: Sep 30, 2025

Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
Coupling-induced instability in a ring of thermoacoustic oscillators
1Department of Mechanical and Process Engineering, CAPS Laboratory, ETH Zürich, Sonneggstrasse 3, Zürich 8092, Switzerland.
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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