The present article reports a numerical analysis of instability coupled by a spinning mode in
an annular combustor. This corresponds to experiments carried out on the MICCA test
facility equipped with 16 matrix burners. Each burner response is represented by means of a
global experimental flame describing function (FDF). A harmonic balance nonlinear stability
analysis is carried out by combining the FDF with a Helmholtz solver to determine the
system dynamics trajectories in a frequency-growth rate plane. The influence of the …

Annular combustors of aero-engines and gas turbine are often affected by thermo-acoustic
combustion instabilities coupled by azimuthal modes. Previous experiments as well as
theoretical and numerical investigations indicate that the coupling modes involved in this
process may be standing or spinning but they provide diverse interpretations of the
occurrence of these two types of oscillations. The present article reports a numerical
analysis of instability coupled by a spinning mode in an annular combustor. This …