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Effects of Nonlinear Modal Interactions on the Thermoacoustic Stability of Annular Combustors

2018; ASM International; Volume: 141; Issue: 2 Linguagem: Inglês

10.1115/1.4040768

1528-8919

Alessandro Orchini, Georg A. Mensah, Jonas P. Moeck,

Atmospheric chemistry and aerosols

In this theoretical and numerical analysis, a low-order network model is used to investigate a thermoacoustic system with discrete rotational symmetry. Its geometry resembles that of the MICCA combustor (Laboratoire EM2C, CentraleSupelec); the flame describing function (FDF) employed in the analysis is that of a single-burner configuration and is taken from experimental data reported in the literature. We show how most of the dynamical features observed in the MICCA experiment, including the so-called slanted mode, can be predicted within this framework, when the interaction between a longitudinal and an azimuthal thermoacoustic mode is considered. We show how these solutions relate to the symmetries contained in the equations that model the system. We also discuss how considering situations in which two modes are linearly unstable compromises the applicability of stability criteria available in the literature.