A method to identify thermoacoustic growth rates in combustion chambers from dynamic pressure time series

The stochastic nature of combustion instabilities in practical land-based gas turbines and aeroengines combustors has seldom been investigated. It is shown here that a wealth of information about the constructive acoustic-flame interactions can be gained by scrutinising the effects of the inherent turbulence-induced noise, which forces the nonlinear thermoacoustic dynamics. In particular, one presents a method, based on the Fokker-Planck formalism, to identify from dynamic pressure signals the linear growth rates, the type of flame response nonlinearity and the potential defining the system acoustic energy. It is applied to and validated against experimental data measured in a lab-scale combustion chamber.