Thermoacoustic Analysis of Combustion Instability Importing RANS Data

G. Campa[1], E. Cosatto[2], S. Camporeale[1]
[1]Politecnico di Bari, Bari, Italy
[2]Ansaldo Energia, Genova, Italy

A hybrid technique based on the use of the FEM and the transfer matrix method is used to identify the frequencies at which thermoacoustic instabilities are expected and the growth rate of the pressure oscillations at the onset of instability. The Helmholtz equation is used to model the combustion chamber and the classical ?-? formulation for the flame model is adopted. The gas turbine combustion chamber by Ansaldo Energia is modeled in COMSOL. Operating conditions are taken from experimental data and from RANS simulations of Ansaldo combustor. File data from RANS simulations are therefore imported into COMSOL.The proposed method is therefore able to establish a theoretical relation of the characteristics of the flame to the onset of the thermoacoustic instability.