Prediction of the resonance characteristics of combustion chambers on the basis of large-eddy simulation

Abstract

Self-excited (thermo-acoustic) oscillations often occur in combustion systems due to the combustion instabilities. The high pressure oscillations can lead to higher emissions and structural damage of the chamber. For the disposal of the undesirable oscillations one must clearly know the mechanism of the feedback of periodic perturbations in the combustion system. In the last years intensive experimental investigations were performed at the University of Karlsruhe to develop an analytical model for the Helmholtz resonator-type combustion system. In order to understand better the flow effects in the chamber and to localize the dissipation large-eddy simulations (LES) were carried out. In this paper the results of the LES are presented, which show good agreement with the experiments. The comparison of the LES study with the experiments sheds light on the significant role of the wall roughness in the exhaust gas pipe.