Analysis on Combustion Instability Characteristics of Model Swirl Combustor With Gas Fuel

Abstract

Combustion instability is easy to occur under lean combustion of gas turbine. Analyzing and predicting the characteristics of unstable combustion is of great significance to ensure the normal operation of combustion chamber. The flame describing function (FDF) of combustion chamber was obtained by numerical simulation, and the thermoacoustic instability characteristics of combustion chamber were predicted by combining the low-order thermoacoustic network model. Firstly, the operating conditions and main frequency of oscillating combustion were obtained through the self-excited oscillation experiment of model swirler combustor.Secondly, by using large eddy simulation (LES), the response characteristics of heat release rate of flame combustion under different inlet disturbances were obtained, and the FDF was fitted. Finally, the low-order thermoacoustic network model of the combustion chamber was established, and the instability characteristics of the combustion chamber were analyzed. The results show that the oscillation characteristics predicted by the model are consistent with the experimental data, indicating that the model can predict the combustion instability characteristics from the mechanism.

Keywords

• gas turbine combustor
• combustion instability
• thermoacoustic network model
• large eddy simulation (les)
• flame describing function (fdf)