Thermoacoustically-Based Combustion Oscillation in a Gas Turbine—A Brief Note

Thermoacoustic combustion oscillation and vibration experienced in a gas turbine at operation is reported. The oscillation manifested itself at two distinct frequencies representing the first and second mode frequencies of the combined hot and cold (combustion chamber/burner air) Rijke type thermoacoustic model. The first mode was a lower amplitude thermoacoustically driven free Rijke mode. The higher frequency second Rijke mode coupled with the second acoustic mode of the combustion chamber resulted in high amplitude oscillation. Modifications to the burner cold air components are considered which would eliminate the oscillation. The paper will present and discuss the principal parameters which caused the oscillation and changes which would eliminate it.