Combustion oscillation of a self excited combustion-acoustic phenomenon occurs inside the gas turbine combustor. In general, excessive pressure fluctuation of combustion oscillation may impair the gas turbine engine operation and may result in hardware damages. Therefore, combustion oscillation has been one of the problems of the gas turbine development. In this paper, for predicting combustionacoustic instability on the designing stage, we have developed one-dimensional linear instability analysis method and verified the analysis accuracy by premixed combustor laboratory tests. The phase lag between combustion dynamics and acoustic system is considered to affect whether combustion acts to destabilize the whole system. Heat release fluctuation is considered to be influenced from fuel/air ratio fluctuation, which generates at fuel nozzle position and flows to combustion region. Its advection delay time is one of the important parameters in the instability. Further, even if heat source itself is steady, the heat release can fluctuate because gas flow rate fluctuates acoustically, and as results, combustion-acoustic instable can occur. At this mechanism, the flame position and the reaction delay time have important roles. By theoretical discussions and laboratory verifications, we conclude that analysis models of this paper have captured the basic framework needed to predict combustion-acoustic instability.

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Combustion oscillation of a self-excited thermo-acoustic phenomenon occurs inside the gas turbine combustor. Its excessive pressure fluctuation may impair the gas turbine engine operation, and could result in hardware severe damages. Therefore, combustion oscillation is one of the problems of the gas turbine development. In this paper, acoustic liner of an acoustic damping appending device to suppress the combustion oscillation is developed and discussed. Acoustic liner consists of a perforated plate, which the acoustic analysis models have been researched well at other papers referenced in this paper, and back cavity. The accuracy of these acoustic analysis models was verified by the laboratory model tests, and then the effectiveness that acoustic liner can suppress combustion oscillation at high frequencies was verified by the actual engine operation tests. This suppression method can be designed without the detailed combustion prediction. Hence the credible design is relatively easy. As the results of the actual engine operation tests shown in this paper, the gas turbine combustor with acoustic liner can be operating robustly without worrying about high frequency oscillation, and future more contributions to the combustor development can be expected.