Influence of Acoustically Induced Vorticity Perturbations on High-Frequency Thermoacoustic Instabilities in Gas Turbine Combustors

The goal of this work is to provide a reliable and time-efficient computational tool for the prediction of high-frequency thermoacoustic instabilities in lean-premixed gas turbine combustors. A stability analysis strategy is proposed, which unfolds into three steps: #1 assessment of the linear thermoacoustic stability, #2 analysis of limit-cycle oscillations as well as identification of nonlinear saturation effects and #3 consideration of modal interactions between multiple unstable acoustic eigenmodes. Particular focus is put on the correct incorporation of the influence of acoustically induced vorticity disturbances on the thermoacoustic stability behavior to these three analysis steps. This is achieved by the integration of new models as well as by removing numerical errors in stability computations. Fundamental numerical studies together with the application of decomposition methods provide detailed physical insight into the dynamical behavior of high-frequency thermoacoustic systems and support the development process of the stability prediction tool.