Modeling investigation for thermoacoustic oscillation control

It is well known that self-excited oscillation is becoming a major issue in low emission, premixed combustion system. The mechanism of this phenomenon is the interaction between the unsteady heat release and the acoustic waves. Acoustic waves produce fluctuations in heat release, for instance by perturbing the equivalence ratio or flame shape. These heat fluctuations will in turn generate more acoustic waves and in some situations self-excited oscillations can happen. A kinematic heat release model with time-varying delays is proposed and linearized, both the the fully and imperfectly premixed situations are calculated and compared. A simplified acoustic model is developed and the coupling model between the heat release and acoustic model is established. Comparison is made between the theory and experiment.