Dynamic behavior and driving region of thermoacoustic combustion oscillations in a swirl-stabilized turbulent combustor

Abstract

We attempt to identify the driving region of combustion oscillations by methodologies based on symbolic dynamics, synchronization, and complex networks. As the equivalence ratio is increased, the dynamic behavior of pressure fluctuations transitions from a stable combustion state to high-amplitude combustion oscillations via type-II intermittent combustion oscillations and the subsequent low-amplitude combustion oscillations. Rayleigh index-based transition network entropy is a useful indicator for determining the driving region of low-amplitude combustion oscillations. We clearly observe that a critical slowing down begins to appear in the combustion state close to the formation region of type-II intermittent combustion oscillations with temporally increasing equivalence ratio.