Spatiotemporal Dynamics of Spray Combustion Oscillations in a Back-Step Combustor From the Viewpoint of Reservoir Computing
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Combustion oscillations arise as a consequence of the intense feedback loop coupling among fluctuations in pressure, heat release rate, and flow velocity in a confined combustor. The incidence of combustion oscillations can cause undesirable structural damage of combustors for aircraft engines. We clarify the spatiotemporal dynamics of acoustic power source and synchronized state of pressure and heat release rate fluctuations during spray combustion oscillations in a back-step combustor using the advanced analysis based on complex networks and machine learning. We adopt two methods: thermoacoustic power network and reservoir computing, to the simulation results obtained by a large-eddy simulation (LES). The LES code is based on that of the previous study. The averaged node strength of the thermoacoustic power network exhibits periodic oscillations in response to the pressure fluctuations. This indicates that the formation and collapse of acoustic power clusters play an important role in driving the spray combustion oscillations. Additionally, we observe a high predictability of pressure fluctuations by the reservoir computing. This suggests the strong phase synchronized state between pressure and heat release rate fluctuations during spray combustion oscillations.
