Effects of operating parameters on the combustion oscillation behaviour in a lean premixed CH4 combustor

Abstract

This article experimentally studies the influence of operating parameters on thermoacoustic instability in a lean premixed combustor. The combustion chamber length and methane flow rate were selected as the operating parameter. Experimental results show that the flame experienced different oscillation modes as the combustion chamber length varies. With the nonlinear time-series analyzing tools, such as phase space reconstruction or recurrence plot, the dynamic characteristics of thermoacoustic instability can be acquired. As the methane flow rate increased from 2.0 L/min to 4.5 L/min, the thermoacoustically flame evolves from a chaotic state to a limit cycle state. There exists extreme oscillation point as the combustion chamber length increased from 100 mm to 800 mm. The maximum thermoacoustic instability point occurred at 600 mm. The flame shape is tightly connected with the thermoacoustic instability process, and a hollow inner recirculation region emerged. This article can promote the application of passive control methods in the prevention of combustion instability.

Seeds of phase transition to thermoacoustic instability

“…However, in our study, we rely on relative changes in the variance of fluctuations, which are independent of the absolute values of the measurements, but depend rather on the change in the strength of fluctuations of heat release rate. A similar approach has been utilized in recent years to investigate the dynamics of the flame near the transition (Balusamy et al 2015, Kheirkhah et al 2017, Jegal et al 2019, Tao and Zhou 2021.…”