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.

本文通过实验研究了操作参数对贫预混燃烧器热声不稳定性的影响。选择燃烧室长度和甲烷流量作为操作参数。实验结果表明，随着燃烧室长度的变化，火焰经历了不同的振荡模式。利用非线性时间序列分析工具，如相空间重构或递推图，可以获得热声不稳定性的动态特性。随着甲烷流速从 2.0 L/min 增加到 4.5 L/min，热声火焰从混沌状态演变为极限循环状态。当燃烧室长度从100 mm增加到800 mm时，存在极端振荡点。最大热声不稳定点出现在 600 毫米处。火焰形状与热声不稳定过程紧密相连，出现了一个中空的内部再循环区域。本文可以促进被动控制方法在防止燃烧不稳定方面的应用。