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本文实验观测到一种微型燃气轮机的DLN燃烧室工作在预混模式时存在低频燃烧振荡现象,其振荡频率为1～2 Hz。采用数值模拟方法探讨了该低频振荡的形成原因。燃烧室流场的数值模拟结果再现了该低频振荡现象,结果表明,产生该低频振荡的原因为进入燃烧室之前的腔体内存在周期性回流,诱发了该低频振荡。通过修改结构,可有效消除该低频振荡,这进一步印证了该低频振荡产生的原因。本文实验观测到的低频燃烧振荡现象在以往文献中未见报道,本文工作对于理解燃烧振荡的成因及DLN燃烧室的设计有重要意义。
In this paper, it is observed that the DLN combustion chamber of a micro-gas turbine has a low-frequency combustion oscillation phenomenon in the premixed mode, and its oscillation frequency is 1~2 Hz. The reason of the low frequency oscillation is discussed by numerical simulation. The results of numerical simulations of the flow field in the combustion chamber reproduce the low-frequency oscillation. The results show that the low-frequency oscillation is caused by the periodic backflow in the cavity before entering the combustion chamber, which causes the low-frequency oscillation. By modifying the structure, the low-frequency oscillation can be effectively eliminated, further confirming the reason for the low-frequency oscillation. The phenomenon of low-frequency combustion oscillations observed in this paper has not been reported in the past literature. The work in this paper is of great significance for understanding the causes of combustion oscillation and the design of DLN combustion chamber.