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黎开管中燃烧振荡现象的实验研究发现,在不稳定发生的极限工况附近可能存在幅值周期性变化的振荡现象,也即拍振,其拍频可低于l Hz。本文比较了铁丝网和穿孔陶瓷两种稳焰体对拍振发生的影响;通过时频分析揭示了拍振的声压脉动的主频随时间周期性变化的特征。采用基于数字信号处理器的控制系统,研究了对极限环和拍振的主动控制效果,实验结果表明,黎开管系统中导致拍振的非线性可能使得采用常规主动控制方法难以取得满意的控制效果。
The experimental study of the combustion oscillation in the Li Kai tube shows that there may be periodic oscillations of amplitude in the vicinity of the unstable operating conditions, that is, beat beat, which may be below 1 Hz. In this paper, we compare the effects of two stabilized flame bodies, such as barbed wire mesh and perforated ceramic, on the beat beat. The time-frequency analysis shows that the dominant frequency of the beat pulse changes periodically with time. The control system based on digital signal processor is used to study the active control of limit cycle and beat-beat. The experimental results show that the non-linearity of the beat-open system in the Li-kai system may make it difficult to obtain the satisfactory control by using the conventional active control method effect.