Abstract: In order to investigate the combustion instability characteristics of staged swirl combustor，dynamic pressure under different fuel air ratio and stage ratio were tested. Results show that when overall combustion equivalence ratio is 0.47~0.68 and the main stage equivalence ratio is 0.48~0.65，the amplitude of pressure pulsation increases with equivalence ratio increase. Relation of flame thickness，flame length，laminar flame speed and flow velocity is derived under the laminar flame model and hypothesis of local flame blow out. The conclusion is that pressure pulsation amplitude ps′ is proportional to laminar flame speed SL0. With the fact that SL0 increases with equivalence ratio under lean combustion，ps′ increases with equivalence ratio increases，thus the experiment result is well explained.

Key words: Equivalence ratio；Staged swirl flame；Combustion instability；Pressure oscillation；Local blow out；Laminar flame speed

摘要： 针对分层旋流燃烧室，实验测量了不同分级比和油气比下的动态压力。结果显示:在总燃烧当量比0.47~0.68，主燃级当量比0.48~0.65范围内，燃烧室内的压力脉动幅值随当量比增大而增大。基于层流火焰模型和局部火焰吹熄假设，公式推导了吹熄前后火焰厚度、火焰长度、层流火焰传播速度、气流速度间的关系，得出燃烧不稳定下的压力脉动幅值ps′与层流火焰传播速度SL0成正比，结合贫油状态下SL0随当量比增大而增大这一事实，得出ps′随当量比增大而增大，从而解释了实验结果。

关键词: 当量比；分层旋流火焰；燃烧不稳定性；压力脉动；局部吹熄；层流火焰传播速度