以多喷嘴阵列燃烧器为对象，研究了甲烷预混模式下不同当量比燃烧的自激热声振荡特性，实验过程中同步测量了热释放率和压力脉动信号并获取了OH*时序图像。利用相空间重构和本征正交分解分别解析了压力脉动、反应区相干结构和各阶模态能量占比。研究结果表明，在当量比0.62~0.85范围内，随着当量比增加，燃烧室内依次出现低频振荡、稳定燃烧、间歇振荡和极限环振荡4种典型燃烧状态；当发生极限环振荡时，压力重构曲线为极限环，其轴线附近没有数据点分布，前3阶能量占比达到70%以上，反应区沿轴向发生明显的交替变化，沿径向具有较好的对称性和均匀性；稳定燃烧时，重构曲线凝成一团，前20阶能量占比不足25%，不存在明显的主频，瞬态火焰形态具有较好的一致性；甲烷预混多喷嘴阵列燃烧器的自激振荡模态为单一轴向振荡模态，和传统旋流燃烧有很大的不同，这可为后续进一步开展多喷嘴阵列燃烧器热声产生机理和抑制方案的研究提供参考。

The selfexcited thermoacoustic oscillation characteristics of the methane premixed multinozzle array combustor were experimentally studied at different equivalent ratios. OH* time sequence images were obtained during the experiment while simultaneously measuring the heat release rate and pressure fluctuation signals. Pressure fluctuations, coherent structures in the reaction zone, and energy ratios of eachorder mode were analyzed by phase space reconstruction and proper orthogonal decomposition, respectively. The research results show that four typical combustion states successively appear with the increase of equivalent ratio in the range of 0.62 to 0.85: low frequency oscillation, steady combustion, intermittent oscillation and limit cycle oscillation; when limit cycle oscillation occurs, the reconstructed curve presents a hollow barrel shape, no data point distributes around axis, and the proportion of the first three orders of energy reaches more than 70%. The flame′s axial path clearly displays alternating changes between light and dark, whereas the radial direction displays good symmetry and regularity; however, under the stable combustion state, the reconstructed curve is agglomerated and disorderly, the first 20 orders of energy accounts for less than 25%, the dominant frequency is not observed, and the transient flame profile has good consistency within a cycle; moreover, the methane premixed multinozzle array burner′s self excited oscillation mode is a single axial oscillation mode, which differs greatly from typical swirl combustion and can serve as a reference for future work on the multinozzle array burner′s thermoacoustic mechanism and suppression strategy.

TK471

国家重大科技专项（J2019-Ⅲ-0020-0064）