This paper studies the effect of internozzle spacing on the lean blow-off of a linear combustor array. The combustor’s lean operability limit did not have a monotonic relationship with internozzle spacing; the configuration with the intermediate nozzle spacing was the most stable. Simultaneous multi-kHz repetition-rate OH planar laser–induced fluorescence (OH-PLIF) and stereoscopic particle image velocimetry (S-PIV) measurements were used to examine the fluid and flame kinematics during the transient blow-off process. Although the blow-off process of any individual nozzle—wherein local extinction led to mixing of cold fluid into the central recirculation zone (CRZ), leading to further extinction—was similar regardless of the internozzle spacing, the presence of adjacent flames influenced both the global and local kinematics. Cross-nozzle flame transport through convection of burning fluid was found to help stabilize the flames in the multinozzle configurations, but could not explain the improved stability of the intermediate spacing case. Furthermore, the intermediate spacing configuration was able to sustain attached flames with greater fluid dynamic strain rate than the other configurations, indicating that it was more resistant to local extinction, ultimately leading to total blow-off. The configuration with the intermediate nozzle spacing had the largest CRZ. A Damköhler number based on the CRZ axial length and bulk velocity at blow-off was relatively constant across the configurations, indicating that a large CRZ provides robustness against the blow-off process. These results demonstrate the complex interplay between fluid dynamics, geometry, and stability of combustion systems.

本文研究了喷嘴间距对线性燃烧器阵列稀薄吹气的影响。燃烧室的稀薄可操作性极限与喷嘴间距没有单调关系。具有中间喷嘴间距的配置是最稳定的。同时使用多kHz重复频率OH平面激光诱导的荧光（OH-PLIF）和立体粒子图像测速（S-PIV）测量来检查瞬态吹扫过程中的流体和火焰运动学。尽管任何单个喷嘴的吹扫过程（局部熄灭导致冷流体混入中央再循环区（CRZ），导致进一步熄灭）都是相似的，而不管喷嘴间的间距如何，但相邻火焰的存在影响了两个全球和本地运动学。发现通过燃烧流体的对流进行的跨喷嘴火焰传输有助于在多喷嘴结构中稳定火焰，但不能解释中间间隔情况的改进稳定性。此外，中间间隔构型能够以比其他构型更大的流体动态应变率来维持附着的火焰，这表明它对局部熄灭更具抵抗力，最终导致了整体吹灭。具有中间喷嘴间距的配置具有最大的CRZ。基于CRZ轴向长度和放气时整体速度的Damköhler数在整个配置中相对恒定，这表明较大的CRZ可以抵抗放气过程。这些结果证明了流体动力学，几何形状，