In several technical combustion systems for lean, premixed combustion, mixture stratification plays an important role, such as in stationary and aero gas turbines. The current paper focuses on a detailed characterization of a dual-swirl gas turbine model combustor operated in a stratified regime. The influence of mixture stratification on flame stabilization and self-induced thermo-acoustic oscillations was studied using laser and optical diagnostics in combination with microphone probes to measure pressure oscillations in the plenums and combustion chamber. The overall flame-shape was imaged using OH * chemiluminescence. Laser Raman scattering was applied to study the thermo-chemical state of the flame, the flow-field was measured using Particle Image Velocimetry and pressure oscillations in the combustion chamber and in the air plenums were determined by using calibrated microphone probes. OH planar laser-induced fluorescence was used to determine fluctuations of the hot gas with high spatial resolution. Significant mixture stratification within the combustion chamber was found to only occur at or upstream of the flame root. Varying the stratification level did not significantly influence the mean flame shape and flow field, however, a clear influence on thermo-acoustic oscillations was observed.

中文翻译：

---

燃料分级对预混分层双涡流燃气轮机模型燃烧器中热声振荡的影响

在一些用于稀薄预混燃烧的技术燃烧系统中，混合物分层起着重要作用，例如在固定式燃气轮机和航空燃气轮机中。当前论文重点介绍了在分层状态下运行的双涡流燃气轮机模型燃烧器的详细特征。使用激光和光学诊断结合麦克风探头来测量增压室和燃烧室中的压力振荡，研究了混合物分层对火焰稳定和自感应热声振荡的影响。整体火焰形状使用 OH * 化学发光成像。应用激光拉曼散射来研究火焰的热化学状态，流场是使用粒子图像测速法测量的，燃烧室和空气室中的压力振荡是通过使用校准的麦克风探头确定的。OH 平面激光诱导荧光用于以高空间分辨率确定热气体的波动。发现燃烧室内的显着混合物分层仅发生在火焰根部处或上游。改变分层水平没有显着影响平均火焰形状和流场，但是，观察到对热声振荡的明显影响。发现燃烧室内的显着混合物分层仅发生在火焰根部处或上游。改变分层水平没有显着影响平均火焰形状和流场，但是，观察到对热声振荡的明显影响。发现燃烧室内的显着混合物分层仅发生在火焰根部处或上游。改变分层水平没有显着影响平均火焰形状和流场，但是，观察到对热声振荡的明显影响。