Low-emissions can-annular gas turbines are prone to develop low-frequency self-excited thermoacoustic oscillations. Such oscillations arise from the coupling between adjacent combustors and can increase wear and thermal stresses. In this experimental study, we explore the mutual synchronization of two thermoacoustic oscillators (i.e., two model combustors) interacting via dissipative and time-delayed coupling, as introduced via a cross-talk section. Unlike most previous studies, our study makes use of a turbulent lean-premixed flame in each combustor, bringing the system configuration closer to that of practical gas turbines. Using stationary and transient measurements, we examine the effect of the cross-talk diameter and length so as to gain insight into the effect of dissipative and time-delayed coupling. We find that strengthening the dissipative coupling promotes mutual synchronization, but that weakening the dissipative coupling leads to weakly coupled or desynchronized oscillations. On operating the two combustors at different conditions, we find a significant reduction in their overall oscillation amplitude for some coupling conditions. On varying the combustor length and examining the transient response, we find elaborate changes in the pressure-heat-release-rate coupling, spontaneous mode transitions between coupled thermoacoustic modes, and the emergence of a rhomboid structure in the phase plane owing to the coexistence of in-phase and out-of-phase synchronization. In the combustion community, these two types of synchronization are known to be associated with push-push modes and push-pull modes. These findings offer new insight into the mutual synchronization of low-frequency, self-excited thermoacoustic oscillations in can-annular gas turbines, paving the way for the development of improved control strategies.

中文翻译：

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两个火焰驱动的热声振荡器的相互同步：耗散和延时耦合效应。

低排放罐状环形燃气轮机易于产生低频自激热声振荡。这种振荡是由相邻燃烧器之间的耦合引起的，并且会增加磨损和热应力。在本实验研究中，我们探讨了两个热声振荡器（即，两个模型燃烧器）通过耗散和延时耦合相互作用的相互同步，如串扰部分所述。与大多数以前的研究不同，我们的研究在每个燃烧器中使用湍流的稀薄预混火焰，使系统配置更接近于实际燃气轮机。使用静态和瞬态测量，我们检查了串扰直径和长度的影响，以便深入了解耗散和延时耦合的影响。我们发现，加强耗散耦合会促进相互同步，但是减弱耗散耦合会导致弱耦合或去同步振荡。在不同条件下操作两个燃烧器时，我们发现在某些耦合条件下，它们的整体振荡幅度将大大降低。通过改变燃烧室的长度并检查瞬态响应，我们发现压力-热-释放-速率耦合，耦合的热声模式之间的自发模式转变以及相平面中菱形结构的出现会产生复杂的变化。同相和异相同步。在燃烧界中，已知这两种类型的同步与推-推模式和推-推模式相关联。