Thermoacoustic interactions in a circumferential network of lean-premixed combustors have a substantial impact on engine-level dynamics in a can-annular gas turbine combustion system. Previous experimental and numerical studies have focused on identifying the formation of large-scale interaction patterns and the modal dynamics of multiple eigenmodes. Since those investigations were primarily concerned with low-frequency interactions between adjacent combustors, there are currently no experimental observations that enable decisive discrimination between low- and high-frequency can-annular combustion instabilities. Here, we use pure hydrogen-air flame ensembles to trigger higher acoustic modes in four-coupled lean-premixed combustors, ultimately to understand the potential influence of self-excited instabilities on the spatiotemporal evolution of a can-annular system. The use of lean-premixed hydrogen-air flames enables measurements of previously unidentified phenomena, particularly in association with the excitation of high acoustic modes up to approximately 1.3 kHz. We demonstrate that self-excited standing azimuthal modes can be excited in the annular cross-talk section, particularly when the phase dynamics of the upstream flame tube sections are defined by alternating anti-phase oscillations. In this case, the temporal evolution of the can-annular system is governed by twofold degeneracy, incorporating an alternating push-pull mode in the longitudinal direction and a standing azimuthal mode in the circumferential direction at the same frequency. Based on experimental observations and Helmholtz simulations, we also show that a mixed state of synchronization and desynchronization can arise simultaneously as a result of symmetry breaking. The coexistence of coherent and incoherent motions is observed to be controlled by interactions between two closely spaced, but slightly misaligned, localized in-phase modes; this observation demonstrates experimentally the existence of a chiral state in can-annular thermoacoustics. The present results, for the first time, reveal a variety of phenomena involved in the response of a can-annular combustion system to higher frequency acoustic perturbations.

稀薄预混燃烧器周向网络中的热声相互作用对套管环形燃气轮机燃烧系统中的发动机级动力学产生重大影响。以前的实验和数值研究侧重于识别大规模相互作用模式的形成和多种本征模式的模态动力学。由于这些研究主要关注相邻燃烧器之间的低频相互作用，因此目前没有实验观察可以对低频和高频环管燃烧不稳定性进行决定性区分。在这里，我们使用纯氢-空气火焰合奏在四耦合稀薄预混燃烧器中触发更高的声学模式，最终了解自激不稳定性对环管系统时空演化的潜在影响。使用稀薄预混氢-空气火焰可以测量以前无法识别的现象，特别是与高达约 1.3 kHz 的高声学模式的激发相关联。我们证明可以在环形串扰部分激发自激立式方位角模式，特别是当上游火焰管部分的相位动力学由交替反相振荡定义时。在这种情况下，can-annular 系统的时间演变受双重简并控制，包括纵向交替推挽模式和周向站立方位模式，频率相同。基于实验观察和亥姆霍兹模拟，我们还表明，由于对称性破坏，同步和去同步的混合状态可以同时出现。观察到相干和非相干运动的共存是由两个相距很近但略微错位的局部同相模式之间的相互作用控制的；这一观察结果通过实验证明了环管热声学中手性状态的存在。目前的结果首次揭示了环形燃烧系统对高频声扰动的响应所涉及的各种现象。观察到相干和非相干运动的共存是由两个相距很近但略微错位的局部同相模式之间的相互作用控制的；这一观察结果通过实验证明了环管热声学中手性状态的存在。目前的结果首次揭示了环形燃烧系统对高频声扰动的响应所涉及的各种现象。观察到相干和非相干运动的共存是由两个相距很近但略微错位的局部同相模式之间的相互作用控制的；这一观察结果通过实验证明了环管热声学中手性状态的存在。目前的结果首次揭示了环形燃烧系统对高频声扰动的响应所涉及的各种现象。