This work predicts the evolution of self-excited thermo-acoustic instabilities in a gas turbine model combustor using large eddy simulation. The applied flow solver is fully compressible and comprises a transported sub-grid probability density function approach in conjunction with the Eulerian stochastic fields method. An unstable operating condition in the PRECCINSTA test case—known to exhibit strong flame oscillations driven by thermo-acoustic instabilities—is the chosen target configuration. Good results are obtained in a comparison of time-averaged flow statistics against available measurement data. The flame’s self-excited oscillatory behaviour is successfully captured without any external forcing. Power spectral density analysis of the oscillation reveals a dominant thermo-acoustic mode at a frequency of 300 Hz; providing remarkable agreement with previous experimental observations. Moreover, the predicted limit-cycle amplitude is found to closely match its respective measured value obtained from experiments with rigid metal combustion chamber side walls. Finally, a phase-resolved study of the oscillation cycle is carried out leading to a detailed description of the physical mechanisms that sustain the closed feedback loop.

中文翻译：

---

使用可压缩 LES-pdf 方法研究 PRECCINSTA 燃烧器中的热声不稳定性

这项工作使用大涡模拟预测了燃气轮机模型燃烧器中自激热声不稳定性的演变。所应用的流求解器是完全可压缩的，并且包括传输子网格概率密度函数方法和欧拉随机场方法。PRECCINSTA 测试案例中的不稳定操作条件——已知表现出由热声不稳定性驱动的强烈火焰振荡——是所选的目标配置。将时间平均流量统计数据与可用测量数据进行比较，可以获得良好的结果。火焰的自激振荡行为在没有任何外力的情况下被成功捕获。振荡的功率谱密度分析揭示了频率为 300 Hz 时的主要热声模式；与先前的实验观察结果非常一致。此外，发现预测的极限循环幅度与其从刚性金属燃烧室侧壁的实验中获得的相应测量值密切匹配。最后，对振荡周期进行了相位解析研究，从而对维持闭合反馈回路的物理机制进行了详细描述。