Large Eddy Simulation of the Cross-Talk Area Dynamics in a Can-Annular Gas Turbine

Can-annular gas turbines are increasingly susceptible to combustion instabilities as industry trends drive toward leaner operation and sustainable fuels. These instabilities are fundamentally linked to acoustic interactions between neighboring combustor cans through the annular gap (cross-talk area) between the combustor exhaust and turbine first stage. This work validates the capability of Large Eddy Simulation (LES) to predict cross-talk area dynamics and gain additional insight into the underlying mechanisms of cross-talk dynamics. Using a specialized test rig at ETH Zürich developed to replicate industrial gas turbine acoustic characteristics, we systematically investigated how can-to-can interface geometry (rectangular and round), axial position, and vane alignment affect aeroacoustic behavior. Natural and forced response measurements revealed that specific geometrical parameters can align shear layer natural frequencies with engine eigen-frequencies, potentially triggering aeroacoustic instabilities (whistling) that couple with combustion tones. The computational study was performed using Cadence’s code Fidelity CharLES, which achieved excellent agreement with experimental data across multiple geometric configurations, accurately capturing both whistling frequencies and spectral content. The study serves two primary purposes: validating the LES approach for future high-fidelity multi-can gas turbine simulations and enhancing understanding of underlying physics to develop and validate low-order models, improving combustion instability predictions in gas turbines.