Session: 35-02 Component/Duct Interaction

Paper Number: 154019

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

Combustion instabilities in can-annular gas turbines involve acoustic interactions between two neighboring cans. These interactions occur through the annular gap, also called cross-talk area, between the combustor exhaust and the turbine first stage. This work aims at gaining insight in the cross-talk area dynamics and its acoustic coupling with combustion tones.

A non-reactive experimental campaign was conducted at ETH Zurich using a test rig designed to reproduce the acoustic characteristics of gas turbine cross-talk areas. The study examined the effects of can-to-can interface geometry (rectangular and round), axial position, and vane position (aligned or misaligned) on the cross-talk area's acoustic behavior. Natural and forced responses of the shear layer were measured from the experiment, revealing that specific geometrical parameters can align the shear layer's natural frequency with engine eigenfrequencies, potentially triggering aeroacoustic instabilities (whistling) that couple with combustion tones.

The present research demonstrates the capability of large-eddy simulations (LES) to accurately capture whistling frequencies and extract cross-talk area impedance. The code CharLES (a cell-centered finite volume, compressible, wall-modeled LES solver) was used to perform the simulations for various splitting plate geometries, axial positions, and vane positions, showing excellent agreement with experimental data. The study reproduced key experimental configurations, including the square and round geometry in misaligned and aligned configurations for both natural and forced responses.

To ensure accurate acoustic behavior, the experiment inlet acoustic reflection coefficient behavior was matched in the simulations using a dissipative sponge layer extension of the geometry. Mesh sensitivity studies were also conducted to efficiently capture the necessary aeroacoustic sources in the flow field, resulting in LES results that closely aligns with experimental measurements. The acoustic impedance of the cross-talk area was also extracted from the forced response simulations using a numerically optimized broadband forcing signal and transient boundary conditions within the compressible LES solver. Results compare favorably to experimental data, validating the numerical approach.

This comprehensive study serves two primary purposes: Firstly, it allows for the tuning and validation of the LES approach for future high-fidelity multi-can gas turbine simulations; and secondly, it enhances our understanding of the underlying physics to develop and validate low-order models, improving combustion instability predictions in gas turbines. By providing high-fidelity numerical data that closely matches experimental results, this work establishes a foundation for improved modeling and prediction of complex acoustic phenomena in gas turbine combustors. The validated LES methodology offers a powerful tool for future investigations into can-annular combustor dynamics and stability optimization.

Presenting Author: Christopher Bogaev GE Vernova

Presenting Author Biography: The presenting author is a lead combustion dynamics engineer at GE Vernova, specializing in the use of large eddy simulation (LES) for the prediction and analysis of thermoacoustic instabilities in gas turbine combustors. He earned his Bachelor's degree in Mechanical Engineering from Texas A&M University, establishing a strong foundation in thermal sciences, fluid dynamics, and numerical methods. He then pursued a Master's degree in Mechanical Engineering at Georgia Institute of Technology, where he focused on experimental thermoacoustics, combustion dynamics, and flame transfer function measurement under the guidance of Dr. Tim C. Lieuwen. His academic background, combined with his current industrial experience at GE Vernova, uniquely positions him to bridge the gap between advanced numerical simulations, fundamental research, and practical applications in the field of combustion dynamics.

Authors:

Christopher Bogaev GE Vernova
Layal Hakim GE Vernova
Sven Bethke GE Vernova
Audrey Blondé ETH Zürich
Bruno Schuermans ETH Zürich
Nicolas Noiray ETH Zürich