Session: 04-06 Combustion Dynamics - Modeling II

Submission Number: 177946

Comparative Large Eddy Simulations of Simplified Dual- and Single-Can Models to Investigate Combustion Dynamics and Flashback in a Multi-Can IGT Combustor Operating With H₂ 

In medium-to-large industrial gas turbines (IGTs), comprising primarily of lean-premix swirled type can-annular combustors, combustion dynamics become a critical parameter during engine operation, arising from inherent unsteadiness in the combustion process as well as external oscillatory sources. Experimental characterization methods for predicting these dynamics exist; however, high-pressure tests are expensive and often limited in their ability to capture complex engine-representative phenomenon. Comparisons between single-can experiments and multi-can gas turbine operation have shown notable deviations in acoustic behavior, typically in the low-frequency bands. Bridging this gap conventionally requires full-scale engine testing, which is impractical for fast-paced IGT development, especially at the F- or H-class scale. Analytical predictions derived from 1-D or Finite Element acoustic modelling provide an alternative approach but are constrained by the limited physical fidelity. By contrast, a detailed transient unsteady computational analysis can offer improvement in prediction accuracy at a moderate increase in computational cost, while remaining more practical than experimental testing. This paper focuses on a transient unsteady simulation approach, applied to both single and dual-can configurations.

A further challenge for current and next-generation IGTs is the increased adoption of high-hydrogen fuel blends, which elevate the risk of flame flashback within premixing hardware, potentially leading to operational instability and hardware degradation. Understanding both these phenomena requires high-fidelity simulations capable of resolving transient flame–flow coupling, and pressure driven interactions. Large Eddy Simulations (LES) were performed using standard turbulence and proprietary chemical kinetics models to examine flame dynamics and flashback behavior for high-hydrogen fuel blends. These analyses were conducted on a PSM Flamesheet™ type combustor, using the commercial tool STAR-CCM+, for both single-can and dual-can cases. While the single-can LES analysis provides valuable localized flashback occurrence, it cannot capture cross-can acoustic coupling. Here, the dual-can LES, accounting for proper can-to-can dynamic interaction, offers more representative propensity of flashback and its dependency on the combustion thermoacoustics. Notably, differences between the two configurations become evident around the 50% H₂-CH₄ fuel blend, indicating a shift in the system behavior. This paper explores results from both configurations, comparing the combustion dynamics observations and provides insight into flashback mechanisms, supported by relevant field experience.

Presenting Author: Archit Bapat Power Systems Mfg., LLC

Presenting Author Biography: The author earned a Master’s degree in Aerospace Engineering from Georgia Institute of Technology, specializing in combustion and reacting flow systems. His current role as an Aerothermal Engineer at Power Systems Mfg, focuses on the analysis and development of low-emissions gas turbine systems.

Authors:

Archit Bapat Power Systems Mfg., LLC
Gregory Vogel Power Systems Mfg., LLC
Timothy Dammers Thomassen Energy B.V.
Shashikant Aithal Argonne National Laboratory