A Coupled CFD Framework for Combustor Turbine Interaction in a Research Aeroengine

TL;DR

This paper develops a fully coupled combustor–turbine framework to study CTI under SAF and hydrogen scenarios using a flux-averaged, conservatively exchanging interface between a pressure-based combustor solver with finite-rate chemistry and a density-based turbine solver with tabulated chemistry. A four-dimensional tabulated chemistry approach and a PaSR-like closure ensure thermochemical consistency across the interface, enabling realistic hot-streak transport through turbine blade rows. Demonstrated on the MYTHOS Virtual Test Rig, the coupled simulations reveal that while mean aerodynamic loading is largely unchanged, the turbine experiences pronounced circumferential variations in blade temperature due to nonuniform inlet conditions and clocking effects, establishing a robust foundation for fuel-specific core-engine assessments. The results underscore the importance of fully coupled CTI modeling for accurately predicting aerothermal loads and guide future enhancements such as LES/DES fidelity and cooling-flow integration to support SAF and hydrogen propulsion design.

Abstract

This work presents a fully coupled combustor turbine simulation framework applied to the MYTHOS aeroengine, developed within the Horizon Europe project MYTHOS, aimed at assessing the impact of Sustainable Aviation Fuels (SAFs) and hydrogen on next generation propulsion systems. The numerical setup features a dynamic, bidirectional coupling between a pressure-based solver with detailed finite rate chemistry, deployed in the combustor, and a density-based turbomachinery solver employing tabulated thermochemistry for efficiency, used for the turbine. The coupling is realised through a flux-averaging methodology that ensures conservative exchange of flow quantities and allows flow in arbitrary directions across the interface. Previous validation steps of presented methodology have shown the viability of the approach and are also shortly reviewd. The paper focuses on the chemistry handling strategy that guarantees thermochemical consistency between the two solvers. Coupled reacting simulations at cruise operating conditions demonstrate the capability of the framework to capture combustor generated hot streaks transport and their influence on turbine aerothermal loading. Comparison with segregated simulations of the two components shows that coupling captures the highly unsteady temperature and flow distributions at the turbine inlet and across the blade rows. Whilst mean aerodynamic loading are essentially unchanged, a realistic circumferential variability in blade thermal loading can be observed in the coupled simulations, thus establishing a consistent foundation for future studies on the effects of alternative fuels on core engine components.

Figures (13)

• Figure 1: CAD illustration of combustor and turbine
• Figure 2: Computational cost comparison: species transport vs tabulation
• Figure 3: Mean and std. deviation of mapping error at interface
• Figure 4: Temperature distribution at combustor outlet
• Figure 5: Look up table (Temperature) and tabulation-coordinate samples throughout the turbine domain