The impact of modeling assumptions on the hot spots convection within a cooled high-pressure turbine stage

To reduce pollutant emissions, modern aeroengines adopt combustors that work with lean premixed flames. These generate significant flow distortions, and due to the compact engine architecture, combustor-turbine interaction becomes a crucial design aspect. From an industrial perspective, achieving design targets while minimizing time to market requires effective and efficient design tools. This study employs a state-of-the-art in-house CFD solver, extensively validated for combustor-turbine interaction, to investigate the aerodynamics of an engine-representative high-pressure turbine (HPT) stage tested in the DLR NG-Turb facility within the European FACTOR project. The test case consists of a 1.5 stage cooled transonic turbine, with distorted inlet conditions coming from a combustor simulator. In detail, steady/unsteady RANS (Reynolds-Averaged Navier-Stokes) simulations were carried out to analyze two clocking positions between the swirling hot spot and nozzle guide vanes (leading-edge clocking, passage clocking). Numerical setups combined Roe's upwind, central difference, and schemes with high-Reynolds Wilcox and Menter SST turbulence models, both in baseline and helicity-corrected formulations. Comparison with experimental data shows that time-accurate simulations improve flow-field predictions downstream of the rotor and that the helicity-based correction can significantly enhance the results. To the best of the author's knowledge, this is the first application of helicity-corrected turbulence models in the context of hot-streak interaction with an aeronautical cooled HPT stage. This work demonstrates that URANS simulations with advanced turbulence closures can effectively estimate the complex aerodynamics of realistic HPT and hot-streaks migration, while ensuring computational requirements that are in line with industrial design practices.