INFLUENCE OF COMBUSTOR UNSTEADINESS ON THE AEROTHERMAL LOAD OF A HIGH-PRESSURE TURBINE STAGE USING SCALE-RESOLVING CFD SIMULATIONS

Abstract

Aerothermal interaction between the combustor and the high-pressure turbine is critical for engine efficiency. Standard steady-state methods fail to capture the highly unsteady flow features at the combustor-turbine interface, leading to uncertainties in thermal load prediction. This study investigates the influence of combustor unsteadiness and scale-resolving simulation methods on the aerodynamic performance and thermal load of an engine-representative high-pressure turbine rotor. Numerical investigations utilize RANS, URANS, and Stress-Blended Eddy Simulations. To prescribe realistic unsteadiness, inlet boundary conditions derived from a combustor Large Eddy Simulation are applied via a one-way unsteady coupling method. Results demonstrate that unsteady inlet conditions substantially impact predicted mixing in the stator. This unsteadiness homogenizes the temperature distribution at the stator outlet, significantly increasing temperatures in the end wall regions. While combustor unsteadiness drives turbulent mixing in the stator, rotor passage flow physics are dominated by the choice of the turbulence model. The scale-resolving approach predicts deeper hot gas penetration into the rim seal cavity compared to URANS. Combined with the altered stator exit traverse, this results in higher thermal loads on the rotor blade suction side, particularly in the critical hub and tip regions. Furthermore, the study highlights the significance of inlet unsteadiness for predicting physically consistent flow fields in scale-resolving simulations. Consequently, high-fidelity, transient methods are shown to be essential for accurately predicting thermal loads, relevant for robust cooling design.