Unsteady Half-Annulus Computational Fluid Dynamics Calculations of Thermal Migration Through a Cooled 2.5 Stage High-Pressure Turbine

This paper presents an industrial perspective on the potential use of multiple-airfoil row unsteady computational fluid dynamics (CFD) calculations in high-pressure turbine design cycles. A sliding-mesh unsteady CFD simulation is performed for a high-pressure turbine section of a modern aviation engine at conditions representative of engine take-off. The turbine consists of two stages plus a center-frame strut upstream of the low-pressure turbine. The airfoil counts per row are such that a half-annulus model domain must be simulated for periodicity. The total model domain size is 170 MM computational grid points and the solution requires approximately nine days of clock time on 6288 processing cores of a Cray XE6 supercomputer. Airfoil and endwall cooling flows are modeled via source term additions to the flow. The endwall flowpath cavities and their purge/leakage flows are resolved in the computational meshes to an extent. The time-averaged temperature profile solution is compared with static rake data taken in engine tests. The unsteady solution shows a considerable improvement in agreement with the rake data, compared with a steady-state solution using circumferential mixing planes. Passage-to-passage variations in the gas temperature prediction are present in the 2nd stage, due to nonperiodic alignment between the nozzle vanes and rotor blades. These passage-to-passage differences are quantified and contrasted.