Unsteady, Half-Annulus CFD Calculations of Thermal Migration Through a Cooled, 2.5 Stage High-Pressure Turbine

Abstract

This paper presents an industrial perspective on the potential use of multiple-airfoil row, unsteady 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 170MM computational grid points, and the solution requires approximately 9 days of clock time on 6,288 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 gas temperature prediction are present in the 2nd stage, due to non-periodic alignment between the nozzle vanes and rotor blades. These passage-to-passage differences are quantified and contrasted.