The Impact of Manufacturing Variations on the Aerothermal Performance of High-Pressure Turbine Blade Shrouds

Abstract

High-pressure turbine blade (HPTB) shrouds suffer manufacturing variations in both platform alignment and inter-platform gap width. Compared to hub endwalls, the aerothermal effects of shroud platform steps and gaps has had little attention, which introduces uncertainty in the sentencing of such manufacturing variations. This article presents a shroud step sentencing correlation developed using a parametric quasi-2D (Q2D) model of a shroud endwall step. The use of a Q2D model follows from the study of a 3D steady Reynolds-averaged Navier–Stokes (RANS) simulation matrix of engine-representative platform steps and gap widths, based on a sample of scanned HPTB castings and finished parts. This study showed that the aftchord shroud step flow is Q2D and resembles canonical step flow with enhanced heat transfer at the reattachment point. The shroud step sentencing correlation is tested on the platform steps in the simulation matrix giving prediction errors below 20% for the majority of cases. Finally, the correlation is tuned using experimental data to mitigate the uncertainty associated with RANS simulations of separated flows.