Use of Dynamic Meshes for Transient Metal Temperature Prediction

This paper describes the thermal analysis conducted on a three-dimensional model of a stator well contained within a turbine assembly. A methodology has been developed for coupled fluid-solid modelling accounting for the boundary deflections predicted by the structural analysis. The coupling is obtained through an iterative process between a finite element code (FEA) performing structural and thermal analysis for the solid part, and a finite volume solver for the CFD. As the engine runs transiently through a specified flight cycle, the FEA predictions of metal deformations and temperatures are passed to the CFD code, which in turns computes the heat fluxes over the metal surfaces. A robust moving mesh technique is used to automatically modify an initial mesh, based on the cold geometry, to the time dependent boundary deflections. Thus, the methodology guarantees that the CFD is always carried out on the hot-running geometry. A thorough investigation into the flow physics involved in the stator well is conducted. It is shown that an accurate thermal modelling for transient regimes necessitates the correct prediction of the time dependent clearances present in the system. Even small changes in the clearances may cause a transition between different dynamic behaviours, egress or ingestion, ultimately leading to drastically different thermal responses.