Life Estimation of TBC on an Aero Gas Turbine Combustor: A Finite Element Approach

Abstract

Thermal barrier coatings (TBCs) are used for the thermal protection of turbine engine hot end components to have increased life and or better performance. Due to extreme environments and cyclic loads experienced by these components, the TBC may also fail prematurely. Once the TBC fails, it exposes the underlying substrate to very high gas temperatures and the life of the component gets reduced drastically and it can fail within its prescribed service life. This has necessitated the accurate possible estimation of TBC life. The TBC coated transition liner of an aero engine reverse flow combustion chamber has been analysed using finite element approach for life estimation. Stress analysis followed by fatigue analysis is carried out based on a typical mission cycle of the component for life estimation. The approach focuses on the mismatch in thermo-physical properties, operational conditions, Thermally Grown Oxide (TGO) layer surface finish and its growth. Increase in TGO thickness leads to decrease in life — this fact is modelled appropriately and proved using this FEM based methodology. Actual failure data of service engines has also been analysed and compared with that of predicted. This approach can be extended for parametric studies and life evaluation of any TBC system. The present approach will be adopted for qualification of prime reliant TBC for Aero engine application.