Study on the Residual Stress in Film-Cooled Turbine Blade-Thermal Barrier Coating System with 3D Finite Element Model

Abstract

In this study, a three-dimensional finite element model was developed with an air-film cooled turbine blade as a substrate on which a thermal barrier coating (TBC) was sprayed, considering the interface morphology of the TBC system. By means of a simulation study method, the residual stresses at the interface of the TBC are calculated when the temperature of the TBC decreases linearly from 1000 to 25 °C, the influence of air-film cooling holes geometry parameters on residual stress in TBC system was studied. In the study, it was found that the shape and positional characteristics of the air-film cooling holes, such as the position of the cooling hole, radius, ratio between upper and lower radii of a cooling hole, and space angle, have certain effect on the residual stress. When the air-film cooling holes are located at the lowest part of the TBC interface, there is minimal residual stress, while at the junction of the bond coat and the thermally grown oxide, there is a more severe stress concentration, which should be paid special attention to. The radius of air-film cooling holes not only affects the value of the residual stress but also affects the range of its extreme value, and the small radius of cooling hole can reduce the residual stress to a large extent. The proper ratio between upper and lower radii and space angle can reduce the residual stress to a certain extent. This can provide a preliminary optimization design scheme for air-film cooling blade and hole drilling.