Thermo-mechanical analysis of TBC-film cooling system under high blowing ratio considering the effects of curvature

Understanding the thermo-mechanical behavior of thermal barrier coating (TBC)-film cooling system under different curvatures is crucial for predicting the failure of turbine blade and improving its reliability. In this work, a thermal-fluid-structure coupling method was implemented to systematically explore the cooling efficiency and interface stress of the TBC-film cooling system with different curvatures under steady-state and transient conditions, predict the location and potential causes of coating failure, and provide guidance and suggestions for the structural design of blades. The results showed that the cooling efficiency and interface stress of the system were closely related to curvature. Model I and Model II cracks may be induced by normal and shear stresses generated at the edge of the cooling hole and interface. The growth of thermally grown oxide and the yield behavior of bond-coat have a significant impact on the stress level of coating system. The most dangerous area was located downstream of cooling hole at the thermally grown oxide and bond-coat layer interface. Additionally, due to mainstream ingestion, the concave model was more susceptible to high transient stresses during the heating stage, while the convex model was more likely to induce higher thermal mismatch and residual stresses during the stabilization and cooling stages, leading to coating failure.