Impact of non-uniform CMAS deposition and penetration on the performance degradation of a film-cooled vane with TBCs under a hot streak condition

Abstract

This paper presents a model and computational method to analyze the impact of CMAS deposition and penetration on the aerodynamic performance, cooling efficiency, and stress evolution of a film-cooled turbine vane under a hot streak condition. The results indicate that the insulation effect of the deposit layer enhances the vane's cooling efficiency as it thickens, leading to reduced temperatures within the coating and a decreased CMAS penetration rate. However, CMAS penetration increases the thermal conductivity of the coating, thereby diminishing its insulation effectiveness. After 1500 h of deposition, the CMAS penetration coefficient decreases by 11.8 %, while the thermal conductivity of the top coat (TC) increases by 8.93 %. Cooling efficiency improves by 2.1 % after 1500 h due to deposition, but this effect diminishes to 1.06 % because of CMAS penetration. Additionally, the thermally grown oxide (TGO) increases from 1.0 μm to 1.729 μm after 1500 h, and further to 1.761 μm with CMAS penetration. CMAS penetration results in a maximum stress increase of 34 MPa in the TGO after 1500 h, indicating significant stress accumulation in the TGO, followed by the bond coat (BC) and top coat (TC).