Pre-compensated design and performance validation of a TBC-film cooling system considering blockage effects

The material temperature capability used in hot-section components of aero-engines is far lower than the surrounding gas temperature, making thermal protection essential to ensure safe service operation. Taking turbine components as an example, external cooling is commonly achieved through a combined application of TBC and film cooling. The former increases the external thermal resistance to suppress heat flux into the substrate, while the latter reduces the convective temperature at the external surface. However, the TBC-film cooling system exhibits strong mutual interactions, causing the actual thermal protection performance to be inferior to the linear superposition of the two individual techniques. Among these interactions, exit blockage induced by TBC deposition at the film hole represents one of the most typical and detrimental forms. In the present study, a pre-compensation design method is proposed to mitigate TBC-induced deterioration of film cooling by introducing a diameter enlargement factor. Large-eddy simulation is employed to systematically investigate the influence of blockage on jet behavior and to evaluate the effectiveness of the proposed method. The results demonstrate that, under blocked conditions, the pre-compensation design effectively preserves film cooling performance, and at a blowing ratio of 1.5, the surface-averaged film cooling effectiveness is enhanced by up to 6.7%. Furthermore, by reducing ribbon-like vortical structures and high streamwise vorticity micro-clusters, the pre-compensation design significantly improves the flow stability of the film cooling jet.