Theoretical and Numerical Study on Thermal Insulation Performance of Thermal Barrier Coatings

Abstract

In this article, a theoretical 1-D heat transfer model and conjugate heat transfer numerical simulation was carried out to evaluate the thermal insulation of TBCs under different factors. The relationship of temperature-drop between the inner or outer surface of thermal barrier coating (TBC) was investigated by conjugate heat transfer numerical simulation. The effect of TBC and the coupling between the internal and external heat transfer are obtained, which indicates that TBC and film cooling can both contribute to an overall cooling performance. In addition, the combination of the two results are better results than the two alone. However, the two weaken each other’s contribution to the overall cooling performance. Meanwhile, unlike the effect of film cooling, the change in the internal heat transfer coefficient basically does not affect the thermal insulation effect of coatings. Furthermore, sensitive analysis on the different levels of film cooling and coating’s thermal insulation was conducted to the overall cooling effectiveness, with the blowing ratio ranging from 0.25 to 0.5, thermal resistance ratio ranging from 3 to 9, and the internal heat transfer coefficient ranging from 5000 W/(m2∙K) to 15,000 W/(m2∙K). The results reveal that near the exit of the film hole, film cooling plays a major role in the overall cooling effectiveness. However, with the increase in dimensionless distance, the contribution of coatings and the internal heat transfer coefficient to overall cooling effectiveness gradually increases, especially the contribution of coatings.