Analysis of Conjugate Heat Transfer Between Cooling Film and Thermal Barrier Coatings Based on Micro-Structure

Abstract

Due to different preparation processes and long term operation, the micro structure of thermal barrier coating is different. The different micro structures have great effect on the thermal insulation properties of thermal barrier coatings and the conjugate heat transfer between the cooling film and thermal barrier coatings. In this work, different micro structures of thermal barrier coating were reconstructed using the scanning electron microscopy (SEM) images of two kinds of real thermal barrier coatings. The developed numerical calculation program based on the lattice Boltzmann method (LBM) was used to analyze the conjugate flow field and heat transfer between cooling film and porous thermal barrier coatings. The results show that the micro structures of thermal barrier coatings have a great influence on the stability of the surface film. Weak spatial variations in fluid velocity appear over the coating surface. The spatial variations in velocity over the layered coatings are larger because of its rough surfaces. The ratio of the vertical velocity to the bulk flow velocity can reach 2.5%. There is obvious vortex flow at the interface of coatings and cooling film, and weak flow in the interior perpendicular pores of the columnar coatings.