A study on cooling performance of surface-modified TBC-film cooling system with bio-inspired micro-riblets

Abstract the surface-modified film cooling, which can be realized by paving thermal barrier coatings (TBCs), is widely studied and is proven to be effective in improving cooling performance. In this paper, micro-riblets, a type of bio-inspired microscale surface patterns, were introduced for surface modifications of TBC-film cooling system and its improvement effects on cooling performance were mainly analyzed. In order to more accurately evaluate the flow field and temperature field of the model, the heat transfer effects of heat conduction, heat convection and heat radiation were considered, and the correctness of the calculation method was verified by compared with the experimental results. For the cooling performance under the condition of adiabatic wall, the model of micro-riblets surface could effectively improve the adiabatic film effectiveness compared with the flat-plate surface model, and the advantage was more obvious as the blowing ratio increased. In addition, the characteristics of conjugate heat transfer in the real serving environment were further considered. By analyzing the surface temperature of the TBC and the superalloy, the results showed that the micro-riblet structure could reduce the temperature of each layer of the model. The surface temperature of TBC-film cooling system with bio-inspired micro-riblets structure was cooled down with maximum amplitude of about 50K–60K. As the thickness of the micro-riblet increased, its cooling performance first increased and then decreased. Therefore, there is an optimal height of the micro-riblet structure that makes the cooling performance optimum.