Accurate prediction of thermal insulation performance for porous thermal barrier coatings under aero-engine in-service conditions

The continuously increasing working temperature of advanced aero-engines demands the development of high-performance thermal barrier coatings (TBCs) to prevent the failure of hot-end components such as turbines. However, severe in-service conditions and complex pore microstructure of TBCs bring significant challenge to the evaluation of thermal insulation performance. Therefore, this paper investigates the effects of in-service conditions and microstructure on TBCs thermal insulation performance. The results indicate that under the in-service conditions of TBCs, the radiative heat dissipation mechanism inside pores shows remarkable influence on thermal insulation performance. Due to the overlook of radiative heat transfer in TBCs, the conventional effective thermal conductivity model which is based on homogenized assumption leads to thermal insulation performance evaluation error of 6.03% for typical TBCs. With the variation of porosity and pore size, the evaluation error can be further enhanced and the maximum error can reach up to 16.71%. Based on this, a predictive model of effective thermal conductivity considering effects of in-service condition and pore microstructure is further proposed. Compared with the conventional model, the evaluation error reduces from 16.71% to 1.71%. This work establishes a rapid and accurate approach for thermal insulation performance evaluation, which can advance the design efficiency of TBCs.