Impact of Cooling with Thermal Barrier Coatings on Flow Passage in a Gas Turbine

Abstract

Inlet temperature is vital to the thermal efficiency of gas turbines, which is becoming increasingly important in the context of structural changes in power supplies with more intermittent renewable power sources. Blade cooling is a key method for gas turbines to maintain high inlet temperatures whilst also meeting material temperature limits. However, the implementation of blade cooling within a gas turbine—for instance, thermal barrier coatings (TBCs)—might also change its heat transfer characteristics and lead to challenges in calculating its internal temperature and thermal efficiency. Existing studies have mainly focused on the materials and mechanisms of TBCs and the impact of TBCs on turbine blades. However, these analyses are insufficient for measuring the overall impact of TBCs on turbines. In this study, the impact of TBC thickness on the performance of gas turbines is analyzed. An improved mathematical model for turbine flow passage is proposed, considering the impact of cooling with TBCs. This model has the function of analyzing the impact of TBCs on turbine geometry. By changing the TBCs’ thickness from 0.0005 m to 0.0013 m, its effects on turbine flow passage are quantitatively analyzed using the proposed model. The variation rules of the cooling air ratio, turbine inlet mass flow rate, and turbine flow passage structure within the range of 0.0005 m to 0.0013 m of TBC thicknesses are given.