EFFECT OF THERMAL BARRIER COATING SIMULATION METHOD ON COOLING CHARACTERISTICS OF TURBINE VANES

Thermal barrier coating (TBC) is widely used in turbine vanes relying on the good thermal resistance, corrosion resistance. It is of great significance to accurately simulate the flow and heat transfer characteristics of coated vanes. However, there is no uniform standard for the simulation method of TBC. In this paper, the numerical study of vanes with a single-layer coating was conducted. The effect of the simulation methods (real model, called Method-1, and virtual thin-wall, called Method-2) on the flow and heat transfer characteristics was investigated under different TBC properties and turbulence intensity (Tu). The results showed the mass flow of film cooling on the suction surface of real TBC vanes was reduced by 25.5 %, when the TBC thickness was 0.3 mm. The TBC temperature differences between the two simulation methods on the overall and section surfaces were 5.4 K and 25.4 K. The TBC temperature was more sensitive to coating simulation methods. Modifying the property, the change of TBC temperature was the smallest at the leading edge, about 6.5 K. While the change of metal temperature was the largest there, about 37 K. The larger the thermal conductivity, the larger the metal temperature difference and the smaller the TBC temperature difference, which were caused by simulation methods. The sensitivity of temperature to Tu was relatively low for Method-1. As Tu increased, the absolute value of temperature difference on the section between simulation methods decreased first and then increased, and it decreased gradually on the overall surface. Finally, a simplified simulation method (Method-3) was proposed, in which the metal surface was thickened outwards with the virtual thermal conduction resistance added at the interfaces. And the accuracy of this method on the heat transfer characteristics of vanes with a double-layer coating was verified. For all turbulence intensity, the differences of coolant mass flow and temperature between Method-1 and Method-3 were less than 0.15 % and 2 K, respectively.