Thermal-Fluid-Solid coupling mechanism of a novel friction reduction cooling structure for gas turbine

Abstract

To supply the higher safety design demands of the new generation of gas turbines, it is urgent to solve the difficulties in mid-chord region of high-temperature turbine blades, including excessive friction loss of traditional two-pass channel, lack of experimental data, lack of stress-strain characteristics in the solid domain and so on. Therefore, this research aims to propose an integrated method of the high-efficiency and low-friction cooling design and Thermo-Fluid-Solid (TFS) coupling analysis. Firstly, a turbine blade rotating cooling experimental system is designed and built independently. Then, a novel friction reduction method with cross bridge structure is proposed. The friction reduction mechanism and the effect mechanism of the cooling performance on the solid strain are revealed through experimental test and TFS coupling numerical study. The results show that the cross brige has an excellent friction reduction effect on the channel. The influence of ‘peak cutting and valley filling’ effectively enhances the heat transfer uniformity as well as successfully reduces the overall strain. The average Nu/Nu0 of the leading edge surface decreases by 14.7% (stationary condition) and 16.4% (rotating condition), respectively. And the Nu/Nu0 of the trailing edge surface achieves a maximum improvement effect of 3.3%. The f/f0 of each channel decreases initially and followed by an increase as Ro increasing. Among them, the channel with two and three cross bridges can achieve friction reduction effects of 24.7–37.3% and 32.2–40.9%, respectively. The strain is related to the Nu/Nu0 of each region, and the value of the rotating trailing edge surface is generally higher than that of the rotating leading edge surface.