Influence of the Groove-Patterned Cooling Tube on the Film Cooling Performance of Gas Turbine

The gas turbine performance significantly depends on the temperature of working fluid. In order to improve the efficiency of gas turbine, it is required to increase turbine inlet temperature. However, the working fluid in high temperature conditions causes thermal stress which could damage turbine blades. One of the methods to require turbine blades by controlling the temperature of working fluid is a film-cooling method. In this study, cooling tubes with various aspect ratios of groove length (L/L_t) with groove diameter of d = 1.2 mm were considered to enhance the film cooling efficiency. In addition, effects of blowing ratios (M) and diffuser angles (δ) of the cooling tube were considered. Numerical investigations were conducted using ANSYS ver. 17.1, and film cooling efficiencies of each case were obtained. Especially, the case with groove length aspect ratio of L/L_t = 0.4 at blowing ratio M = 1.4 and diffuser angle δ = 3.5° showed the highest cooling efficiency of 18% among all model cases.