A Study on the Aerodynamic and Heat Transfer Performance of Gas Turbine by Degradation of Surface Roughness

As the efficiency of the gas turbine increases with the increment of turbine inlet temperature. The roughness of the thermal barrier coating determines the efficiency and heat transfer characteristics of the turbine. The roughness quality of the thermal barrier coating is very significant in the regeneration process of gas turbine parts. In this study, the flow and heat transfer characteristics due to the degradation of the thermal barrier coating on the gas turbine surface are numerically studied. Surface roughness measurement equipment is used to measure the surface roughness of the thermal barrier coating on the blade which is used for 24,000 hours and 48,000 hours, and applied the same conditions in the numerical analysis. The turbulence model is applied to the k-omega SST model and the turbulence intensity at the inlet is assumed to be 20%. Surface roughness is set by converting to sand grain roughness. To accurately predict the effects of roughness, the maximum y plus is designed to be less than one. The total pressure loss coefficient of vanes and blades with degradation of the surface roughness increases to 0.0136 and 0.2372, respectively, compared to the smooth wall condition. Moreover, the heat transfer coefficient on the suction side increases with the increment of surface roughness. This study is expected to be used in the regeneration maintenance and heat transfer characteristics of gas turbines.