Thermo-Structural Analysis of First Stage Gas Turbine Rotor Blade Materials for Optimum Service Performance

Abstract

During gas turbine operation, the vibration that occurs at high speed, hot gases entering the combustion chamber and other operational factors affect the longevity of gas turbine blade. This paper is focused on the selection of suitable materials that can withstand the severe working condition and thermo-structural analysis using Finite Element method (FEM) to determine the behaviour of each material under service condition. Cambridge Engineering Software (CES) was employed in the material selection process where GTD111, U500 and IN 738 were identified prior to analyzing U500 and IN 738 due to desired mechanical properties over GTD111. Employing ANSYS R15.0 in the steady state thermal analysis, maximum service temperature of 736.49oC and maximum Total heat flux of 4.345x105 W/m2 was obtained for IN 738 material while maximum service temperature of 728.29oC and maximum Total heat flux of 4.1746x105 W/m2 was obtained for U500 blade material. For structural static analysis, maximum von-mises stress of 454 MPa and total deformation of 0.16221 obtained for IN 738 while maximum von-mises stress of 416 MPa and total deformation of 0.12125 was obtained for U500 blade material. While the FEA analytical results for both materials exhibited less variations between each other, IN 738 displayed better thermal characteristics, whereas, U500 presented satisfactory structural static results and above all, von-mises stresses obtained for both materials was below their yield strength and melting temperature. Hence, gas turbine blade materials should be assessed thoroughly for structural and thermal conditions before manufacturing.