Life prediction of C3X gas turbine Blade of CMSX-4 material

Abstract

ABSTRACT Life prediction plays an important role in avoiding the catastrophic failure of a gas turbine blade subjected to simultaneous high thermal and mechanical load. The purpose of this paper is to predict the life of C3X blade of a nickel-based single crystal super alloy, CMSX-4 material under thermo-mechanical load at four different operating conditions. The blade was geometrically modelled and by using computational fluid dynamics approach with k-ε turbulence model the distribution of temperature, pressure and heat transfer coefficient on the surface of the blade was determined. Mechanical and thermal were determined by uncoupled heat transfer analysis and thermomechanical stresses by sequentially coupled thermo-mechanical stress analyses for a flight length of 5000 seconds. Finally, life of the blade was estimated considering fatigue-creep interaction by applying ductility exhaustion method and morrow mean stress correction. The results show that the critical damage occurred at trailing edge and fixed portion of the blade. In comparison to the mechanical or thermal load, there is a significant change in stress magnitude for the thermo-mechanical load. Also, the blade radial displacement is mainly ascribed to the thermal load rather than the mechanical load.