Finite Element Analysis of Steam Turbine Components for Real Life Assessment Studies of 210 MW Steam Turbine

Abstract

The turbine rotor or steam turbine rotor is subjected to temperature variations in short periods of time due to the start and stop cycles of the turbine. This causes sudden changes in the temperature with transient thermal stresses being induced into the turbine rotor. The transient effect is due to the changes in the material properties like density, specific heat and Young’s modulus. The estimate of thermal stresses induced in the turbine rotor is important in determining the startup cycle of a steam turbine. Thermal gradients developed during thermal transients are the key source of stress generation in the rotor. The “heart” of these versatile machines is made by the blades and vanes, which are subjected during operation to very high thermal and mechanical stresses (combined effects of centrifugal force and thermal gradient).The high-pressure turbine model was prepared using CAD software (PRO-E) and axis symmetric F. E. model was analyzed for transient thermal and thermo-mechanical stresses using Ansys 11.The transient thermal and thermo-mechanical stress values found were within the yield strength of the material. It can be stated that the transient thermal and thermo-mechanical stresses are larger than the steady-state stresses. 

Keywords: Steam turbine rotor, transient thermal stresses, FEM, Ansys, transient thermo-mechanical stresses