FINITE-ELEMENT ANALYSIS OF THE 3-DIMENSIONAL TRANSIENT TEMPERATURE-FIELD IN STEAM-TURBINE CASINGS

One of the important considerations going into the process of optimiza tion of start-up schedules for steam turbines is the estimation of the rmal stresses during the transients. This in turn requires prediction of the transient temperature fields. In the case of the turbine casing , the procedures are complex in view of the irregular geometrical shap e. Finite element analysis offers better scope in this regard and has been employed in the present work to compute the 3-D transient tempera ture distribution in the casing metal. The results obtained by a code developed for a specific type of turbine casing have been compared wit h the values measured by experiment and have been found to validate th e code. Time-temperature histories for two typical locations inside th e casing metals are presented. Isotherm surfaces across the metal at a given instant are shown.