Gas Turbine Shutdown Thermal Analysis and Results Compared With Experimental Data

Abstract

Gas turbines undergo transient operation during startup, load change and shutdown. Understanding transient behaviour is very critical as it has significant influence on the safety and life of turbine components. The transient thermal analysis of the gas turbine is one of the most important aspects to evaluate the clearances and life of various components of the unit. The understanding of the shutdown phenomena is very complex due to huge transient variation in the temperature inside the turbine. In the shutdown process natural convection plays an important role as there is very less flow inside the turbine, which is difficult to model and predict with the current state of art tools. A Flange to Flange 2D axi-symmetric thermal model was considered for this analysis to predict the overall temperature distribution of the gas turbine components with suitable approximations. In this paper detailed experimental results of the GE frame 5 shut down are analysed and numerical modelling was attempted to match the experimental results. Several analytical studies are carried out to understand the various effects including the “heat soak” effect. These effects were captured in both experimental and analytical studies.