Advances in Steam Path Technology

Abstract

For many years, GE has been conducting research to understand better the loss mechanisms that degrade the aerodynamic performance of steam turbine stages, and to develop new computational fluid dynamics (CFD) computer programs to predict these losses accurately. This paper describes a number of new steam path design features that have been introduced in the GE steam turbine product line to improve turbine performance and reliability. These features include diaphragms with contoured sidewalls, advanced vortex blading with compound tangential lean, new continuously coupled last-stage buckets with improved aerodynamic efficiency and reliability, improved downward and axial flow exhaust hoods, and better steam leakage control devices. The benefits of these new features for both new units and retrofits of existing units are discussed. In addition, the paper discusses the new generation of three-dimensional viscous CFD analysis codes being used to develop new design concepts, including codes developed by GE as well as those obtained externally. Also described are the extensive laboratory test programs being conducted to validate the CFD codes and verify the predicted efficiency gains for new design features. Last, the paper describes new and unique state-of-the-art steam path design automation and optimization tools that dramatically reduce the design cycle time for new advanced aerodynamic designs.