Effects of Design Variables on High Cycle Fatigue in Steam Turbine Stages

Modern steam turbine designs are exploring wider design space to gain improved performance. At the same time, the mechanical integrity of the steam turbine needs to be maintained. This requires an in-depth understanding of the effects of each design variable on High Cycle Fatigue (HCF) of a steam turbine stage. In a previous paper, effects of both Blade Count Ratio (BCR) and Gap Ratio (GR) were studied in a steam turbine stage. This paper studies the HCF of a new rotor blade with a narrower chord, which shows higher response. Furthermore, the effect of stagger angle of the stator blade is investigated. Their effects on aero forcing, aero damping and frequency shift are also demonstrated. A one-way coupling approach is used in this study due to its high computing efficiency.