Numerical investigation on life improvement of low-cycle fatigue for an ultra-supercritical steam turbine rotor

In this paper, an axisymmetric rotor of a 1000-MW ultra-supercritical steam turbine was modeled with the commercial finite-element software ABAQUS with inlet parameters of 35 Mpa and 600A degrees C. The temperature and Mises stress distributions of the rotor during the start-up procedure were then analyzed. The fatigue damage was predicted by the strain-life-based Manson-Coffin equation and the Miner rule. The results demonstrated that the fatigue damage was mainly generated at the rotor surface. For the requirement of the half life time, the cyclic number almost reached 4000. Furthermore, optimization by extending the warm-up phase is proposed to eliminate strain fluctuations and further decrease fatigue damage. The results showed that the fatigue damage significantly decreased at four key locations. The fatigue life during the start-up phase was improved.