Numerical simulations of fatigue crack growth in a steam turbine rotor blade groove

Abstract

With increasing share of renewable energy sources in the electricity production strict demands are placed on thermal power plants that have to cover the power shortages more frequently. Increasing number of steam turbine (ST) start-ups and shutdowns, as well as requirements on higher ramping of operating conditions, has detrimental effect on the overall lifetime of ST components. In the ST design process, this situation has to be dealt by applying advanced prediction methodologies handling the thermo-mechanical fatigue mechanism, for instance. On the other hand, in the case of currently operating STs, regular inspection and maintenance schedule as well as technologies for turbine operation control have to be reconsidered or newly developed. To cope with these challenges, the international consortium of energetic turbine producers and research institutes initiated the TURBO-REFLEX project funded by EU's H2020 program. One of the principal aims of the project is development of a damage tolerance approach that may be suitable for scheduling the ST rotor maintenance, for instance. Decisive factors in this effort are ST rotor operating conditions, material fracture properties and geometry that constitute the crack initiation site and crack growth rate and direction. This forms a complex task that has to be handled numerically by using a Finite Element (FE)-based code accompanied by in-house scripts for detecting the most probable way of crack propagation. In this contribution, the adopted fracture-mechanics approach applied to low-pressure section of ST rotor and results that have been achieved are presented.