Crack Management on Hydroelectric Turbine Shafts
Brookfield commissioned Lx Sim to assess fatigue cracks caused by corrosion observed on its bulb-type hydroelectric turbine shafts. An initial fatigue-based evaluation suggested that the alternating stresses caused by shaft reverse bending were too high to be sustained over time. As a result, all unit shafts were to be replaced urgently, leading to major logistical challenges and potential revenue loss. Lx Sim proposed an alternative approach to validate the residual life of the components and optimize the replacement planning.
Challenges
- Understand and analyze the propagation of corrosion-fatigue cracks in a submerged environment
- Avoid costly and premature replacement of turbine shafts
- Find alternatives to crack excavation, which was not sustainable and often worsened the issue
Solutions
LEFM Analysis (Linear Elastic Fracture Mechanics)
- Application of fracture mechanics methodologies adapted to corrosion-fatigue
- Advanced numerical simulations to help predict crack behavior
Targeted Recommendations
- Development of inspection protocols and comprehensive documentation to ensure rigorous crack monitoring
- Definition of clear criteria to determine the optimal timing for shaft replacement across all units
Results
Thanks to our simulation expertise, LEFM analyses, and a rigorous monitoring plan:
- Cracked turbine shafts were able to continue operating safely over an extended period
- The client was able to plan production shutdowns optimally, significantly reducing financial risks associated with immediate replacement
- A documented and proven inspection process ensured long-term equipment reliability and compliance
By leveraging innovative numerical simulation approaches, this project turned a challenge into a strategic opportunity. The client was able to delay premature component replacement while proactively and efficiently planning interventions.