August 15, 2017
The HiFrancis Project
There have been a series of failures in high head Francis turbines in the latest decades. In the Norwegian hydropower industry, there is currently a cooperative effort for solving this problem, called the HiFrancis project. The turbine failures are caused by fatigue cracks in the runner, originating from the pressure pulsations in the turbine. The HiFrancis project looks to investigate the Fluid-Structure Interaction (FSI) in the turbine, and develop robust design procedures for the future.
EDR&Medeso are the main responsible for the numerical simulations in the project, the Norwegian University of Science and Technology does the physical experiments. The current status on the numerical side is that the pure CFD simulations are soon to be done! EDR&Medeso will by the end of Q3 17 present a Recommended Practice (RP) on the findings so far. The RP will be expanded as soon as the structural and FSI parts of the project finalizes. Furthermore, a first version of an ANSYS toolkit is under development. The toolkit aims to streamline the work process to eliminate human error, but does also have some interesting features installed;
- Fourier based, reduced geometrical modeling for the pressure field in the runner
- Modal analysis of submerged runner
- Krylov based, reduced order modeling for rapid calculation of the harmonic response of the runner.
Some of the aspects that are being investigated as we speak, are the effects of fluid dampening on the eigenfrequency of the structure, and whether the fluid velocity or deflection amplitude affects the calculation of the dampening coefficient. This will be directly implemented in the harmonic response calculation when available.
Obviously, the toolkit is going to be continuously improved, with a final goal of complete fatigue lifetime estimation, and digital-twin capabilities. Stay tuned!
Read more about - HiFrancis Project here