The Project – Hi Francis FSI Toolkit
EDRMedeso is proud to announce that is has been granted founding from the Research Council of Norway to undertake development related to FSI simulations on rotating equipment.
The funding is on more than one million Euro and the projects will run for four years, starting January 1st 2016. EDRMedeso will develop toolkits and procedures which make it possible to perform FSI simulations for accurate load prediction within an engineering timeframe. The goal is that FSI simulations will be used to accurately predict, and improve, the fatigue life of turbines and pumps
What shall we do – Fatigue failure
Fatigue failure caused by flow-induced vibrations is a significant challenge in several industries. Newly developed high head Francis turbines fail after just a few years of operation, pumps break down much before their estimated Life cycle and piping systems fail without any obvious cause. One common difficulty in addressing this challenge is to do a reliable calculation of the actual dynamic loading caused by the fluid. And, without reliable loads, it is simply impossible to calculate the correct fatigue Life.
In the current research project, EDRMedeso will develop a feasible methodology for fast and accurate simulation of FSI on rotating machinery. The procedure will describe, in detail, modeling techniques and valid assumptions to achieve reliable and accurate results. Furthermore, a software Toolkit supporting the recommended workflow will be developed. Mathematical models, that can be implemented to reduce simulation time, exist. The current pre- and post-processing is tedious and does not prevent human error. The Toolkit will be a product packaged in a user-friendly environment to secure reduced simulation time with respect to both CPU demand and human interaction.
Update, March 2017:
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.
EDRMedeso 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!