Switzerland's strategic goal to increase hydropower electricity production to 37,400 GWh by 2035 and 38,600 GWh by 2050 highlights the critical role of hydropower in securing the national energy supply. However, hydraulic concessions representing 23 TWh (65% of annual hydro generation) are set to expire over the next 30 years, and to remain compliant with the complex Federal Act on the Protection of Waters (WPA), there is an urgent need for a thorough review of technical setups and operational strategies. Additionally, the shift towards flexible operation to guarantee the grid stability, perturbed by the rise of intermittent renewable energy sources, has shortened the lifetime of hydraulic machines. Understanding the root causes of this aging process and how fluid-structure interactions contribute to it is crucial for developing novel designs and precise monitoring systems.
The overarching goal of VORTEX-FLEX is to enhance the availability and resilience of hydropower plants equipped with reversible pump-turbines by studying the vortical structures that develop during start-up sequences and their impact on the impeller lifespan. Building on extensive prior research and leveraging advanced techniques for simulating, measuring, and analysing dynamic and transient flow phenomena in turbomachinery, this project aims to bridge critical data and methodological gaps. The key research objectives are: 1) experimental characterisation of the flow at the impeller outlet and in the draft tube during start-up using a reduced-scale model of a Francis-type reversible pump-turbine, 2) development of a novel experimental setup to reproduce and control vortical structures in a controlled environment, and 3) characterisation of the vortex dynamics in this novel setup and benchmarking findings against the reduced-scale model.
This collaborative effort, supported by industry and international research partners, will develop a new complementary experimental method to analyse fluid-structure interactions and build data-driven vortex dynamic models. The insights gained will improve predictive models for machine lifetime and maintenance intervals, and potentially lead to new mitigation strategies in the machine designs and operations to enhance hydropower plant resilience and operational flexibility. By aligning with several research priorities of the SFOE hydropower research program, VORTEX-FLEX aims to increase the operational flexibility and availability of hydropower technology, thereby securing Switzerland's energy supply.
