This work by Maxime Favario proposes an experimental study of the splashing of a Pelton turbine, A phenomenon corresponding to the partial immersion of the wheel of a Pelton turbine due to a rise in the water level in the pit and tailrace. This phenomenon can occur in high head hydroelectric installations, during a flood or a change in the operation of the power station.
The study is being carried out on a model Pelton turbine with four injectors developed by the Hydro Alps Lab at the HES-SO Valais. After determining the best operating point (BEP), the head of water in the tailrace is gradually increased in order to induce splashing. The impact on performance is analysed by measuring torque, hydro-mechanical efficiency and vibrations. Particular attention is paid to two-phase air-water phenomena, in particular the formation of bubbles and their evacuation, which are studied using dedicated sensors and on-board camera visualisations.
The results show a significant reduction in torque and efficiency, accompanied by an increase in vibrations during sparging. This study contributes to a better understanding of the physical mechanisms involved and provides useful elements for the analysis, design and safe operation of Pelton turbines subjected to degraded downstream flow conditions.
