Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2018-2019)

Modern hydroelectric turbines are designed to achieve near perfect efficiency while keeping production costsx000D
as low as possible. One way to accomplish such a goal is by reducing the thickness of turbine blades,x000D
consequently lowering their stiffness and increasing their propensity to experience critical vibration levels.x000D
Moreover, the end-users' growing need for power regulation due to the integration of intermittent renewablex000D
sources leads to more frequent off-design operations as well as machine starts and stops, for which dynamicx000D
mechanical stresses are significantly higher than at best efficiency point. In this context, precise knowledge ofx000D
the turbine dynamic characteristics, notably the variation of the natural frequencies of the rotor with rotationx000D
rate, is essential to avoid problematic vibrations. In many publications, pump-turbine runners have beenx000D
modelled using a rotating disk submerged in water, highlighting the phenomenon of frequency split: a forwardx000D
and a backward travelling waves emerge as the disk rotate. This phenomenon is linked to the variation of addedx000D
mass with rotational velocity. The project has two main objectives: understand better the mechanism ofx000D
frequency split; and develop a simplified simulation strategy to evaluate the natural frequencies of a rotatingx000D
disk. Understanding the frequency split of pump-turbine runners and its underlying mechanisms is critical tox000D
evaluate the resulting stresses and the expected life of the machine. This project will provide an accurate andx000D
fast tool to improve the design of high head Francis turbines and pump-turbines. This tool is essential tox000D
develop new reliable turbines and provide detailed information about the fatigue life of the equipment.