Determination of added parameters in hydraulic turbines

Swedish hydroelectric power units are mainly equipped with Kaplan and Francis runners. Today, additional parameters established several decades ago are used to describe how these parameters, which are affected by the presence of water, influence the characteristics of the runner for safe operation. However, these parameters need to be updated to also apply to refurbished runners that are lighter and more powerful.<br>Translated with DeepL.com (free version)

The design of Kaplan and Francis runners requires determining the characteristics of the runner, such as its natural frequencies, to ensure safe operation. Such an analysis requires knowledge of the additional characteristics (mass, damping, stiffness) that the water induces on the runner to make a correct assessment. These additional parameters are difficult to determine because they depend on many factors such as vibration frequencies, amplitude, velocity field, viscosity, turbulence, head, geometry, and more. For refurbished impellers, which are lighter and more powerful, a more accurate determination of these parameters is required, but there is currently no established method for how this should be done.

The project aims to develop a numerical methodology for determining additional parameters in Francis and Kaplan turbines. The methodology will be validated using measurements performed at Vattenfall’s laboratory.