Dynamic Behaviour in a Hydro Power Rotor System Due to the Influence of Generator Shape and Fluid Dynamics

Hydro power rotors are subjected to fluid and electromagnetic forces. In this paper measurements and simulations are shown for a hydro power rotor system. The simulation includes the influence of fluid forces in the turbine as well as the electro magnetic pull in the generator. The mechanical rotor system is modelled with the generator and the turbine treated as two rigid bodies, connected to an elastic shaft supported by three bearings. The fluid model in the turbine is based on results from the scientific literature. A model is suggested for the electro magnetic pull due to eccentricity and the shape of the stator core and the rotor rim. Results from the simulation are compared and analyzed with frequency spectrum from vibrations measurements. One can conclude that the unbalance together with geometric properties of the turbine and generator, are possible sources of the most dominant frequency peak in the measurements.