Modell of a bladed Jeffcott rotor

Nonlinear dynamics of hydro power rotors

Published: 25 January 2012

The aim of the project is to evaluate the limits of linear modeling of hydropower rotors. Weak nonlinear interaction in bearings, electromagnetic forces and fluid interaction in turbines are typical nonlinear effects in hydropower rotors. These types of nonlinearities can even be strong in case of bad design of the rotor. Moreover, strong nonlinearities can also occur due to turbine contacts or assembly errors. As a result, a large range of typical rotors are studied, starting from a bladed Jeffcott rotors attached to a snubber ring to more realistic models with complex geometry generated with Finite Elements, and adding the nonlinear effects that can be encountered in hydropower. Studies of nonlinearities are performed using common tools such as bifurcation diagrams, Poincare sections or Lyapunov exponents.

The results obtained are also compared with real hydropower rotors to validate the models proposed.  From these comparisons, general tools can be developed to evaluate the robustness of any hydropower rotor, as well as a methodology of study which could be also applied to any type of rotor in general.

PhD: Florian Thiery
Supervisors: Jan-Olov Aidanpää (LTU) och Rolf Gustavsson (Vattenfall)

The project is supported by Svenskt vattenkraftcentrum, SVC