Stability and Hopf bifurcations in rotor-bearing-foundation systems of turbines and generators

The paper investigates the type of Hopf bifurcations existing in slender rotor systems of turbines and generators with respect to the design of bearings, foundations, and rotors. Two bearing profiles applied mostly in such rotor systems, the lemon bore and the partial arc bearing are considered in the analysis with nonlinear impedance. Simplistic models of single degree of freedom per direction are considered for the bearing pedestals. Part of the paper investigates the bifurcation type in simple Jeffcott rotor mounted on nonlinear lemon bore and partial arc bearings with resilient pedestals, aiming to raise design concerns which influence the type of bifurcation. The results highlight the need for nonlinear stability assessment in the standard design of turbines and generators.