Vibration of large turbo-rotors in fluid-film bearings on an elastic foundation

In the first sections of this paper the flexible rotating shaft of a turbo-rotor is treated by finite element analysis. Internal and external damping, gyroscopic forces, fluid-film forces, aerodynamic cross-coupling from steam flow and magnetic pull are taken into account. Although some hundred degrees of freedom have to be introduced to describe a realistic turbo-rotor, computational effort can be enormously reduced by making use of the banded structure of the system matrices.In the second part foundation dynamics are introduced into the rotor equations via a receptance formulation. The receptance matrices of the foundation or supporting systems can be obtained either from shaker tests or from the mode analysis of the foundation without shaft. Numerical examples are given.