General presentation > Keynote speaker

Andreas Schubert

R&D  Lead Engineer - Mechanical

GE Renewable Energy

Birr, Switzerland

Biography

Andreas Schubert received an MSc degree in Mechanical Engineering from the Technical University in Karlsruhe, Germany in 1980. Since 1981 he works as a development engineer for Alstom and today for GE. The first 19 years of his career, he worked for industrial steam turbines in Nuremberg, Germany. In 2000, he moved to Global Technology Centre for hydro generators in Birr, Switzerland. His main research topics are hydrodynamic bearing simulations, rotor-dynamics and high speed rotor balancing. In 2008 he was nominated as a Principal Engineer, specializing in bearing design and the development of bearing calculation tools. He works since 1983 in FVV (Research Association for Combustion Engines e.V.) in Germany and is leader of the bearing group. The organization FVV coordinates research and development between industry and university.

Special operating conditions of bearings: Application to tilting pad thrust bearings of vertically aligned hydro machines.

Hydrodynamic bearings of rotating machines are mainly designed for the rated operating conditions. However, the transient conditions influence the bearing size too. In vertically aligned hydro machines from GE, the thrust bearing supports the high load because of the rotor weight and the axial hydraulic load. The guide bearings support the lower radial loads. Transient conditions with their influence on the bearing design are the focus in this presentation.

The transient regime occurs for example during start-up and shutdown periods, during heating of the oil due to lack of cooling capacity or a rapid speed increase due to runaway. During these relatively short periods of time the bearings operate with thinner oil films and higher temperatures. Consequently, other load capacity design limits than for rated operating condition must be used. Calculation methods to estimate the transient behaviour like FSI (Fluid Structure Interaction) will be described.

In extreme cases a mixed friction could happen at low speed or very high load. Some latest updates on research and development regarding this topic will be also reported.

Modern bearing coating materials can influence the behaviour at transient and mixed lubrication regimes. The conventional Whitemetal (Babbitt) coating with a temperature limit near 120°C could be replaced by other materials for example by polymers with higher temperature limits and lower wear.