Advanced simulation of coupled physics in thrust bearings

Abstract

In hydro power units with very large reversible pump turbines, tilting pad thrust bearings may operate at the edge of the field of experience regarding sliding speed, contact pressure, size, and shape. Here, advanced numerical simulation methodologies offer the possibility to precisely predict the bearing performance and to safely reach guaranteed properties while minimizing the need for experimental investigations. Hence, objective of this work is to develop and validate an advanced method which fully resolves coupled physics in large thrust bearings of reversible pump turbine units. By applying this method, layout tools can be validated and calibrated for an extended design space. Moreover, a better understanding of physical phenomena and how they interact allows for the improvement of design standards. The present contribution introduces an accurate and robust coupling and solution procedure including finite element analyses of thermal and mechanical deformations of pad and thrust runner, mesh motion analyses, and conjugate heat transfer (CHT) analyses. CHT analyses account for flow and heat generation in oil film and groove as well as heat transfer in pad and runner. By applying the procedure to a large bearing investigated at a prototype-sized test rig, all analysis steps are verified and validated using accurate and extended measuring data.