Passively Enhancing Gas Thrust Bearing Performance Through an Inexpensive and Straightforward Design Optimization of the Rotor Disk

Abstract This article presents an inexpensive passive approach for reducing the thermal bending deformations of rotor disks in gas thrust bearings, featuring an optimized design for the rotor disk. Small geometry changes are incorporated and inertia effects are utilized in order to compensate the thermal bending deformations, increasing bearing performance markedly. A fully coupled, multiphysical nonlinear finite element model is used to model the foil thrust bearing. This model is used to analyze the deformations and temperature of the bearing foils, the pressure and temperature distribution within the lubricating air gap as well as temperature and thermo-elastic deformations of the rotor disk. Additionally, heat fluxes through the rotor and an entire machine assembly including journal foil bearings, the machine housing, and an electric motor are represented. The simulation results of the foil thrust bearing with the newly optimized rotor disk design are compared against a standard symmetric thrust disk design. Results indicate that the thrust load capacity of the foil bearing can be increased markedly by implementing the proposed small changes to the rotor disk design. With the help of this detailed model it is possible to provide a reasonable estimation of the impact of the optimized rotor disk design for real turbomachinery applications.