A high fidelity ball bearing and damper model including thermal effects for magnetic suspension auxiliary service and blade loss simulation

In this dissertation, a high fidelity ball bearing and squeeze film damper (SFD) model including thermal effects is developed for two applications: (a) auxiliary or catcher bearings (CBs) in an energy storage flywheel system levitated on magnetic bearings (MBs), (b) support bearings of power turbine rotor in an aircraft gas turbine engine. A high fidelity ball bearing model allows individual ball and race degrees of freedom and a modified Hertzian contact load between the balls and races, and predicts ball contact load and stress. Temperature increases and corresponding expansions of bearing components are estimated using a 1D bearing thermal model, and contact load changes due to the expansions are considered in ball bearing dynamics. A SFD model, based on finite element method, determines pressure distribution of oil film according to the motion of damper journal, calculates pressure-induced viscous damping force correcting oil film cavitation and predicts power loss due to viscous dissipation in oil film. To validate the high fidelity ball bearing and damper models with thermal effects, their analytical results are compared with the analytical or experimental results from several references.; Using the developed model capabilities, a variety of simulations for the energy storage flywheel system are conducted to investigate the effects of CB design parameters on the dynamic responses of flywheel rotor drop on CBs. The used design parameters are friction coefficient on rotor/CB inner race contact area, axial preload, SFD oil viscosity and side loads from MBs. The simulation results from the linear CB model are compared to those from the nonlinear CB model to explore the effects of nonlinearity of the Hertzian contact load and those of the thermal expansions of bearing components on the rotor drop dynamics. CB design guides to provide safe landing of rotor and to prevent destructive high speed backward whirl are presented based on performance indices from the simulation results.; In the blade loss simulations, the high fidelity models are employed in a flexible dual-rotor gas turbine engine composed of power turbine and gas generator rotors. The modal truncation augmentation method is used as an efficient tool for modeling the gas turbine engine with 38 lumped masses. As the imbalance force in the power turbine rotor is increased, the dynamic responses of the power turbine and damper journal, ball contact loads and stresses, transmissibility at the support bearings, and thermal increases of the bearings are presented.