Thrust Bearing Influence on the Stability Analysis of Turbocharger Rotor-Bearing System

The paper focuses on modeling and dynamic analysis of an on-board rotor over the floating-ring bearings by considering the additional effects due to a thrust bearing and axial preload. Initially, finite element analysis is used to get the unbalance response of the rotor system. The unsteady Reynolds equations are solved using finite difference approach with appropriate boundary conditions for finite length case. The time-varying bearing forces along with the rotor system of equations are solved by time-integration schemes. Further, the thrust bearing at the compressor end is modeled by its equivalent springs to study its influence on the stability of the overall system. The dynamic response of the system is investigated for various stiffness and axial preload condition at different rotor speeds. In addition, the influence of the thrust bearing forces on the overall dynamic stability of the rotor is studied. It is identified that the influence of thrust bearing forces is relatively small on the unbalance response at higher speeds of operation.