Coupling analysis of tribological and dynamical behavior for a thermal turbulent fluid lubricated floating ring bearing-rotor system at ultra-high speeds

The floating-ring bearing supported turbocharger rotor system generally reaches the speeds exceeding 100,000 rpm in high-temperature environment, but the risky sub-synchronous whirl, oscillation, bifurcation, and chaos probably appear due to its unsteady hydrodynamic forces with the high shear rate and low viscosity lubricant. From this perspective of coupling tribology and dynamics, the transient acting pressures at the thermal double fluid-film bearing are computed by employing the turbulent lubrication theory, then a numerical model for the whole rotor-bearing system based on the transfer matrix method is developed to investigate its nonlinear vibration behavior. The results show that an "interval region" characterized by the synchronous unbalance vibration is available to avoid fluid-induced instability of this system at different high-speed requirements.