Influence of thermally induced changes in lubricating gap clearance and oil viscosity on nonlinear oscillations of hydrodynamically supported rotors

Despite many advantages, hydrodynamic bearings tend to induce nonlinear vibrations on rotor systems at low external loads. The occurrence and also the amplitudes of these are very sensible operating conditions system such as gaseous cavitation, oil viscosity (strongly dependent temperature), bearing clearance (dependent metal temperature thermal expansion coefficients) or imbalance. This contribution shows calculation oscillations with help a detailed transient 3D-thermo-hydrodynamic model. Referring experimental data real exhaust turbocharger semi-floating ring bearings, this holistic approach is used for separate investigation a) influences temperature-dependent in lubricating films b) temperature-related changes gap rotor.