Integrated Three-Dimensional Thermohydrodynamic Analysis of Turbocharger Rotor and Semifloating Ring Bearings

Abstract

The mechanical performances of turbocharger rotor bearings system are strongly coupled with the thermal effects of lubrication. This paper built an integrated three-dimensional thermohydrodynamic model for the rotor and semifloating ring bearings. The thermal viscosity and non-Newtonian effects of lubricant oil are involved. Three experimental cases with different oil supply temperatures and pressures are conducted to validate the numerical results. The prediction coincides well with the measured results. Subsynchronous responses jumping between the conical and cylindrical mode shapes happens. The thermal results show that the heat conduction and expansion of the solid parts can affect the temperature fields and clearances of the oil films. Furthermore, for the bearings with axial grooves, the underdeveloped thermal boundary layers exist in the inner film at high rotational speed. The complexity and heterogeneity of the oil film temperature and viscosity reveal the essentiality and significance of the three-dimensional thermohydrodynamic analysis.