An investigation into the thermal mixing in journal bearings

Abstract Flows in the thermal mixing zone of a journal bearing are investigated using the computational fluid dynamics (CFD) approach. The complexity and inertial effect of the flows inside the supply region of different configurations are considered. It is shown that these flows are highly recirculating but have almost negligible effects on the thermal mixing. The turbulent flow inside the supply region is modelled using the k-ω turbulence model. Most parts of the supply region are filled with recirculation zones and most of the injected cold oil does not immediately enter the oil film. For all configurations considered the extent of the thermal mixing zone is not confined to just above the supply groove. This zone extends some distance beyond the pockets/grooves and in some cases extends for almost the whole bearing length in the axial direction. The length of the supply region and supply pressure governs the extent of the mixing zones. To investigate the effect of various groove dimensions, locations and bearing operating conditions on the bush temperature, the supply region and oil film were considered as separate domains. This allows the difference in length scales to be resolved. The results are presented quantitatively in terms of bush temperatures and maximum temperature. A flow field inside a pocket is compared with available experimental flow visualizations.