Experimental and analytical investigation of fluid drag losses in rolling element bearings

A Four Bearing Test Rig was designed and developed to measure frictional torque of oil lubricated rolling element bearings under various operating conditions. Deep groove ball bearings and radial needle roller bearings were tested for a range of speeds and lubricants. In this investigation, the portion of frictional torque caused by fluid drag losses was determined by analyzing the difference between a fully flooded (submerged) and a minimally lubricated bearing. Ansys Fluent computational fluid dynamics software was used to corroborate and model the different bearing geometries and operating conditions evaluated in the test rig. Drag force of bearing components was calculated from the CFD simulations and compared to the experimental results. The results demonstrate that they are in good agreement. Frictional torque due to fluid drag was further compared to an empirical friction model available in open literature. The CFD model provides a physics-based estimate of fluid drag which corroborates well with the experimental results, while the open literature empirical model tends to over-predict frictional torque from fluid drag. Experimental and analytical results from this investigation suggest that bearing cage design has a small impact on overall fluid drag losses, while substantial improvements can be made by optimizing lubrication conditions and bearing type. The presented CFD model provides an efficient approach to asses fluid drag losses for various bearing geometries and operating conditions.

Automated summary

Experimental and simulation studies have shown that lubrication conditions and bearing types have a significant impact on fluid drag losses, while bearing cage design has a minimal impact on this aspect.