Lubrication, Flow Visualization, and Multiphase CFD Modeling of Ball Bearing Cage

Abstract

The objective of this study was to experimentally and analytically investigate the lubrication condition and visualize the fluid flow in a ball bearing cage under various operating conditions. To achieve the experimental aspects of this investigation, a test apparatus incorporating a transparent cage was designed and developed. The transparent cage was manufactured based on the original geometry of the bearing cage. The transparent cage was positioned in the test rig relative to the ball using a precision XYZ table. This allowed for critical observation and examination of air and oil entrapment conditions within the cage. A high-speed camera was utilized to capture the fluid flow and air distribution inside the cage. To address the analytical aspects of this study, Ansys Fluent computational fluid dynamics (CFD) software was used to develop a multiphase lubrication model simulating the same conditions as the test apparatus. Lubricant and air distribution within the cage were investigated for various operating speeds and cage positions relative to the ball. Results from the experimental and analytical studies were corroborated and found to be in good agreement. The results demonstrate that as the cage was moved closer to the ball, lubrication conditions changed and fluid striated over the ball surface, resulting in greater air entrapment within the cage. The CFD model predicted similar trends and results. Increasing ball speed promoted starvation of lubricant supply to the cage. The CFD model confirmed that lubricant surface tension plays a key role in the striation patterns over the ball surface.