Research

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This study investigated the influence of cage geometry on lubricant flow and drag losses in deep groove ball bearings (DGBBs). A CFD model was developed to simulate the lubricant flow within a DGBB. The design of experiments (DOE) approach was utilized to systematically assess the impact of key cage design parameters (i.e. pocket height, bridge height and bridge depth) on lubricant flow behavior and drag losses. Leveraging the DOE results, a regression model was developed to establish the relationship between the drag coefficient and modified Reynolds number as a function of the cage design factors. Learn more.

The aim of this study is to investigate the initiation and motion of aerated bubbles within lubricating oil.  To facilitate in situ observation of the aerated bubbles in the lubricating oil as well as starvation in bearings, transparent acrylic cage and outer race were used in the Counter Rotating Angular Contact ball bearing Test Rig (CRACTR).  Additionally, a novel multiphase computational fluid dynamics (CFD) model is developed to simulate the intricate flow dynamics of aerated bubbles within the lubricating oil and to gain comprehensive insights into their origination.  The model employed a coupled solver featuring a two-way transition algorithm between the Discrete Phase Model (DPM) and the Volume of Fluid (VOF) approach.

This study experimentally investigates lubrication between cam-roller follower and roller-pin contact. In order to experimentally study the lubrication, a section of a heavy-duty diesel engine valve train was used to develop a valve train test rig (VTTR). A high-speed camera was utilized to capture the in-situ lubricant flow between cam-roller follower and roller-pin. The steel roller in the rocker arm was replaced with a transparent sapphire roller to visualize the oil flow between the roller and pin. The experimental results showed lubricant starvation between the cam – roller follower gap and the effect of cavitation between roller – pin contact. Wear marks were observed on the pin due to the effect of cavitation. 

The objective of this study was to develop a numerical model for Aerodynamic Leidenfrost Effect (ALE) to simulate the levitation of a lubricant drop near a surface with high speed. In this model, the oil droplet is treated as a deformable soft elastic body, whose weight is supported by the air film lubrication pressure. The Young's Modulus of the oil droplet is represented by its internal pressure and surface tension. In this modeling approach, the two-dimensional compressible Reynolds equation for air and elasticity equations were discretized and numerically solved using the finite difference approach. Learn more.

This study experimentally investigated the phenomenon of lubricant condition on bearing surfaces under high-speed conditions. The primary tests were conducted using high-speed rotating ball, inner race and outer race setups. The experimental results revealed that as the speed increases, the Aerodynamic Leidenfrost Effect (ALE) becomes significant, which inhibits lubricant adhesion to the bearing surfaces. The influence of lubricant properties was investigated by testing with lubricants of varying viscosities, while the effect of surface finish was examined by comparing coatings with different wettability characteristics. Learn more.

This investigation presented new experimental and analytical findings for oil starvation inside different ACBB cages for a variety of test conditions. Oil–air regions were identified inside ACBB cages using high-speed videography and UV lights. The results of the experimental measurements were consistent with the two-phase CFD model and provide valuable information to improve bearing cage designs. Learn more.

The objectives of this investigation were to experimentally and analytically study the oil flow inside an angular contact ball bearing using an innovative visualization technique of Bubble Image Velocimetry (BIV) and CFD Modeling. The quantitative and qualitative validation of CFD results provides a basis for cage design for efficient lubricant flow inside a bearing. Learn more.

The objectives of this investigation were to experimentally examine the cage motion and ball-cage contact forces for an angular contact ball bearing (ACBB) operating under various load and speed combinations. In order to achieve the objectives, a Counter Rotating Angular Contact Ball Bearing Test Rig (CRACTR) was designed and developed such that both the races of an ACBB can be rotated simultaneously in opposite directions, providing valuable insights into the ball-cage interaction. Learn more.

This work was focused on the design and development of a novel experimental test rig for the investigation of friction between a ball and cage of a deep groove ball bearing. The experimental apparatus was designed and developed to replicate the orientation and dynamics of a full bearing in steady-state operation while collecting measurements of cage friction. A six-axis load cell was used to record force and torque values generated due to a rotating ball inside of a rigidly fastened cage segment. Learn more.