Behavior of oil droplet swarms during rolling elements-outer ring approach in bearings

The influence mechanism of relative motion between bearing components on inter-component multi-droplet behavior remains unclear. A fractal theory-based simulation model incorporating surface roughness morphology of bearing components was developed. Through experimental validation of the model's accuracy, the study investigates the effects of Weber number and surface roughness on droplet dynamics under relative motion between the outer race and rolling elements. Results show that the wall spreading behavior of oil droplets can be divided into four basic forms: independent spreading, coalescence spreading, impact-film spreading and compression spreading. A method for calculating the contact angle of the oil droplets is presented. Additionally, the expanding and retracting boundaries of moving contact lines during coalescence spreading are analyzed. The evolution of oil droplet surface velocity and contour during impact film spreading are explored. The mechanisms of oil droplet contact line movement during compression and spreading are revealed. Finally, the study reveals the governing laws of Weber number effect on oil droplet coalescence frequency in the far-wall region. The research findings will provide fundamental support for both droplet behavior analysis in microchannels and lubrication efficiency enhancement in bearing systems.