Aspects of flow and cavitation around an EHL contact

This paper focuses on the flow around an elasto-hydrodynamically lubricated ball-on-disc contact. Experiments in the low velocity regime with a small amount of lubricant show two flow states. When the lubricant supply at the inlet side is sufficient, a cavitation bubble is observed at the outlet side of the contact. The bubble length depends on the rolling velocity and the lubricant viscosity. After a sudden stop this bubble breaks up into smaller bubbles that subsequently escape the flooded region. A dimensionless relation is presented that describes the length of the cavitation bubble relative to the contact radius. A theoretical study shows that the length of the bubble cannot be predicted with common EHL models based on a pressure criterion.