A novel model for a mixed-film lubrication with oil-in-water emulsions

• A mixed-film model with two adsorbed layers and an emulsion layer is proposed.
• The adsorbed thickness of the upper and lower surfaces vary with the x-axis.
• The adsorbed thickness at the entrance can be successfully predicted.
• The adsorbed layers can merge to form an oil pool at the low speed region.
• The average oil concentration in the inlet zone decreases with increasing speed.

A mixed-film model with two adsorbed layers on the solid surfaces and an emulsion layer between them is proposed to explain the lubrication mechanism of oil-in-water emulsions. The effects of the adsorbed layer thickness at the entrance, the supply oil concentration, and the rolling speed on the central film thickness of the EHL line contact are investigated. Compared with the experimental results, the adsorbed thickness at the entrance remains constant for different supply oil concentrations at high rolling speeds, but it increases with decreasing rolling speed at low and intermediate speeds, because there is enough time to replenish the adsorbed film.