ELASTOHYDRODYNAMIC LUBRICATION WITH WATER-IN-OIL EMULSIONS

Although water-in-oil (W/O) emulsions have higher viscosity than the b ase oils, they often form thinner elastohydrodynamic films than those formed with the base oils alone. This unreasonable behavior of W/O emu lsions is studied experimentally and analytically. First, atmospheric and high-pressure viscosities of W/O emulsions are measured in a rolli ng-sphere viscometer. Secondly, the minimum thickness of their elastoh ydrodynamic films in line contact is determined with an X-ray transmis sion technique. Then a two-phase hydrodynamic film model is proposed, and Patir-Cheng's average flow concept is employed to calculate the eq uivalent viscosity of the films. Finally, a full elastohydrodynamic so lution is obtained by using a multigrid technique.