Enhanced hydrodynamic lubrication of lightly loaded fluid-film bearings due to the viscosity wedge effect

The paper is a theoretical and experimental research of the viscosity wedge effect in a thin incompressible fluid film. The goal of the theoretical part of the work is a new look on the solution of the Navier-Stokes equation, when the viscosity function is unknown, that allowed to solve an optimization problem and find the optimal viscosity distribution in a fluid-film bearing. The optimal distribution was partially implemented in a test rig with a lightly loaded fluid-film bearing lubricated with mixed hot and cold water. The experimental results correlate with simulation results and demonstrate that the viscosity wedge may have positive effect on decreasing the shaft vibrations and friction coefficient. •It is possible to reduce friction coefficient due to the viscosity wedge effect.•The maximum point of the optimal viscosity distribution in a plain bearing is shifted from the pressure maximum.•The higher the viscosity gradient and the lower the Hersey number, the higher the positive effect of the viscosity wedge.