Abstract
Mineral or synthetic oils and greases are typically used to lubricate mechanical components, which would otherwise suffer from premature wear. While the lubricants impede the direct contact between surfaces reducing the friction, their presence and interaction with moving parts implies additional power dissipation (churning). Most of the analyses in literature have been performed with oil as lubricant, while grease was poorly touched both experimentally and numerically. Being grease a non-Newtonian fluid, density and viscosity are not enough to describe the fluid behavior, and additional properties are necessary to fully define these kinds of fluids. In this work, the churning phenomena related to grease lubrication are investigated on a back-to-back test rig equipped with two gearboxes exploiting Computational Fluid Dynamics (CFD). The grease distribution as well as the power dissipation are analyzed numerically. The results in terms of lubricant distribution and power losses are compared with oil as lubricant cases. A highly efficient mesh handling strategy was used to simulate the gearbox, making it possible to drastically reduce the computational effort of the simulations, thus opening new scenarios for a massive introduction of CFD applied to lubrication also in industry.