The objective of the research project FVA 857 I "Transmission Oil Flow Simulation" was the development and validation of a simulation methodology for CFD simulation of oil flow and no-load gear power loss in dip-lubricated transmissions and the derivation of a best practice guideline for gearbox oil flow simulation. With the developed simulation methodology, the influence of oil-specific and geometric parameters on oil distribution could be investigated, as exemplified in Figure 1. The simulation results were also used to develop a basic understanding of the interaction of gears with oil and air, where pressure and shear forces were found to be particularly relevant. The oil distribution was found to have a significant influence on the no-load gear power loss. It was also found that the circumferential speed, the direction of rotation and the lubricant viscosity in particular influence the loss torque. Figure 2 shows an example of the simulated oil distribution of a practical gearbox.

In the further project FVA 857 II, the potential of the Smoothed Particle Hydrodynamics (SPH) method for oil flow simulation of practical gearboxes is examined. In future projects, thermal CFD simulations can be used to investigate the heat balance of gears.