Transmissions and axles include gears, bearing and shafts to transmit power from the engine to the wheels. Under stress, these parts can become damaged or degrade in performance due to heat caused by friction. However, as increased amounts of oil are used, the gear churning torque will increase. These churning losses are directly related to loss of power and have a negative impact on fuel efficiency. By modifying the casing, or introducing baffles, oil can be guided to critical regions while decreasing the churning loss.
In test rigs, it is difficult to visualize the flow inside the box for optimizing the flow patterns. Through the use of CFD, the mixture of air and oil can be simulated to improve lubrication systems. In recent years, overset grids with volume of fluid have been introduced in STAR-CCM+® enabling the gear interaction to be modeled easily, while simultaneously modeling fluid interaction with the gears.
This webcast looks at some of the techniques that are being used to simulate gear motion with the oil flow.