Gearbox sloshing effect for different fluids

Gearbox Sloshing Effect

This problem deals with the movement of the the fluid inside a gearbox in real time. The fluid mainly acts a lubricant to reduce the wear and tear of the gear teeth and prolong its life. In this simulation we could see whether all the teeth are properly lubricated and how the circulation of the fluid takes place inside a working gearbox.

Case Setup:

The simulation was carried out for two different geometries with one having normal gear meshing and the other with an additional clearance. To setup a 2D simulation a midplane was obtained of the 3D drawing initially and then it was meshed to have a fine grid size in the vincinity of gear teeth. The Multiphase model was used with Volume of Fraction method and the viscous model used was of Realizable k-epsilon with Enhanced wall treatment. The rotation of gears was obtained by a user defined function and the dynamic mesh option was turned on which enabled the change in mesh pattern as the gears rotate. To visualize the initial condition of water/ oil and air few cells were marked which defined the separation of the two phases.

There are total four cases that were run for this setup-

1. Gearbox with no clearance and water as lubricant
2. Gearbox with no clearance and oil as lubricant
3. Gearbox with clearance and water as lubricant
4. Gearbox with clearance and oil as lubricant

The simulation was carried out using different mesh sizes. However it was observed that for all mesh sizes the result obtained did not show any deviation from one another for that particular case.

For cases 1&2 number of cells marked were 4605 whereas for cases 3&4 7270 cells were marked to define the water/oil phase.

Base mesh

Refined mesh

UDF used for this setup:

Results:

Simulation for Case 1:

Simulation for Case 2:

Simulation for Case 3:

Simulation for Case 4:

Conclusion:

It can be seen from above cases that oil sticks to the gear teeth more for a longer period that the water owing to its viscous properties. Hence Oil is an ideal liquid for a lubricant to reduce the gear teeth wear and tear.