Simulation of Gearbox Sloshing effect

Sloshing is a complex phenomenon caused by the movement of a liquid inside an object. Sloshing occurs when lubricating automotive parts and during vehicular motion in fuel tank. The sloshing property of a liquid influences how it lubricates the parts of a vehicle, noise generation and also dynamic pressure acting inside that object. In this project concentration is given on how shoshing property of a liquid affects part lubrication of gears in a gearbox.

Since there is a limitation to the number of elements that can be simulated in ANSYS academic licence only 2D gearbox is considered for simulation. For this study two liquids are considered, which are water and oil. The oil considered here has the a density of 871 kg/m^3 and a viscosity of 0.04006889 kg/m-s. All triangular meshing method is used with the element size for all four cases is taken as 30mm with capture proximity turned on taking number of cells across gap as 3. A transient simulation is run for two cases of clearances for both the liquids. To simulate a more realistic condition gravity is considered acting along y-axis with a value of -9.81m/s^2. A movement of 200 rad/s is given to the gears for this simulation. A dynamic meshing technique is used to capture movement of a gears inside the gearbox by employing a UDF with local cell remeshing conditions taken as follows: 0.0001m for maximum length scale, 0.002m minimum length scale, 0.7 for maximum cell skewness and size remeshing interval taken as 2. A realizable k-`epsilon`model with enchanced wall treatment is considered for turbulence modelling and implicit volume of fluid method is used for multiphase modelling. Initially a region in the lower parts of the gearbox is marked and patched to volume fraction of 1 of the considered liquid. A time step of 0.0001s is used and the number of time steps is taken as 1322 for all 4 cases i.e., the case is simulated for 0.1322s. The animation is captured for every time step.

Geometry with less clearance:

Mesh for the geometry with less clearance:

Geometry with more clearance:

Mesh for the geometry with more clearance:

Since water has low viscocity it gets sloshed everywhere easily unlike oil which has high viscocity. The oil tries to band together instead of getting sloshed and that is why it is difficult to lubricate all of areas and components with oil. The comparison is made just to study/observe how sloshing takes place with oil in comparison to water but water is never used for lubrication because of its poor lubrication properties.