ANSYS FLUENT - Gearbox Sloshing effect
Aim
To perform the four simulations in the Gearbox for the following cases
- 20% Immersion, Fluid - Engine oil.
- 30% Immersion, Fluid- Engine oil.
- 20% Immersion,Fluid-n-heptane (c7h16).
- 30% Immersion,Fluid-n-heptane (c7h16).
Introduction
In fluid dynamics, slosh refers to the movement of liquid inside another object (which is, typically, also undergoing motion).Strictly speaking, the liquid must have a free surface to constitute a slosh dynamics problem, where the dynamics of the liquid can interact with the container to alter the system dynamics significantly.[1] Important examples include propellant slosh in spacecraft tanks and rockets (especially upper stages), and the free surface effect (cargo slosh) in ships and trucks transporting liquids (for example oil and gasoline). However, it has become common to refer to liquid motion in a completely filled tank, i.e. without a free surface, as "fuel slosh".[not verified in body]Such motion is characterized by "inertial waves" and can be an important effect in spinning spacecraft dynamics.
The sloshing effect of the fluid can also be used to to lubricate the gearboxes. In this experiment we comparing different fluids at different levels of immersions. We are comparing Engine oil & N-heptane(C7H16) and see which lubricates better.
Model
3D model
We cannot use this model because after meshing the cell counts increase & the processing time increase and because we dont have the computer capability its is better to do a 2D simulation. For that we cut the model & copy the 2D model & paste it in a new drawing sheet.
Cut Section
2D
Mesh
Mesh size 0.5mm
Select all triangles mesh for dynamic meshes.
Models Selected
Time - Transient
Enable Gravity = -9.81 m/s2
Solver - Pressure based
2D space - Planar
Viscous model - k-epsilon - Realizable - Enhanced wall treatment
Multiphase - Volume of Fluid(VOF) - Implicit, Phases - phase 1 - air , for phase 2 select oil for the fisrt 2 simulation & N-heptane(C7H16) for the other
Dynamic mesh - Smoothing - Remeshing
Smoothing
Remeshing
Upload the UDF and give appropriate motions to the gears.
Initialize - Hybrid.
Patch - Select the recommended fluid & give the value as 1 for the fluid region.
Results
Oil 20%
Oil 30%
N-heptane(C7H16) 20%
N-heptane(C7H16) 30%
Conclusion
After running the simulation & comparing all the 4 results, N-heptane(C7H16) 30% immersion lubricates the gears better than the other fluid & immersion level.