Gearbox Sloshing Effect

Gearbox Sloshing Effect

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. 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\".

Such motion is characterized by \"inertial waves\" and can be an important effect in spinning spacecraft dynamics. Extensive mathematical and empirical relationships have been derived to describe liquid slosh.

3D model as shown below-

2D profile of front view onto this surface-

Case Setup –

Step 1

Fluid volume is extracted from provided 3d model and 2d profile.

Step 2

For meshing the mesh size as 35mm and method applied as triangular method and capture curvature and capture proximity option are marked and number cells is 1.

Step 3

In CFD Tool k-epsilon model with realizable, enable wall method is marked and multi-phase enabled with volume fraction using implied method.

Dynamic meshing parameter are shown-

VALUE ARE INPUT FROM MESH SCALE INFORMATION (after size re-meshing interval)

Time step detail shown –

User defined function is loaded into Ansys

include \"udf.h\"
DEFINE_CG_MOTION(right_motion, dt, vel, omega, time, dtime)
{
	vel[0] = 0.0;
	vel[1] = 0.0;
	vel[2] = 0.0;

LanguageHTML/XML

	omega[0] = 0.0;
	omega[1] = 0.0;
	omega[2] = 2.0e2; /* [rad/s]*/
}
DEFINE_CG_MOTION(left_motion, dt, vel, omega, time, dtime)
{
	vel[0] = 0.0;
	vel[1] = 0.0;
	vel[2] = 0.0;

	omega[0] = 0.0;
	omega[1] = 0.0;
	omega[2] = -2.0e2; /* [rad/s]*/
}

CASE STUDY-

Properties of Oil:

Density: 871 kg/m^3

Viscosity: 0.04006889 kg/m-s

Non clearance model

REGION-(in mm)

Min x- -0.05612 and Max x-0.17112

y- -0.0675 and y- -0.0375

Case 1- Water and Air case

Flow time

Simulation model

Case 2- Oil and Air Case

Flow time

Simulation model

Clearance model

REGION-( in mm)

Min x- 0.12389 and Max x- -0.1678417

y- -02323 and y- -0.04855

Case 3- Water and Air case

Flow time

Simulation model

Case 4- Oil and Air case

Flow time

Simulation model

CONCLUSION-

It is evident from the simulation that oil sticks to gear teeth (more reddish colour in teeth)more than water from that we can conclude that it better to use oil for lubrication process due this higher viscosity of oil.