GEAR SLOSHING EFFECT USING ANSYS FLUENT
AIM:
To perform the simulation for two clearances of the gears and also using a different fluid.
INTRODUCTION:
In fluid dynamicss, slosh refers to the movement of the liquid inside another object theliquid having free surface to constitute a slosh dynamics,where the dynamics of the liquid can interact with the contaiiner to alter the system dynamics significantly.
In given problem, sloshing of gearbox is observed with two different fluids one with more clearence and one with less clearence. lubrication is necessary for safe functioning of the gear. if the gear is not lubricated properly it get weared and it could reduce the life. To see whether the gear teeths are lubricated properly this study is conducted.
A gear is a rotating machine part having cut teeth, which mesh with another toothed part to transmit torque. Geared devices can change speed,torque, and direction of a power source. gears almost always produce a change in torque, creating mechanical advantage, through gear ratio. SPUR GEAR is used in this analysis.
Model of gearbox:
UDF file:
#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;
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]*/
}
Gear with less clearence:
Geometry:
For this simulation the gearbox model is in 3D, the fluid volume is extracted firstly, and from extracted fluid domain 2D model is extracted to simply the model that is as displayed in the below image.
Prepare - Volume extract - selecting edges - extract fluid volume
Design - plane - origin - split body - click object - select
select face for conver it into 2D
Meshing:
Meshing is done using the proximity capture enabled and with selecting the edges of the gear teeth in whole gear for both left and right side of the gear.
Element size = 0.0005m
no of elements = 83462
Setup:
Multiphase - VOF - Implicit
Viscous - Kepsilon - Realizable - Enhanced wall treatment
Transient - Gravity - Y-axis (-9.81)
Material properties - water and air for case1
Phases - phase1 air - phase2 water for case1
Material properties - oil and air for case2
Phases - phase1 air - phase2 water for case2
Adapt - Refine - cellregisters - new region
|
X(min) |
X(max) |
|
-0.05612 |
0.17112 |
|
Y(min) |
Y(max) |
|
-0.0675 |
-0.0375 |
user defined - f(x) - compile - add - open UDF file - Build - Load ( UDF file helps in dynamic motion of the gear)
Dynamic mesh - create/edit - leftside - left motion - rightside - right motion (CG for right motion at x- axis is 0.115)
Solving - Hybrid - Initialize- Patch volume fraction of water (1)
create animation
Time step = 0.0001
Iterations = 826(water) 617(oil)
Scalar Residuals:(Implicit) for water
Scalar Residuals:(Implicit) for oil
Gear sloshing for water: skewness =0.6
This animation shows how the water gets lubricated for the gears with less clearence between the gears in gear box with the working fluid of water inside the given box the sloshing effect is more in using water as fluid because the viscosity is less and sloshing effect is more. using of water as working fluid the lubrication between the gears are low and life is also less for these type of working fluid and the animation shows that the skewness is lesser and with good mesh quality than the higher skewness.
one rotation = 0.0314 rotations
No of rotations as per animation = 2.7633 rotations
Gear sloshing for oil: skewness =0.6
This animation shows how the oil gets lubricated for the gears with less clearence between the gears in gear box with the working fluid of oil inside the given box the sloshing effect is less in using oil as fluid because the viscosity is more and sloshing effect is less. using of oil as working fluid the lubrication between the gears are high and life is also more for these type of working fluid and the animation shows that the skewness is lesser and with good mesh quality than the higher skewness.
one rotation = 0.0314
No of rotations as per animation = 2.056
Gear sloshing for water: skewness =0.8
This animation shows how the water gets lubricated for the gears with less clearence between the gears in gear box with the working fluid of water inside the given box the sloshing effect is more in using water as fluid because the viscosity is less and sloshing effect is more. using of water as working fluid the lubrication between the gears are low and life is also less for these type of working fluid and the animation shows that the skewness is higher and with less mesh quality.
Gear sloshing for oil: skewness =0.8
This animation shows how the oil gets lubricated for the gears with less clearence between the gears in gear box with the working fluid of oil inside the given box the sloshing effect is less in using oil as fluid because the viscosity is more and sloshing effect is less. using of oil as working fluid the lubrication between the gears are high and life is also more for these type of working fluid and the animation shows that the skewness is higher and with less mesh quality.
NOTE:
In less clearence of gears the floating point exemption error with new cell volume detected in dynamic meshing is shown because of remeshing taking place the cells are getting highly skewed finer degree of would require to perfectly setup this simulation considering academic licence the results are shown in the above animations.
Gear with more clearence:
Geometry:
For this simulation the gerbox model is in 3D, the fluid volume is extracted firstly and from extracted fluid domain 2D model is extracted to simply the model that is as displayed in the below image.
Meshing:
Meshing is done using the proximity capture enabled and with selecting the edges of the gear teeth in whole gear for both left and right side of the gear.
Element size = 0.0005m
no of elements = 89584
Setup:
Multiphase - VOF - Implicit
Viscous - Kepsilon - Realizable - Enhanced wall treatment
Transient - Gravity - Y-axis (-9.81)
Material properties - water and air for case1
Phases - phase1 air - phase2 water for case1
Material properties - oil and air for case2
Phases - phase1 air - phase2 water for case2
Adapt - Refine - cellregisters - new region
|
X(min) |
X(max) |
|
-0.13 |
0.17112 |
|
Y(min) |
Y(max) |
|
-0.0675 |
-0.0375 |
user defined - f(x) - compile - add - open UDF file - Build - Load ( UDF file helps in dynamic motion of the gear)
Dynamic mesh - create/edit - leftside - left motion - rightside - right motion (CG for right motion at x- axis is 0.115)
Solving - Hybrid - Initialize- Patch volume fraction of water (1)
Time step = 0.0001
Iterations = 2000(water) 2200(oil)
Gear sloshing for water:(clearence) skewness =0.6
This animation shows how the water gets lubricated for the gears with more clearance between the gears in gear box with the working fluid of water inside the given box the sloshing effect is more in using water as fluid because the viscosity is less and sloshing effect is more. using of water as working fluid the lubrication between the gears are low and life is also less for these type of working fluid.
one rotation = 0.0314
No of rotations as per animation = 6.6 rotations
Gear sloshing for oil:(clearence) skewness =0.6
This animation shows how the oil gets lubricated for the gears with less clearence between the gears in gear box with the working fluid of oil inside the given box the sloshing effect is less in using oil as fluid because the viscosity is more and sloshing effect is less. using of oil as working fluid the lubrication between the gears are high and life is also more for these type of working fluid.
one rotation = 0.0314
No of rotations as per animation = 7.33 rotations
Explanation:
From the above shown animations with two different clearences one with lareger and one with smaller from these gears the oil is lubricating more than the water this means using of oil make the gears lubricated and will be a good life for that gesr than the water. Sloshing of oil is also low compare to water.
The gear teeth occupied with fluid when intersects producing a slosh over the wall case, as the viscosity of the oil is greater than the water the sloshing effect is less in oil and oil for lubricating gears provides smooth friction during motion.
In the animations for less clearence the differnce between the skewness is anlalyes this shows the meshing quality there is lot of deformation in elements when the gear comes into contact while rotating. This is due to skewness value of 0.8 provided which tends to produce poor quality mesh. But in the skewness value of 0.5 provided which tends to better quality than the greater skewness.
Animation:
water:
Oil: