International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
J. V. Bhanutej
1
, S. Phani Kumar
2
B. Pradeep Kumar
3
1
Assistant professor, Department of Mechanical Engineering.ANITS.
2
Assistant professor Department of Mechanical Engineering.ANITS,
3
Assistant professor Department of Mechanical Engineering.ANITS.
ABSTRACT
In India, agriculture has a predominant role in our day to day life. The crops that come as yield decides the total production, adds to the economy of our country. The yield decreases due to the presence of pests, insects in the farms. To kill the pests, insect’s pesticides, fertilizers are sprayed either manually or by using sprayers. Earlier, the pesticides and fertilizers were sprinkled manually, but they will result in harmful effects on farmers. In order to overcome this problem, Different spraying techniques have been developed.
These sprayers consist of different mechanisms and the cost of equipment is generally high. We developed a mechanism in which we tried to minimize the equipment cost by removing the pump to spray. This Sprayer works on Bernoulli’s principle, in which the spraying action of the sprayer is due to the head developed and mechanical linkage. The model is developed mathematically for the major components like tank, required head and the spring mechanism. Later the model of sprayer tank is developed in the AUTODESK
INVENTOR software. This model is simulated for dynamic characteristics of spring. The tank model is developed in the
Ansys Workbench and analyzed for stress developed due to hydro static pressure. We also studied the spray pattern using
ANSYS CFX solver with a mean droplet diameter of 50 microns. The Von-Mises stress of the tank is analyzed for the safe hydro static pressure for two different materials structural steel and polyethylene. Polyethylene is chosen as best. The minimum torque required to overcome the maximum spring load is tested for various time steps by giving a constant torque to the mechanism.
Keywords — Ansys CFX, Autodesk Inventor, Polyethylene,
Sprayer .
stored in the tank and additional spring force is used for generating the required velocity during spraying. The design includes stress analysis of the tank, study of spray pattern of jet and determination of minimum torque on the lever to operate the spring. Different software packages like Autodesk Inventor Professional, Ansys were used for design and analysis .
In the previous work [1],[2] the spray will be obtained by reciprocating pump mechanism which will be driven by wheel of the vehicle. In the second work the spray will be obtained by reciprocating pump which is driven by vehicle which is operated by fuel. In the present model the spray will be obtained due to the head of the fluid and spring force.
The sprayer design is done by assuming the spray distance.
It is assumed that the range of jet is 2 m. By assuming this condition the velocity of jet at exit of the pipe nozzle has been calculated.
2.1 Jet calculations:
The potential energy due to the head of the water in the tank is
H
1
2
2
1
1
2
2
2 t 2
9.81
t 0.45s
A sprayer is a device used to spray a liquid.
In agriculture, a sprayer is a piece of equipment that is used to apply herbicides, pesticides, and fertilizers on agricultural crops. Sprayers range in size from manportable units (typically backpacks with spray guns) to trailed sprayers that are connected to a tractor, to selfpropelled units similar to tractors, with boom mounts of
60–151 feet in length. Timely application of herbicides pesticides and fungicides at peak periods plays a vital role in ensuring better yields from a crop.
The scope of the project is to develop a new mechanism for spraying of pesticides. The mechanism is designed such that the potential energy of the pesticide
Range R . m
Assuming Range of j et, R 2 m
2 u
0.45
u 4.43 m s
2.2 Force calculations:
The tank is assumed to be situated at a height of
2m and bottom of pipe at 1m from the ground as shown in figure 1. By using the Bernoulli’s principle for this setup the minimum force required at the bottom of the sprayer tank to maintain the spray range.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015 applying Bernoulis therom, p
1 v
1
2 g 2 g z
1 p
2 v
2
2 g 2 g z
2 variable p
1 p
2 v
1 v
2 z
1 z
2
H
R
F h*
M
Figure 1: Setup of the Sprayer tank
TABLE I
NOMENCLATURE
Description
Pressure at inlet (N/m
2
)
Pressure at outlet (N/m
2
)
Velocity at inlet (m/s)
Velocity at outlet (m/s)
Potential head inlet (m)
Potential head at outlet (m)
Height of the pipe from the ground (m)
Range of spray from pipe (m)
Force acting on the side walls (N)
Distance at which total pressure force is acting (mm)
Moment about bottom of the tank (N-m)
Bending stress of the wall (N/m
2
) y
I’ t
1
' t
2 distance of neutral axis (mm)
Moment of inertia about centroidal axis (mm
4
)
Yeild strength of the material (N/m
2
)
Thickness of structural steel tank (mm)
Thickness of polyethylene tank (mm) v
1 v
2 p
1 p
2 pressure at section 1 pressure at section 2 velocity at section 1 velocity at section 2
1
1
2
2 z
1 potential head at section 1 1 z = potential head at section 2 2
Section (2)-(2) is taken as reference. Z
2
=0 m
The losses in the pipe are taken as 10% p
1 v
2
1 g 2 g z
1 p
2 v g 2
2
2 g
0.1
p
2 g
0 m
(as it is at atmospheric pressure)
2 p
1 1
4.43
0.1
g 2 9.81
p
1 g
0.1002 m p
1
9810 0.1002
p
1
982.96 N/m
2
Assuming the tank cross-sectional area as 0.5 0.3 m force acting on fluid surface F p
1
A
=982.96 0.5 0.3
2.2 Tank calculations:
The tank should be able to resist the forces due to pressure and load acting on it, so the thickness of the tank has been calculated by taking the tank material as structural steel.
F gAh PA
Figure 2: Hydrostatic pressure acting on the tank side plate
The force acting on the side wall F
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
The distance at which force is acting is h* 1. Part designing
2. Assembly I h * h
A h
Distance from the bottom of the tank X
X - *
Moment about the bottom edge M
M F X
For calculating the thickness bending stress of the tank is calculated
=
My
I '
Here,
3.1 Part designing:
In this stage different parts of the sprayer tank are designed with the required dimensions.
Different parts of the sprayer tank are designed as follows:
1.
Tank
2.
Lower plate
3.
Upper plate
4.
Slider shaft
5.
Fork (used as connecting rod)
6.
Crank disk
7.
Handler
8.
Bracket
9.
Compression spring t y
2
I'= b t 3
12 b =500 mm
The 3D model is created, by using various modeling operations like extrude, sweep, revolve, etc.
Bending stress of the wall =
'
.
2
By substituting these values we will get the thickness of the tank wall as, t = 1.5 mm.
Adding corrosion allowances as 2 mm, the designed thickness for the structural steel tank is t
1
= 3.5 mm
If we change the tank material to polyethylene with yield strength '= 25 N/mm
2
, then its thickness t
2 is
3.4mm, there will be no corrosion allowances since it is plastic.
By taking above two thickness values into consideration we have designed and modeled a tank of thickness t=3.5mm
The model of the sprayer tank has been designed using Autodesk Inventor software. The design of the model has been done in two different stages.
Figure 3: Various parts of sprayer tank
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
3.2 Assembly:
In assembly modeling, we combine parts and subassemblies to form an assembly that functions as a single unit. Parts and subassemblies are connected to one another by assembly relationships. Relationships control component placement and Degrees of Freedom (DOF). we can edit individual parts or the entire assembly. We can also define a set of features in the assembly that interact with multiple parts.
Figure 5: Spring before compression
Figure 4: Assembled model of sprayer tank
3.3 Dynamic simulation of sprayer tank.
The dynamic simulation is done for the assembly model with input load as linearly varying torque at the disc. The input grapher is shown in the graph 1. The spring compression before and after the simulation are given in the figure 5 and 6. The model is also checked for DOF, 4 mobile bodies are present without any redundancy.
ISSN: 2231-5381
Figure 6 : Spring after compression
The sprayer tank is analyzed for the von-Mises stress for the hydrostatic load acting on it. Initially in the
Ansys workbench the static structural analysis module is selected for the analysis.
Steps involved in tank analysis are
Step 1: Engineering data
In this step material is be selected and that should be applied to the model. We have added two different materials i.e. structural steel and Polyethylene to compare the results.
Material Assignment: Polyethylene, Structural steel
Step 2: Geometry
The tank is designed for the design dimensions in the design modeler. By using the standard box primitive and shell command the model is generated.
Step 3: Meshing
The model that is created in the geometry is then meshed using fine triangular mesh and it be generated. http://www.ijettjournal.org
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
This mesh makes the whole material into fine elements by which it is easy for calculating displacement function.
To generate spray, the nozzle and the bounding volume for the atmosphere is modeled in the Ansys design
Mesh details:
Nodes
Elements
30357
14928 modeler. Atmospheric model length is taken cylindrical volume with radius 150 mm and height 1000 mm. The nozzle outlet diameter is assumed as 5 mm
Figure 8 : Meshing of tank
Step 4: Setup
After giving the mesh to the model, it is made for set up. In the setup the fixed support to the model is given as bottom surface of the tank. Then hydrostatic load and a spring force as remote force is applied to the model on the four side walls and on the bottom wall. These two forces are applied at a distance of 200mm from the top since no force is acting at top.
Figure 9 : Geometry of Nozzle
Step 2: Mesh
The model is meshed for Hex Dominant method for better results. The named selection for atmospheric inlet and outlet is created for easy identification in the
CFX environment. The mesh data is given below
Nodes
Elements
40694
47541
Mesh Method Hex Dominant
Free Face Mesh Type Quad/Tri
Figure 7: Load Setup of Tank
Step 5: Solution
The model is then evaluated for the solution after giving displacement and the forces. The required results are selected before solving i.e. Total deformation and von-
Mises stress.
Step 6: Results
Once the solution is evaluated then total deformation and von-Mises stresses will be checked out for tank.
The spray is generated in ANSYS CFX solver and the characteristics of the generated spray are studied from the results. In the ANSYS
The analysis involves the following steps
Step 1: Model
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Figure 10 : Meshing of Nozzle
Step 3: Setup
The initial conditions must be specified CFX pre setup to generate the spray. Transient Analysis type is selected for 10 s at time step of 0.05s. Inlet, wall and atmosphere boundary conditions are created. The initial velocity at nozzle for water is taken as 4.43 m/s, which obtained from the design calculations. Water and air material models are created and for water dispersed model is considered for spray at mean diameter of the droplet as
50 microns. At inlet the water volume fraction is taken as 1 and the 0 for air. At atmosphere for water volume fraction is 0 and air volume fraction as 1. Form output controls the standard results requirement is created as transient results.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015 pressure and maximum spring load. The results from the finite element analysis for two different materials - structural steel and Polyethylene are tabulated in TABLE
II. and the render files are shown in figures 12 to 15. From the results it has been concluded that polyethylene is suitable than structural steel since it is a light weight material.
Figure 11: Setup of the Nozzle
Setp4: Solution
The setup that is already done in the earlier step is solved by using start run for the results to be obtained in the CFX solver manger.
Setp5: Results
The water volume fraction, water velocity of the generated spray is studied from the results.
Material
TABLE II
COMPARISON OF RESULTS
Structural steel Polyethylene
Minimum
Maximum
Von-Mises stress
MPa
Total deformation
in mm
Von-Mises stress
MPa
8.06e-4
2.0403
0
2.49e-2
3.165e-4
1.9266
Total deformation in mm
0
4.076
6.1 Dynamic simulation of the agriculture sprayer tank assembly
The dynamic analysis is performed on the sprayer tank to evaluate the degrees of freedom of the assembly.
The minimum torque required at the disk to overcome the spring load is obtained by applying linearly varying torque from 0 to 30000 N mm for 100 s. The spring compression at that time is shown graph 1. From this, to rotate the disk into 180
0
the minimum torque required in constantly increasing torque case is at time step 84 s and minimum torque as 25200 N mm.
Figure 12: Equivalent (von-Mises) Stress in Structural
Steel tank
Figure 13: Total deformation in the Structural Steel tank
Graph 1: Variation of deflection of spring with time
6.2 Finite Element Analysis Of Tank
The sprayer tank is analyzed for Von-Mises stress and deflection due to combined load of hydrostatic
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
Figure 14: Equivalent(von-Mises) stress in
Polyethylene tank
Figure 16: Volume rendering of Water velocity from nozzle outlet
Figure 17: Water velocity from nozzle outlet in plane YZ
Figure 15: Total Deformation in Polyethylene tank
6.3 Spray from nozzle:
The spray is generated in the CFX solver by taking the calculated velocity at the nozzle outlet, and 50 microns water droplet dispersed model is used. The characteristics of the spray water droplets are studied through this analysis and the results are viewed in CFD post. In this, a plane is created in YZ direction at the center of nozzle and, nine intermediate planes are created in XY direction between the nozzle and atmosphere opening boundary, each 100 mm apart. On these planes water velocity and water volume fractions are studied .
The volume rendering of the spray for water velocity and water volume fractions are shown in figures
16 and 17. The water velocity and water volume fraction of spray in YZ plane are shown the figures 18 and 19. The maximum values of water velocity and water volume fraction at intermediate planes are tabulated in TABLE III,
The corresponding images are shown in figures 20 and 21., and the graphs are plotted for distance from nozzle outlet and water velocity, distance from nozzle and water volume fraction in the graphs 2 and 3.
Figure 18: Volume rendering of Water volume fraction from nozzle outlet
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015
Graph 2: Water velocity v s
distance from nozzle outlet
Figure 19: Water volume fraction from nozzle outlet in plane YZ
6
7
8
9
2
3
4
5
The variation between the distance from nozzle outlet, maximum velocity and maximum water volume fraction are observed in intermediate XY planes. The maximum water velocity is decreasing, with increase in distance from nozzle outlet, which can be clearly shown in the figure 20. Also the maximum water volume fraction is decreasing with increase in distance from nozzle outlet, which can be clearly shown in the figure 21.
TABLE III
Maximum Velocity And Water Volume Fraction Varying With Distance
From Nozzle Outlet
S.
No
Distance from nozzle outlet z mm
Maximum
Velocity (m/s)
Maximum Water
Volume Fraction
1 0 4.43 1
10
100
200
300
400
500
600
700
800
900
4.32
4.28
4.2
3.94
3.62
3.27
2.95
2.56
2.24
0.0849
0.0663
0.0628
0.0578
0.0562
0.0554
0.0546
0.0556
0.0554
Figure 20: water velocity in XY planes
Graph 3 Water volume fraction v s
distance from nozzle outlet
Figure 21: water volume fraction in XY planes
7.1 Conclusion
In this project the Von-Mises stresses is analyzed for structural steel tank and polyethylene tank. The spring
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International Journal of Engineering Trends and Technology (IJETT) – Volume 23 Number 6 - May 2015 load is tested for various time steps by giving a constant torque input to the mechanism. The spray characteristics of Applied Research and Studies (iJARS), ISSN: 2278-
94980 Volume 2, Issue 11(Nov-2013) observed by dispersed fluid analysis in CFX solver with droplet diameter of 50 microns.
1) The Von-Misesstress of the tank for the given hydrostatic pressure and the maximum spring load is evaluated for both structural steel and polyethylene.It is observed that the von-Mises stress is nearly same for both, but the deformation of polyethylene tank is more, which is acceptable. So the polyethylene material is best suited for tank design as it has very less weight compared to structural steel.
2) The dynamic simulation of the mechanism gives the minimum torque to overcome the maximum spring load as 25200N mm.
3) From the graphs 7.2 and 7.3 it is observed that the water velocity and water volume fraction is reducing, as the distance of spray particles from the nozzle outlet is increasing. Also the water velocity is
2.24 m/s at 900 mm distance away from the nozzle outlet and the spray is dispersed with a volume fraction of 0.0554. From these observations we can conclude that the spray coming out of the nozzle for the designed velocity shows well dispersion, which is required for agricultural sprayer.
[3] R. Joshua, V. Vasu and P. Vincent “Solar Sprayer -
An Agriculture Implement”, “International Journal of
Sustainable Agriculture 2 (1): 16-19, 2010 ISSN 2079-
2107”
[4] Design of Water Tank by Dr. G.S.Suresh, Professor,
NIE, Mysore.
[5] Nozzles: Selection and Sizing Virginia Cooperative
Extension Publication442- 032.
7.2 Future Scope
Tank thickness is calculated by taking corrosion into consideration, which leads to high safety factor to the tank, is not necessary. Assuming use of protective coatings, the same tank can be optimized for minimum thickness to reduce the weight.
Dynamic analysis of the tank can be performed to determine stresses induce in the spring for the maximum and minimum spring load
Computational fluid dynamics of this system can be done to determine the pipe losses.
By taking the joint loads from the dynamic simulation the pins and other components in the sprayer tank can be designed
Spray analysis can be carried out for various droplet sizes.
[1] Development Of Wheel Driven Sprayer,
1
Shivaraja kumar. A,
2
Parameswaramurthy. D, International journal of engineering Research-Online Vol.2., Issue., 2014 ISSN:
2321-7758
[2] Design, development and fabrication of agricultural pesticides sprayer with weeder,
1
Laukik P. Raut
*
,
Smith B. Jaiswal,
3
Nitin y. Mohite,International Journal
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