Parametric Study of Gate valve
Aim:
Parametric study of Gate valve
Objectives:
To understand parametric study in Ansys Fluent
To carry out CFD simulation of Gate valve
To obtain the results using parametric study
Introduction:
A gate valve is a valve that opens by lifting a barrier (gate) out of the path of the fluid. Gate valve requires very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened. The gate faces can be parallel but are most commonly wedge-shaped.
Figure: Gate Valve
Gate valves are used to shut off the flow of liquids rather than for flow regulation. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low flow resistance. The size of the open flow path generally varies in a nonlinear manner as the gate is moved. This means that the flow rate does not change evenly with stem travel. Depending on the construction, a partially open gate can vibrate from the fluid flow.
Gate valves are mostly used with larger pipe diameters (from 2" to the largest pipelines) since they are less complex to construct than other types of valves in large sizes.
At high pressures, friction can become a problem. As the gate is pushed against its guiding rail by the pressure of the medium, it becomes harder to operate the valve. Large gate valves are sometimes fitted with a bypass controlled by a smaller valve to be able to reduce the pressure before operating the gate valve itself.
Simulation Procedure:
Step: 1 Geometry Preparation
First of all, the Space-claim is opened and geometry is imported which is in below figure. There various components of gate valve which are also shown in figure.
Figure: Gate Valve
In this step, move option is selected. Then, disc lift is given by movement by component option. Then, Parametric is selected so that we can do parametric study.
Figure: Parametric option
Then, solid volume is increased by using pull tool and then we can extract fluid volume. After keeping all components suppress for physics, gate disc and spindle is kept visual and selected volume as context so that un-necessary parts can be removed.
Figure: Solid bottom extraction
Figure: Fluid Volume
Figure: Cross section of Fluid Volume
Step: 2 Meshing
In the meshing, the name selection of inlet and outlet are given then the meshing of size 0.0055 m is given to model which can be shown in figure.
Figure: Meshing of Gate valve
Step: 3 Set-up
In the set-up, the following parameters are selected.
Solver: Pressure based
Gravity: -9.81 m/s^2 (Z direction)
Model: K-epsilon Realizable
Wall Function: Scalable wall function
Material: Water-liquid
Inlet boundary condition: Pressure based - 10 pa
Outlet boundary condition: Pressure based – 0 Pa
Standard Initialization: from inlet
In this step, when initialization is done then there will be velocity value appears in the Y-direction section which is different for every lift of opening. For 10 mm lift, it 0s 0.14 m/s based on which Reynolds number is calculated and turbulence model is selected. In the report definitions, mass flow rate is selected and create output parameters option is selected. Similarly, Area-Weighted average total pressure at outlet surface is defined.
In the parametric study, calculation is run for one case such as in this study the calculation is run for 10 mm lift of gate disk. Then, close fluent and plot contours as per requirement in CFD-post. After doing these click on the parameter set. It will lead new parameter window where we can define new design point as per requirement. In this, I define design point at every 10 mm between 10 mm to 80 mm. Then, click on Update all design points which will give results of output parameters such as mass flow rate and total pressure at outlet in our case.
Step: 4 Results
The results such mass flow rate at outlet, pressure drop, flow coefficient and flow factor of parametric study of gate valve for 10 mm to 80 mm lift are given below table:
|
Lift (mm) |
Inlet Pressure (Pa) |
Mass Flow rate (kg/s) |
Mass Flow rate (gallons/min) |
total Outlet Pressure (Pa) |
Pressure drop (Pa) |
Pressure drop (Psi) |
Flow coefficient |
Flow factor |
|
10 |
10 |
0.1493 |
2.366405 |
0.1843 |
9.8157 |
0.001423277 |
62.7255 |
54.2575 |
|
20 |
10 |
0.2474 |
3.92129 |
0.2407 |
9.7593 |
0.001415099 |
104.2402 |
90.1678 |
|
30 |
10 |
0.3627 |
5.748795 |
1.0849 |
8.9151 |
0.00129269 |
159.8930 |
138.3075 |
|
40 |
10 |
0.4746 |
7.52241 |
1.8583 |
8.1417 |
0.001180547 |
218.9351 |
189.3788 |
|
50 |
10 |
0.5671 |
8.988535 |
2.6729 |
7.3271 |
0.00106243 |
275.7648 |
238.5365 |
|
60 |
10 |
0.6461 |
10.240685 |
3.4622 |
6.5378 |
0.000947981 |
332.6053 |
287.7036 |
|
70 |
10 |
0.7157 |
11.343845 |
4.2362 |
5.7638 |
0.000835751 |
392.3935 |
339.4203 |
|
80 |
10 |
0.785 |
12.44225 |
5.0961 |
4.9039 |
0.000711066 |
466.5993 |
403.6084 |
Figure: Mass flow rate vs lift
Figure: Pressure drop vs lift
Figure: Flow coefficient and Flow factor vs lift
From above graph, we can see that if lift increases then mass flow rate increases and decreases the pressure drop in gate valve. The flow factor and flow coefficient will also increases with increase in lift of disk.
Contours:
Lift 20 mm:
Streamline Animation video:
https://drive.google.com/file/d/1Z_N7FHXck5FhzTS_a_2wQisG-GIKerxW/view?usp=sharing
https://drive.google.com/file/d/1eFGHucFOSm_rarjkr5T2bqGIteOo688N/view?usp=sharing
Velocity contour:
Pressure contour:
Lift 50 mm:
Streamline Animation video:
https://drive.google.com/file/d/1Gibz8K6cqoPuS506L727cWPtbMQHDtlV/view?usp=sharing
https://drive.google.com/file/d/1NkkvLp2RU6_J8txAcfdf89QoBC117wtR/view?usp=sharing
Velocity contour:
Pressure contour:
Conclusion:
Gate valve is one type of the flow controlling device which controls flow of fluid passing through it. The disk in gate valve plays most important role which control flow by lift motion. As the lift increases then it will increase mass flow and decreases the pressure drop. Flow coefficient and flow factor also increases with increase in lift of disk.