Parametric Study on a Gate Valve by Varying the Gate Valve Opening
Objective: Perform Parametric Study on a Gate Valve by Varying the Gate Valve Opening using Ansys Fluent and write a detailed report explaining the results obtained.
Question:
For this challenge, you will have to perform a parametric study on the gate valve simulation by setting the opening from 10 % to 80%.
- Obtain the mass flow rates at the outlet for each design point.
- Calculate the flow coefficient and flow factor for each opening and plot the graph.
- Discuss the results of the mass flow rate and flow coefficient.
From above information, the following cases can be analysed for expected results.
- DP0: Lift - 10mm
- DP1: Lift - 20mm
- DP2: Lift - 30mm
- DP3: Lift - 40mm
- DP4: Lift - 50mm
- DP5: Lift - 60mm
- DP6: Lift - 70mm
- DP7: Lift - 80mm
- DP8: Lift - 90mm
Gate Valve:
A gate valve, also known as a sluice valve, is a valve that opens by lifting a barrier (gate) out of the path of the fluid. Gate valves require very little space along the pipe axis and hardly restrict the flow of fluid when the gate is fully opened.
Gate valves are widely used for all types of applications and are suitable for both above-ground and underground installation. Not least for underground installations it is paramount to choose the right type of valve to avoid high replacement costs.
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.
Case Setup and Execution:
Geometry:
Geometry is imported to Ansys Space Claim.
The flow volume is increased by pulling the pipe’s outer solid surface by 800mm from both the sides before extracting the fluid volume.
Extract of the volume domain of the main body by using the Volume extract command.
Lift the disc in +Y direction by selecting the move command and opt for parametric study.
Select the volume and click on 'Update volume body in context'. This is done to change the volume of the fluid according to the lift provided in parametric study.
Meshing:
Element size: Default (92.8mm)
Nodes: 29084
Elements: 137418
Named Selections:
Setup:
Solver: Pressure Based
Time: Steady
Gravity is enabled and enter the z direction valve as a -9.81 m/sec^2.
Models: k-epsilon Realizable Model with Scalable wall functions
Material: Water for volume.
Boundary Conditions:
Inlet - Pressure inlet with Gauge pressure as 10 Pa.
Report Definitions:
Mass Flowrate for output and opted for 'create output parameter' for parametric study.
Total Pressure for output and opted for 'create output parameter' for parametric study.
Standard Initialization is done.
Solution is run for 500 iterations.
Parametric Study is done for all design points.
| # | P3 - Group1 [mm] | P4 - mass-flow-outlet-op [kg s^-1] | P5 - pressure-outlet-op [Pa] |
| Name | P3 | P4 | P5 |
| DP 0 | 10 | -0.14873167 | 0.18862892 |
| DP 1 | 20 | -0.23853659 | 0.48518572 |
| DP 2 | 30 | -0.36444551 | 1.1252746 |
| DP 3 | 40 | -0.46885516 | 1.8684878 |
| DP 4 | 50 | -0.5531507 | 2.6194159 |
| DP 5 | 60 | -0.63430906 | 3.4179608 |
| DP 6 | 70 | -0.70942099 | 4.3173038 |
| DP 7 | 80 | -0.765659395 | 5.0590679 |
| DP 8 | 90 | -0.8218978 | 5.800832 |
The negative sign for the Mass flow rate is due to the fluid flow out of the Gate valve, so we consider it as positive valve for further calculations.
Results:
DP0: Lift - 10mm
Residuals:
Velocity Contour:
DP1: Lift - 20mm
Residuals:
Velocity Contour:
DP2: Lift - 30mm
Residuals:
Velocity Contour:
DP3: Lift - 40mm
Residuals:
Velocity Contour:
DP4: Lift - 50mm
Residuals:
Velocity Contour:
DP5: Lift - 60mm
Residuals:
Velocity Contour:
DP6: Lift - 70mm
Residuals:
Velocity Contour:
DP7: Lift - 80mm
Residuals:
Velocity Contour:
DP8: Lift - 90mm
Residuals:
Velocity Contour:
Calculate the flow coefficient and flow factor for each opening and plot the graph.
Flow Coefficient:
The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate.
Mathematically the flow coefficient Cv (or flow-capacity rating of valve) can be expressed as:
where:
- Q is the rate of flow (expressed in US gallons per minute),
- SG is the specific gravity of the fluid (for water = 1),
- ΔP is the pressure drop across the valve (expressed in psi).
Flow Factor:
The metric equivalent flow factor (Kv) is calculated using metric units :
where
- Kv is the flow factor
- Q is the flowrate
, - SG is the specific gravity of the fluid (for water = 1),
- ∆P is the differential pressure across the device (expressed in [bar]).
Kv can be calculated from Cv using the equation:
| # | P3 - Group1 [mm] | P4 - mass-flow-outlet-op [kg s^-1] | Volume Flow Rate [m^3/sec) | Volume Flow Rate [gallons/min) | P5 - pressure-outlet-op [Pa] | Pressure at inlet [Pa] | Pressure Diff [Pa] | Pressure Diff [Psi] | specific gravity of water | Flow Coefficient | Flow Factor [m^3.h^-1. bar^-0.5] |
| Name | P3 | P4 | * | * | P5 | * | * | * | * | * | * |
| DP 0 | 10 | 0.14873167 | 0.00014899987 | 2.36169263946 | 0.18862892 | 10 | 9.811371 | 0.001423022 | 1 | 62.6062403 | 54.15439788 |
| DP 1 | 20 | 0.23853659 | 0.00023896673 | 3.78769436052 | 0.48518572 | 10 | 9.514814 | 0.00138001 | 1 | 101.960949 | 88.19622073 |
| DP 2 | 30 | 0.36444551 | 0.00036510270 | 5.78698724656 | 1.1252746 | 10 | 8.874725 | 0.001287172 | 1 | 161.299924 | 139.524434 |
| DP 3 | 40 | 0.46885516 | 0.00046970062 | 7.44489575304 | 1.8684878 | 10 | 8.131512 | 0.001179378 | 1 | 216.786414 | 187.5202478 |
| DP 4 | 50 | 0.5531507 | 0.00055414817 | 8.78341469140 | 2.6194159 | 10 | 7.380584 | 0.001070465 | 1 | 268.458476 | 232.2165814 |
| DP 5 | 60 | 0.63430906 | 0.00063545288 | 10.07211870461 | 3.4179608 | 10 | 6.582039 | 0.000954646 | 1 | 325.986565 | 281.978379 |
| DP 6 | 70 | 0.70942099 | 0.00071070025 | 11.26481217258 | 4.3173038 | 10 | 5.682696 | 0.000824207 | 1 | 392.37907 | 339.407896 |
| DP 7 | 80 | 0.765659395 | 0.00076704007 | 12.15781517397 | 5.0590679 | 10 | 4.940932 | 0.000716623 | 1 | 454.161372 | 392.8495864 |
| DP 8 | 90 | 0.8218978 | 0.00082337988 | 13.05081817537 | 5.800832 | 10 | 4.199168 | 0.000609039 | 1 | 528.828939 | 457.4370321 |
Conclusion:
- The negative sign for the Mass flow rate is due to the fluid flow out of the Gate valve.
- The Mass flow rate and total pressure at outlet increases with an increses of the lift dimensions or Lift opening.
- The pressure difference decreases with an increase in lift opening.
- The mass flow rate is depends only the opening of the Gate valve.
- The Flow coefficient and Flow Factor increases with an increase in lift opening, as it depends on mass flow rate value.