Week 9 - Parametric study on Gate valve.
GATE VALVE SIMULATION:
Theory:
Gate valves work by inserting a rectangular gate or wedge into the path of a flowing fluid. They are operated by a threaded stem
which connects the actuator (generally a hand wheel or motor) to the stem of the gate. If the valve has a rising stem its position can be seen just by looking at the position of the stem. A gate valve is used to control the fluid flow through lifting and descending the gate. A gate distinct feature is to provide an unobstructed passageway, which includes minimal pressure loss over the valve. When the gate is fully opened there is no restriction to the flow hence the pressure drop is low comparatively. Generally, the gate valve are fully closed or fully open as a partially opened valve may experience vibration which may lead to excessive wear. A gate valve's main component is the body, seat, gate, stem, bonnet, and actuator. the primary mechanism is straight forward where the handwheel is rotated to move the gate up and down via threads. they require more than a 360-degree turn to fully open the valve. Gate valves tend to be slightly cheaper than ball valves of the same size and quality. They are slower in actuation than quarter-turn valves and are for applications where valve operation is infrequent, such as isolating valves. Gate valves should be used either fully open or fully closed, not to regulate flow. Automated gate valves exist with either an electric or pneumatic actuator, but a manual gate valve is cost-effective since they have infrequent usage. Gate valves are widely used for all types of applications and are suitable for both above-ground and underground installation. They are suitable for most fluids including steam, water, oil, and gas, etc.
Geometry setup:
Extraction of fulid domain:
and we adjust the gate by moving up according to as per our requirement to run simulations
Meshing:
Setting up Ansys fluent:
Give the inputs like cell zones, boundary, conditions and etc
and run the simulations
setup parametric study by increasing gate valve 10 to 80
caseII
Flow coefficient and flow factor
The flow coefficient(Kv) 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.
where:
`Kv=sqrt((SG)/(dp)`
Q is the rate of flow in terms of gallon per minuit
SG is the specific gravity of the fluid
dP is the pressure drop across the valve in psi
The metric equivalent flow factor(Kv) is calculated using metric units
Kv=0.865*Cv
Cv = flow coefficient.
| valve displacement | mass flow rate | flow factor | flow coefficient |
| 10 | 0.36560927 | 107.6151 | 124.4105 |
| 20 | 0.36814791 | 108.3949 | 125.312 |
| 30 | 0.45225325 | 133.1263 | 153.9033 |
| 40 | 0.53747716 | 158.192 | 182.8809 |
| 60 | 0.75795288 | 223.0284 | 257.8363 |
| 70 | 0.85656576 | 252.1045 | 291.4503 |
| 80 | 0.93645357 | 275.6105 | 318.6249 |
blue is cv and red is kv.
conclusions:
Using the parametric study method saves a lot of time in the simulations which require performing the same operations for different settings multiple times.
In the parametric study of the gate valve, it was found that as the valve stopping is lifted gradually, the mass flow rate of the
fluid, and hence the flow factor and flow coefficient increase.