Week 9 - Parametric study on Gate valve.
Aim: Parametric study on Gate valve.
Introduction:
A gate valve is a type of valve in which by operating spindle the flow rate of water can be changed. By operating spindle, disc valve can be lifted or lowered so that flow rate can be maintained. In current work flow analysis is done for different openings or lifts of a gate valve by setting parameters in a Ansys spaceclaim.
Geometry
A gate valve which is used in simulation is shown below. It has hand wheel, spindle, bonnet, bottom and gate disc.
Parameter creation
A parameter is created as shown below in the ansys spaceclaim. Initially gate disc is lifted for 10 mm and parameter is created for motion of gate disc along z- axis (green in colour).
After this bottom is extended by a distance of 800 mm on either sides as shown below.
Fluid Volume extraction
After exteding bottom, fluid volume is extracted, as shown below.
Step 1: Selecting edges
Step 2: Inner highlighted part is fluid volume
Step 3: To hide bottom
Mesh
Element size : 5.5 mm
No. of elements: 492240
No of nodes: 98969
Named selections:
Simulation settings:
General settings
Turbulence models
Materials
Cell zone conditions
Boundary conditions
Inlet: Pressure inlet
Outlet: Pressure outlet
Wall: Wall BC
Interior: Interior BC
Solution methods
Controlls:
Initialisation
Results:
1) Gate disc lift 10 mm
2) Gate disc lift 20 mm
3) Gate disc lift 30 mm
4) Gate disc lift 40 mm
5) Gate disc lift 50 mm
6) Gate disc lift 60 mm
7) Gate disc lift 70 mm
8) Gate disc lift 80 mm
Calculation of flow factor and flow coeficient
Sample calculation for 10 mm lift
flow coeficient is given by
`Cv = Q ((SG)/(ΔP))^0.5`
and flow factor is given by,
`Kv = 0.865 Cv`
Where,
Q is volume flow rate in US gallons per minute, SG is specific gravity of fluid (for water = 1) and ΔP is pressure drop in psi.
for 10 mm lift, ΔP = Inlet pressure - Outlet pressure = 10 - 0.18578 = 9.81422 Pa = 0.001423432266 psi
`And Q = mass flow rate / density of water = 0.15069467/1000=1.5 e-4 cubic meter/sec = 9.041 e-3 cubic meter/min = 2.38837953 US gallons/min
Hence, Cv = 2.38837953 * (1/0.001423432266)^0.5 = 63.3 and Kv = 0.865 * 63.3 = 54.75
Similar procedure is follwed for all other lifts of gate disc and following results are obtained
Varaiation of mass flow rate at outlet with gate disc opening
Varaiation of flow coeficient with gate disc opening
Varaiation of flow factor with gate disc opening
Conclusion:
It is found that, with incresed in gate disc opening
- Pressure at outlet increses
- Mass flow rate at outlet increses
- Flow factor increases
- Flow coeficient increases