Gate Valve Parametric Study
Objective
To perform a parametric study on the gate valve simulation by setting the opening from 10 % to 80%.
Introduction
A gate valve is used control the flow rate in a pipeline. It is generally used to completely shut off fluid flow or, in the fully open position, provide full flow in a pipeline. Thus it is used either in the fully closed or fully open positions. It consists of a valve body, seat and disc, a spindle, gland, and a wheel for operating the valve.
Gate valves work by inserting a rectangular gate or wedge into the path of a flowing fluid which is controled by wheel.
Geometry
Geometry of gate valve with dimesion.
Meshing
Meshing is done with default mesh size.
Simulation Setup
The model is considered as viscous and simulated using Realizable K-epsilon model with scalable wall function. Gravity (g=9.81 m/s2) is acting in negative z-direction. The working fluid is liquid water with pressure inlet at 10 Pa gauge pressure while gauge pressure at oulet is zero. Steady state model is simulated untill it get converged.
Result and discussion
a) 10% lift
Residual Plot
Mass Flow rate at outlet
Velocity contour
b)20% lift
Residual Plot
Mass Flow rate at outlet
Velocity contour
c)40% lift
Residual Plot
Mass Flow rate at outlet
Velocity contour
d) 60% lift
Residual Plot
Mass Flow rate at outlet
Velocity contour
e) 80% lift
Residual Plot
Mass Flow rate at outlet
Velocity contour
Calculation
Mass flow rate(kg/s):- It is defined as mass of substance flowing per unit time.
Mass flow rate`(dotm)=rho*Q`
Where Q is volumetric flow rate (m3/s)
ρ is density of fluid flowing (kg/m3)
Flow factor `(K_v)`
`K_v` is the flow coefficient in metric units. It is defined as the flow rate in cubic meters per hour [m3/hr] of water at a temperature of 16º celsius with a pressure drop across the valve of 1 bar.
`K_v=Qsqrt{{SG}/{DeltaP}}`
where Q is volumetric flow rate (m3/hr)
SG is specific gravity of fluid
∆P is pressure drop (bar)
Flow coefficient
`C_v` is the flow coefficient in imperial units. It is defined as the flow rate in US Gallons per minute [gpm] of water at a temperature of 60º fahrenheit with a pressure drop across the valve of 1 psi.
`C_v=Qsqrt{{SG}/{DeltaP}}`
where Q is volumetric flow rate (gallons/min)
SG is specific gravity of fluid
∆P is pressure drop (psi)
Table
Plot
Conclusion
Mass flow rate increses as increase in the percentage valve lift but flow becomes more chaotic. More iterations is required for the convergence of model with high lift.
Mass flow rate increases as the percatnage increase in valve lift. So, discharge also increases. Pressure drop decreases with increase in valve lift. Hence, flow factor and flow coefficient increases with increase in valve lift. From graph, it can be observed that value of flow factor and flow coefficient sharply increases between 20% to 60% valve opening.