Parametric Study on Gate Valve

Objective :-

• To perform a parametric study on the gate valve simulation by setting 5 design points starting from the initial condition of lift with the least value of mass flow rate.
• Obtain the mass flow rates at the outlet for each design point.
• Show the cut section view for all the design points.
• Show the velocity contour animations for the design points

Introduction :-

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. The gate faces can be parallel but are most commonly wedge-shaped (in order to be able to apply pressure on the sealing surface).

Uses :-

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

Case Setup :-

Geometry :-

Fig : Gate valve for simulation

Fig : Sectional view of the gate valve

Geometry Extension

Extend the geometry by 800 mm using pull command from both side (inlet and outlet) for the flow of fluid is proper developed.

Volume extraction

For the CFD analysis we created fluid domain by the tool Volume Extract inside ANSYS Spaceclaim and rest of the solid body not considered for the physics calculation.

Parametric Study

For this challenge we have to perform a parametric study on the gate valve simulation by setting up 5 design points starting from the initial condition of lift with the least value of mass flow rate.

Five Design Points are :

1. 0 mm (initial position)
2. 10 mm lift
3. 20 mm lift
4. 30 mm lift
5. 40 mm lift

Meshing

• Element size = 6 mm

Table : Mesh detail for every design points

Boundary condition :

Inlet

• Pressure inlet = 10 Pa (Gauge pressure)

Outlet

• Pressure outlet = 0 Pa (Gauge pressure)

Simulation Setup :

Setting up the physics for Gate valve in ANSYS fluent.

• For this case we are using pressure-based transient solver
• Velocity formulation - Absolute
• Gravity Acceleration
  
  • X-direction = 0 m/s^2
  • Y- direction = 0 m/s^2
  • Z- direction = -9.81 m/s^2

Viscous model :

• model - k-epsilon
• k-epsilon model - Realizable
• Near wall treatment - scalable wall function

Material :

• Water

Boundary condition and simulation setup is same for all the five design points.

Simulation Result :

Design point I : Initial condition 0 mm lift

Fig : Cut section view for the design points

Fig : Residual

Fig : Mass flow rates at the outlet

Fig : Velocity contour

Animation : Velocity Contour

Design point II : Disc displacement = 10 mm (Lift)

Fig : Cut section view for the design points

Fig : Residual

Fig : Mass flow rates at the outlet

Fig : Velocity contour

Animation : Velocity Contour

Design point III : Disc displacement = 20 mm (Lift)

Fig : Cut section view for the design points

Fig : Residuals

Fig : Mass flow rates at the outlet

Fig : Velocity contour

Animation : Velocity Contour

Design point IV : Disc displacement = 30 mm (Lift)

Fig : Cut section view for the design points

Fig : Residuals

Fig : Mass flow rates at the outlet

Fig : Velocity contour

Animation : Velocity Contour

Design point V : Disc displacement = 40 mm (Lift)

Fig : Cut section view for the design points

Fig : Residuals

Fig : Mass flow rates at the outlet

Fig : Velocity contour

Animation : Velocity Contour

Parametric result for every design points :

In the above table mass flow rate shown at the outlet for every design points.

Note : Negative sign in mass flow rate indicates that the fluid is leaving or moving out to the pipe.

Conclusion :-

• So by the above study we observe that as the valve lift increases mass flow rate at the outlet increases. It means all the design points result update successfully.
• Parametric study is very useful and time saving where we have to find result at different design points.