Gate Valve Parametric Study

Aim :

To perform a parametric study for gate valve simulation at various opening configuration from 10% to 80%

Spaceclaim :

• The given geometry is imported in space claim

• The two flanges are extended on both directions using the boss extrude tool
• Volume is extracted using the volume extract option . Prepare >> Volume extract >> By edge

• Other parts of the gate valve are suppressed for physics, only the fluid volume is sent to meshing interface

Meshing :

• Before meshing, the inlet and outlet are named respectively using named selections
• The meshing is done with a total element size of 152852 elements
• The element sizing is given as 92 mm

• The mesh is then updated and transitioned into fluent.

Fluent:

Solver: Pressure based

Time: Steady state

Gravity : - 9.81 m/s2 on Z axis

Viscous model : K-epsilom Standard wall function

Inlet pressure : 10 Pascals

• For 10mm Valve lift

• For 20mm Valve lift

• For 30mm Valve lift

• For 50mm Valve lift

• For 60mm Valve lift

• For 80mm Valve lift

• For 90mm Valve lift

Flow Coeffecient

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 C_v (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 gravityof the fluid (for water = 1),

ΔP is the pressure drop across the valve (expressed in psi).

In more practical terms, the flow coefficient C_v is the volume (in US gallons) of water at 60 °F that will flow per minute through a valve with a pressure drop of 1 psi across the valve.

The use of the flow coefficient offers a standard method of comparing valve capacities and sizing valves for specific applications that is widely accepted by industry. The general definition of the flow coefficient can be expanded into equations modeling the flow of liquids, gases and steam using the discharge coeffecient

Flow Factor :

The metric equivalent flow factor (Kv; commonly used everywhere else in the world with the exception of the United States) is calculated using metric units

Kv = 0.865 Cv

Flow Coeffecient Vs Flow factor

Conclusion :

We can see from the data , that the mass flow rate increases with increase in the valve opening. This inturn increases the Flow coeffecient and flow factor .