Week 9 - Parametric study on Gate valve.

AIM :- Parametric study on Gate valve.

INTRODUCTION

A gate valve controls the media's flow by lifting the gate (open) and lowering the gate (closed). A gate valve's distinct feature is the straight-through unobstructed passageway, which induces minimal pressure loss over the valve. The unobstructed bore of a gate valve also allows for a pig's passage in cleaning pipe procedures, unlike butterfly valves. Gate valves are available in many options, including various sizes, materials, temperature and pressure ratings, and gate and bonnet designs. A gate valve's main components are body, seat, gate, stem, bonnet, and actuator (Figure 2). The primary operation mechanism is straightforward. Turning the handwheel rotates the stem, which moves the gate up or down via the threads. They require more than one 360° turn to fully open/close the valve. Lifting the gate from the path of the flow, the valve opens. Lowering the gate to its closed position seals the bore resulting in a full closure of the valve.

For a gate valve, the relationship between the gate's vertical travel and the flow rate is nonlinear, with the highest changes occurring near shutoff. When used to regulate flow, the relatively high velocity of the flow at partial opening results in gate and seat wear, which along with possible vibrations of the gate, shortens the valve's service life.

GEOMETRY:-

FLUID VOLUME EXTRACTION

The fluid volume changes as the gate valve lift changes. For this, the verticle movement of the valve is parameterized.

After importing Geometry, hide the “Bottom” Part, so we can clearly see the “Gate Disc”.

• Then Select the “Gate Disc” component and move it in an upward direction by “10 mm” lift.
• To analyze the flow and its effects, we must allow the flow, and for that, we have given the 10 mm lift to the Gate Disc.

MESHING:-

Details:

1. Element Size: 10 mm
2. of Elements: 207472
3. of Nodes: 43496

SETUP:-

1. Here we have taken Pressure for inlet = 10 Pa.
2. In the Viscous model, we have taken the K-Epsilon model.
3. The reason behind choosing the K-Epsilon Viscous model is characteristic of the flow, which is turbulent.
4. For Reynolds No. about 2000 and more, flow is turbulent. So we have taken the K-Epsilon Viscous model.
5. But here, we have given Pressure Inlet, instead of Velocity Inlet. So knowing the velocity of the flow for correct Reynolds No. is required.
6. So, to know the velocity of the flow, we have to go for initializing the solution.
7. So, go to Solution, and select Standard Initialization, and Initialize from Inlet.
8. After initialization, we can get the correct velocity and calculate the Reynolds No. and from that, we can decide on the appropriate viscous model.

Geometry

1. Solver - Pressure Based
2. Time - Steady State

Model:-

1. Viscous - K -Epsilon (Realizable - Scaleable Wall Function)

Material:-

1. Fluid - Water

Boundary Condition:-

1. Inlet - Pressure Inlet ( Gauge Pressure - 10 Pa)

Method:-

1. Scheme - Coupled
2. Initialization - Standard from Inlet
3. Number of Iteration - 300

PARAMETRIC STUDY :-

Results:

Cases of lift of “Gate Disc” from 10% to 80% one by one.

• for all types of results, calculate the Flow coefficient and Flow Factor accordingly.
• Mass Flow Rate at Outlet, Flow Coefficient and Flow Factor and required Plots for each opening.

Cases:

Here we will discuss all cases according to the opening percentage of “Gate Disc”.

According to the opening of the valve, given as lift of “Gate Disc” in mm, all 8 cases are named as given below:

1. Case 1 = 10
2. Case 2 = 20
3. Case 3 = 30
4. Case 4 = 40
5. Case 5 = 50
6. Case 6 = 60
7. Case 7 = 70
8. Case 8 = 80

Case 1

Gate valve lifted by 10 mm

Case 2

Gate valve lifted by 20 mm

Residual and Mass Flow rate Plot

Case 3

Gate valve lifted by 30 mm

Residual and Mass Flow rate Plot

Case 4

Gate valve lifted by 40 mm

Residual and Mass Flow rate Plot

Case 5

Gate valve lifted by 50 mm

Residual and Mass Flow rate Plot

Case 6

Gate valve lifted by 60 mm

Residual and Mass Flow rate Plot

Case 7

Gate valve lifted by 70 mm

Residual and Mass Flow rate Plot

Case 8

Gate valve lifted by 80 mm

Residual and Mass Flow rate Plot

Conclusion:

1. Mass flow rate gradually increases as the lift of gate disc is increased.

2. The variation of flow coefficient and flow factor with the opening of the valve is studied by using parametric.

3. Parametric study is time reducing option when studying the effects of changes of certain parameters on a system.

4. Flow coefficient plays important role in the selection of valve and sizing of a valve, so calculating it is necessary.

5. flow coefficient also helps in computing the efficiency of the system and the effect of pressure on the system.