Challenge

Week 9 - Parametric study on Gate valve.

NNikhil Kumar28 Feb 2023

Week 9 - Parametric study on Gate valve.

CHALLENGE FOR GATE VALVE SIMULATION:

AIM:- For this challenge, you will have to perform a parametric study on the gate valve simulation by setting the opening from 10% to 80%.

Obtain the mass flow rates at the outlet for each design point.
Calculate the flow coefficient and flow factor for each opening and plot the graph.
Discuss the results of the mass flow rate and flow coefficient.

THEORY

Gate valve:

A gate valve, often referred to as a sluice valve, opens by raising a barrier (gate) out of the flow of fluid's passage. When the gate is completely opened, gate valves barely hinder the flow of fluid and take up very little space along the pipe axis. The gate sides are typically wedge-shaped but might be parallel (in order to be able to apply pressure on the sealing surface).

WORKING

A rectangular gate or wedge is placed into the flow of a fluid by a gate valve. They are controlled by a threaded stem that attaches to the stem of the gate and links the actuator—typically a hand wheel or motor—to it. If the valve has a rising stem, its location may be determined simply by observing the stem's position. The fluid flow is controlled by a gate valve that raises and lowers the gate. A gate's unique characteristic is to offer a clear path of travel, with little pressure loss over the valve.

As there is no flow restriction while the gate is fully open, the pressure loss is rather small.

The gate valve is typically entirely closed or fully open since a partly opened valve may vibrate and cause excessive wear. The primary parts of a gate valve are the body, seat, gate, stem, bonnet, and actuator. The main mechanism is simple: the handwheel is turned to raise and lower the gate using threads. To fully open the valve, they need to spin it more than 360 degrees.

Comparable in size and quality, gate valves are often slightly less expensive than ball valves. They are used in situations where valve activity is uncommon, such as isolating valves, and have a slower actuation than quarter-turn valves. Gate valves shouldn't be utilised to control flow; instead, they should be used completely open or fully closed.Manual gate valves are more economical since they are used less frequently than automated gate valves, which can have either an electric or pneumatic actuator. Gate valves are frequently used for many kinds of applications and can be installed above ground or below. They can handle the majority of fluids, including steam, water, oil, and gas, among others.

Working Principle:

A gate valve's body, seat, stem, bonnet, and actuator are its main parts. The primary working mechanism is pretty straightforward. Turning the hand wheel causes the fluid to rotate, which is then converted by threads into the vertical movement of a Gate Disc. As it takes more than one 3600 turn to fully open or close the valve, they are referred to as multi-turn valves. As the Gate is raised from the course of the flow, the valve opens and when it returns to its closed position, it seals the bore resulting in a full closing of the valve.

Gate valve applications include:

Instead of regulating flow, gate valves are used to stop the flow of liquids. The ordinary gate valve has extremely little flow resistance since the flow route is unobstructed when it is fully open. As the gate is moved, the open flow path's size typically fluctuates nonlinearly. As a result, the flow rate does not alter consistently when the stem moves. A partially open gate may shake from the fluid flow depending on the structure.

Analytical Study:

Parametric analysis is one of the finest techniques to get the most out of your simulation. A full model may be customised to replicate situations with very little more work, with the only constraints being your computing power and time. You may evaluate the effects of altering particular factors as you proceed with your design. Dimensional parameters may be among the parameters. You may define the parameter range, describe the design restrictions, and evaluate the effects of each parameter modification using parametric studies.

A parametric study requires the following:

Design Objective is set to Parametric Dimensions
Parameters nominated for use in the simulation
Parameter ranges identified
Design criteria specified
Various configurations generated

We can assess our simulation once the settings have been produced. After we are happy with the outcomes, we may adjust the parameters or design limitations further. We can promote a configuration back to the model as a CAD edit if you've decided that it meets our design requirements.

Flow Coefficient:

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 Cv (or flow-capacity rating of the valve) can be expressed as:

where,

Q is the rate of flow (expressed in US gallons per minute),

SG is the specific gravity of the fluid (for water = 1),

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

10pa=0.00145038psi

In more practical terms, the flow coefficient Cv 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 are widely accepted by the industry. The general definition of the flow coefficient can be expanded into equations modeling the flow of liquids, gases, and steam using the discharge coefficient.

Flow Factor:

The metric equivalent flow factor (Kv; commonly used in Europe and Asia) is calculated using metric units:

Kv can be calculated from Cv using the equation as given below:

The Kv factor of a valve indicates "The water flow in m3/h, at a pressure drop across the valve of 1 kgf /cm2 when the valve is completely open.

Geometry:

Import the gate valve file into space claim

The model that was examined in Ansys Fluent is shown above. It has all of the characteristics of a gate valve. The Handwheel, Spindle, Bonnet, Gate Disc, and Bottom Part make up the gate valve. The valve is completely closed at first. For each design point of the parametric research, we must raise the lift of the gate disc. The lift of the Gate Disc is parametrized using the parameter option. The "move" command in Ansys Spaceclaim is used to provide the lift, and then the fluid volume is extracted. To generate the pipe shape, we utilise the "pull" command.

Initial Lift

Hide the "Bottom " Part , so we can claerly see the "Gate Disc".

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

Here we can see the green color arrow in upward direction, which shows the movement of "Gate Disc" in positive Z-Direction.
Also we can see the symbol of "P".
This symbol "P" is used to parametize the lift of the "Gate Disc".
After selecting the symbol "P", it turns in Grey color, and message shows that a Group has been vreaated for lift.
Created group for lift parameter shown in above image.
On the Left Side, in Tree Structure,if we see the group options, we can see created group and the amount of parameter, which has been set 10 mm lift.
We can simply change the value of parametrs from there directly.

Lift adjustments:

Case-1: Lift adjustment=10mm in positive z direction.

Case-2: Lift adjustment=20mm in positive z direction.

Case-3: Lift adjustment=30mm in positive z direction.

Case-4: Lift adjustment=40mm in positive z direction.

Case-5: Lift adjustment=50mm in positive z direction.

Fluid Volume Extraction

update the volume body in context

supress all other components other than fluid volume

Mesh:

First name inlet and outlet

Computational Mesh

We use the default computational mesh. Element size = 10 mm.

Set up:

1. Solver: Steady

2. Type: Pressure Based

3. Gravitational Acceleration:

X: 0
Y: 0
Z: -9.81 m/s²

4. Turbulence Model: Realizable k- omega with SST model

5.Cell Zone Condition:

Fluid: Water

6. Material Specifications:

Material: water-liquid (H₂o)
Density: 998.2 Kg/m³
Viscosity: 0.001003 Kg/m-s

6. Boundaries:

Inlet: Pressure = 10 Pa(Gauge Pressure)
Outlet: Pressure= 0 Pa (Gauge Presssure)

7. Solution Methods: Coupled

8. Initialization:

Method: Standard Initialization from the Inlet
Number of Iteration: 600

So, for Reynolds No,

ρ=998.2Kg/m³

V = 0.14145488 m/s

D = 0.1 m

Re=(ρ⋅V⋅D)/μ

= [998.2*0.1415488*0.1]/0.001003

= 14087.14

Here, Reynolds No is 14087.14, which is more than 2000.
So the flow is turbulent.
So the viscous model will be K-omega.
After initialization, Report Definitions for the report of Mass Flow Rate at the Outlet is created.
Also Contours for Velocity Magnitudes is created.
Animations for the flow of water inside Gate Valve based on Contours is created.
But here, we have given Pressure Inlet, instead of Velocity Inlet. So knowing the velocity of the flow for correct Reynolds No. is required.
So, to know the velocity of the flow, we have to go for initializing the solution.
So, go to Solution, and select Standard Initialization, and Initialize from Inlet.
After initialization, we can get the correct velocity and calculate the Reynolds No. and from that, we can decide for the appropriate viscous model.

OUTPUT

A.) PARAMETRIC STUDY OF MASS FLOW RATE

CASE - 1 , LIFT = 10MM

RESIDUALS

MASS FLOW RATE PLOT

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 2 , LIFT = 20MM

RESIDUALS

MASS FLOW RATE PLOT

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 3 , LIFT = 30 MM

RESIDUALS

MASS FLOW RATE PLOT

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 4 , LIFT = 40MM

RESIDUALS

MASS FLOW RATE

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 5 , LIFT = 50MM

RESIDUALS

MASS FLOW RATE

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 6 , LIFT = 60MM

RESIDUALS

MASS FLOW RATE

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 7 , LIFT = 70MM

RESIDUALS

MASS FLOW RATE

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

CASE - 8 , LIFT = 80 MM

RESIDUALS

MASS FLOW RATE

VALUE OF MASS FLOW RATE

VELOCITY CONTOUR

PRESSURE CONTOUR

TABULATIONS

LIFT	FLOW RATE (Q)	FLOW RATE (Q)	FLOW COEFFICIENT (Cv)	FLOW FACTOR (KV)
(In MM)	(In Kg/s)	(In GPM)	(In GPM)	In (m^3/h)
10 MM	-0.14155	2.2435675	58.910	50.958
20 MM	-0.22678	3.594463	94.3824	81.6408
30 MM	-0.34	5.389	141.502	122.4
40 MM	-0.44073	6.9855705	183.4252	158.6628
50 MM	-0.52485	8.3188725	218.4346	188.946
60 MM	-0.59617	9.4492945	248.116	214.6212
70 MM	-0.67835	10.7518475	282.3190	244.206
80 MM	-0.73966	11.723611	307.8353	266.2776

GRAPH PLOT BETWEEN Cv & Kv

CONCLUSIONS

1. As the lift of the gate disc is increased, the mass flow rate gradually rises.

2. Parametric analysis is used to examine how the flow coefficient and flow factor change as the valve is opened.

3. Parametric analysis is a time-saving choice when examining how changing a few parameters may affect a system.

4. Calculating the flow coefficient is necessary because it affects the choice of valve and the sizing of a valve.

5. The flow coefficient is also useful in calculating the system's effectiveness and the impact of pressure.

Week 9 - Parametric study on Gate valve.

Ship work like this
in your own course.

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Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.