Week 9 - Parametric study on Gate valve.

AIM - 

To perform the parametric study on the gate valve simulation by setting various opening levels.

OBJECTIVE - 

To perfrom the parametric study on the gate valve by setting the opening from 10% to 80%

To obtain the mass flow rate at teh outlet for each parametric study.

To calculate the flow cefficient and flow factor for each opening and plot the graph.

INTRODUCTION -

For a gate valve we know that the water will flow according to the level of opening for the valve. when the close the valve the flow stops compeletely and when the valve is opened the flow rate increases until the gate is competely opened. Here in this challenge the simulation is performed while keeping the various level of gate opening from 10% to 80% and analysis the result for the same if it shows the proper trend for the flow rate with the levvel of opening.

SOLVING AND MODELING APPROCH -

Here first the degsin is imported into the SpaceClaim module and then the required geometry is created using the extract volume command and also the gate is moved according to the reqirement and for this gate movement a parameter is setup.

next the geometry is loaded into meshing module and there appropiate mesh is generated and also inlet and outlet are named using named selections.

This mesh is ready for the fluent setup and proper physics is set up and also the solution conditions are set and then the simulation is run to obtain the results. here the flow rate will be set as an output parameter so it can be observed with changing input parameter.

form the parametric window we can add the input parameters form 10% to 80% and run the simulation of this parameters.

GEOMETRY - 

Load the design for the gate valve into SpaceClaim.

hide the bottom and the bonet component by unchecking the box for both the components from the structure. 

using the move command in the design tab select the gate and spindle component and move it by 10 mm as it is the 10% opening and set this movement length as the input parameter.

also pull the length of the inlet and outlet faces about 800mm 

now extract fluid volume using extract volume tool and suppress for physics all the solid components. 

the extracted volume looks like as shown below

lastly right click on the fluid volume and select the 'update volume body in context' button so that the volume genrage will be accroding to the movement of the gate and spindle.

Now our geometry is ready to load in mesher

MESHING -

First give the named selection at the inlet and outlet 

Now generate mesh with the default settings

The mesh has overall good quality as shown in the mesh metrices

also the number of elements is good and within the acadamic limits of the software

Now this mesh can be used to setup the fluent case for the simulation

FLUENT SETUP - 

here a pressure based solver is used and time is kept steady also the gravity is enabled in the negatice Z direction .

now here the viscous model used is Realizable K-epsilon turbulence model with scalable wall function. 

the material is added as the water liquid from the fluent database and it will be used so the cell zone material is set to water.

a flux report definition is create at the outlet to measure the mass flow rate and an output parameter is also selected so the mass flow rate can be observed with change in the input parameter.

Now the solution is initialized using standard initialization computing from the inlet and it is run for about 250 iterations to get stable results. 

RESULTS -  

The result for this simulation can be obtianed in the from of the mass flow rate as the outut parameter. so it is necessary to run the simulation for different values of the gate lift which is used as the input parameter. 

following image shows the various values used for the input parameter and the outut parameter that is obtaind by running them.

here the 0mm is for the 10% lift and then with each increament the gate lifts by 10% so here in this image the lift is shown from 10% to 80% and we can observe that as the gate is lifted the mass flow rate is also increased.

the value if mass flow rate is negative because the flow is out of the control volume.

For the 80% lift we get some bad mesh qulaity due to which the result for that case are diverging from the trend. though all the other results are quite satisfying .

Following table shows the conversion of the mass flow rate in US gallons per min and cubic meters per hour also it shows the calculation of the flow coefficient and flow factor for each input parameter of gate lift.

Conversion of mass flow rate from kg/s to cubic meter per hour 

1 kg/s = 3.60649 cubic meters per hour

Conversion of mass flow rate from cubic meters to US gallons per min

1 m^3/h = 4.40287 US gallon per min

Flow Coefficeint

`sf"Flow coefficeint" = Q * sqrt((SG)/(DeltaP)`

where Q = mass flow rate in US gallon per min

SG = specific gavity

`DeltaP` = pressure in PSI

Flow Factor

`sf"Flow Factor" = Q sqrt((SG)/(DeltaP)`

where Q = mass flow rate in cubic meters per hour[m^3/h]

SG = specific gravity 

`DeltaP` = pressure in bar

the plot for the mass flow rate with the openig in the gate valve is shown below. we can clearly see that the increament is almost linear.

The plot for the comparison of flow coefficinet and flow factor is shown below

we can see that the flow coefficeint is increasing linearly with increase in the percentage opening of the gate valve.

CONCLUSION -

1. The mass flow rate increase with increase in the opening of the gate valve.
2. The Flow Coefficeint also inceases with increase in the opening of the gate valve.
3. We can use the parameters in Fluent to preform various simulation and it is very easy to setup and less time consuming.
4. There are still chances that the simulation may not be accurate as we obsserved that in case of the 80% opening.