Week 4.1: Project - Steady state simulation of flow over a throttle body

STEADY -STATE SIMULATION OF FLOW OVER A THROTTLE VALVE

Aim :-

To simulate the flow over a steady-state simulation of flwo over a throttle body.

Objective :-

• Perform a steady-state simulation of flow over a throttle body.
• Post-process the result and show pressure and velocity contours.
• Show the mesh with surface edges.
• Show the plots for pressure, velocity, mass flow rate and total cell count.

Introduction :-

Throttle Body:-

In fuel-injected engines, the throttle body is the part of the air intake system that controls the amount of air flowing into the engine,in response to driver accelerator pedal input in the main. The throttle body is usually located between the air filter box and the intake manifold, and it is usually attached to the mass airflow sensor.

Simulation Process

A. Geometry Setup:-

• Import the elbow.stl file in converge CFD.
• And scale the geometry from millimetere to meter.

Check Diagnosis by clicking on Diagnosis OR find at the right hand bottom.

Creating the boundary face and delete the thickness of the elbow.

Image - Delete outer Case

After deleting the thickness the open edge is created. Next, the open edge is closed by patch command. Select edge option & select by open edge and go to Repair --> Patch --> patch the inlet & outlet of the component.

Image - Delete the outer edge and make patches on it

• Go to Boundary --> flag --> make 3 new boundaries.

• Go to view option --> hide boundaries in order to Assign boundaries like inlet,outlet.
• Now, hide inlet & outlet boundaries and we will able to see the throttle body.
• Go to Daignosis --> click on clear.
• Click on Box pick [] and draw the mouse to see the component into a half in order to see the throttle.

Enable Normal and we can see some of the Normal point outward & some of the inward so but we can do we can simply press Normal Toggle once again and the outward issue is now resolved.

Click on Diagnosis --> Find --> now we can see all problem Traingles are resolved. Now, our boundary flagging is complete.

Next, go to the case setup

B. Case Setup:-

1. Application Type:- Time -based

2. Material:-

• Use Air as predefined mixtures.
• Enable gas simulation
• Enable reaction meachanism(mech.dat)

3. Simulation Parameters:-

• A study state solver is used.
• The steady state monitor is enabled.
• Use share memory is checked.

4. Simulation time parameters:-

• Average velocity, Total Pressure and Mass flow rate is monitored at outlet boundary conditions.
• Monitor start delay = 200 cycles
• Sample size = 100 cycles
• Initial time-step = 1e-9
• minimum time-step = 1e-9
• End time = 15000
• Maximum time-step = 1

Before moving to the next Assign boundaries

6. Solver Parameters:-

Boundary conditions:-

Now in case setup Go to boundary

Elbow = Wall with No-slip condition.

Throttle Valve = Wall with No-slip condition.

Inlet = Inflow with Pressure 150000Pa and Add air

Outlet = Outflow with Pressure 150000Pa and Add air

Here is see the images given below ;

Region & Initialization:-

1. Add Region i.e Region '0' and drag and drop the all four boundaries from the 'View option' & drop into the Region'0' and click OK.
2. Then go to boundary and click validate by right mouse button.

Grid Control :-

• Base grid
• Fixed Embedding

As we can see mesh before that is not refined near the throttle so let's apply embedded system

then i came back to geometry and activate Fixed Embedding

11. Output/ Post-processing:-

12. Export Data:-

Export all input file in the directory to run the simulation in Cygwin.

C. Execute the Simulation:-

To run the simulation in Cygwin using the command . The Executable 'mpiexec.exe -n 3 "converge.exe restricted are pasted in the input files.

D. Post-Processing the results in Paraview:-

1. Mesh:-

Meshing without Embedding

Meshing with Embedding

2. Velocity Contour

Velocity contour in the throttle valve

Velocity Contour of fluid flow

3. Pressure Contour:-

4. Throttle_Valve:-

5. Average Velocity line plot:-

6. Total Pressure line plot:-

7. Mass Flow Rate line plot:-

8. Total Cell Count:-

8. Animation:-

For Animation i am going to open PARAVIEW and upload the file from the destination folder by the extention .vtm and then click oK on Apply.

Next. click on slice and disable the 'show plane' and 'Triangular the slice' and hit the Z normal icon and click on Apply.

And choose the Appropriate parameters such a velocity, pressure according to requiremnets and edit the color to by clicking on'color map'

Pressure Animation:-

https://youtu.be/_1YKV_85-kM

Velocity Animation

https://youtu.be/-GLoLoxrzSU

Temperature Animation

https://youtu.be/wNHgSXrvQCE

E. Conclusion :

In a steady-state simulation, the flow of air is observed in the throttle body with variables of velocity and pressure.

For steady-state, the throttle valve is stationary when the airflow through the elbow.

The mass flow rate at the inlet and outlet is 0.04kg/s.Because the throttle valve is stationary and flow is steady-state so the airflow cannot be controlled.

The total cell count is through the entire cycle are no changes in cell count.

The pressure is high in the inlet of the elbow and the inlet throttle valve region.

The Velocity is high in the Outlet of the elbow and the outlet throttle valve region.

Bernoulli's formula explain the realtion of pressure and velocity is inversely proportional. It means that when pressure increases, the velocity decreases, kepping the algebraic sum of potenial energy, kinetic energy and pressure constant.