CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM

Individual Torque for Multiple Impellers Levels MRF

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes
  • 1 Post By tomf

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 16, 2018, 12:36
Default Individual Torque for Multiple Impellers Levels MRF
  #1
Member
 
Join Date: Apr 2011
Posts: 56
Rep Power: 15
Ruonin is on a distinguished road
Hi folks,

I've run a MRF single fluid simulation where I've used the libforces.so library in the controlDict dictionary to get the Torque in two different impellers level on the same shaft. I'm using MRF with simpleFoam.

This would allow me to get the individual Power Number for each impeller.

After convergence, and looking at the forces.dat files the data is essentially the same.

My question to the forum is: is there a way to get individual torques for each level of impeller? or do I need to run the different simulations with each impeller independently?
Maybe I'm looking at the torque calculation the wrong way...

Hope I was clear in my explanation.

Best Regards,
RS
Ruonin is offline   Reply With Quote

Old   March 20, 2018, 04:36
Default
  #2
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 634
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi,

This line is a bit vague:

Quote:
After convergence, and looking at the forces.dat files the data is essentially the same.
Can you plot the data?

Also in order to help you I think it would be best if you show you controlDict, or at least the entry for the forces.

Regards,
Tom
tomf is offline   Reply With Quote

Old   March 20, 2018, 09:36
Default
  #3
Member
 
Join Date: Apr 2011
Posts: 56
Rep Power: 15
Ruonin is on a distinguished road
Tomf,

I've uploaded the files.

My guess is that I need to separate the two levels of impellers into two different patches.

I'm guessing the shaft also has to be an independent patch.


FoamFile
{
version 2.0;
format ascii;
class dictionary;
location system;
object controlDict;
}

startFrom startTime;
startTime 0;
stopAt endTime;
endTime 100000.0;
deltaT 1.0;
writeControl timeStep;
writeInterval 100.0;
purgeWrite 0;
writeFormat ascii;
writePrecision 10;
writeCompression uncompressed;
timeFormat general;
timePrecision 6;
graphFormat raw;
runTimeModifiable yes;
functions
{

forces1
{
type forces;
functionObjectLibs ( "libforces.so");
patches ( impeller_Final );
rho rhoInf;
rhoInf 1000;
CofR ( -0.3418 -0.541 2.08 );
outputControl timeStep;
outputInterval 1;
}

forces2
{
type forces;
functionObjectLibs ( "libforces.so");
patches ( impeller_Final );
rho rhoInf;
rhoInf 1000;
CofR ( -0.3418 -0.541 2.9874 );
outputControl timeStep;
outputInterval 1;
}

}

forces1 ;
forces2 ;


Quote:
Originally Posted by tomf View Post
Hi,

This line is a bit vague:



Can you plot the data?

Also in order to help you I think it would be best if you show you controlDict, or at least the entry for the forces.

Regards,
Tom
Attached Images
File Type: png Forces_vs_Iteration_Bottom_Impeller.png (27.4 KB, 22 views)
File Type: png Forces_vs_Iteration_Top_Impeller.png (27.4 KB, 13 views)
Ruonin is offline   Reply With Quote

Old   March 21, 2018, 03:28
Default
  #4
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 634
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi,

Yes, if you want them to be separated, you need different patches for each part. You now just have twice the forces on impeller_Final. So if you split this into separate parts and make an entry for each part than you will get individual forces.

Good luck,
Tom
Ruonin likes this.
tomf is offline   Reply With Quote

Old   March 22, 2018, 13:13
Default
  #5
Member
 
Join Date: Apr 2011
Posts: 56
Rep Power: 15
Ruonin is on a distinguished road
Thanks, tomf.

I had already a ongoing simulation which confirmed your statement.

BR.

RS

Quote:
Originally Posted by tomf View Post
Hi,

Yes, if you want them to be separated, you need different patches for each part. You now just have twice the forces on impeller_Final. So if you split this into separate parts and make an entry for each part than you will get individual forces.

Good luck,
Tom
Ruonin is offline   Reply With Quote

Reply

Tags
mrf simplefoam, power number, torque

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[snappyHexMesh] Error snappyhexmesh - Multiple outside loops avinashjagdale OpenFOAM Meshing & Mesh Conversion 53 March 8, 2019 09:42
Issue with Negative Torque in 2D VAWT MRF Simulation fall3n FLUENT 0 December 22, 2017 18:50
pimpleDyMFoam with sixDoFRigidBodyMotionCoeffs: External Torque chaz OpenFOAM Running, Solving & CFD 0 May 7, 2017 19:22
Why air’s torque is negative and water’s torque is positive? Jackzm CFX 3 December 16, 2015 16:27
Torque Converter Pump Torque = Engine Torque? Torque_Converter Main CFD Forum 4 November 12, 2012 06:44


All times are GMT -4. The time now is 09:09.