|June 1, 2010, 07:03||
fan vs experimental data
Join Date: Apr 2010
Posts: 33Rep Power: 8
I am trying to generate a fan curve from experimental data using CFX. I have found that it does not converge steady state so I run it transient.
The fan is an axial fan but I am running in the stalled mixed flow region. I have found that my course mesh using wall functions (yplus100 on blade) is about 15% low in mass flow for a given loading. The steady state is way off.
I have yplus 30 and 1 cases running but they take forever. Perhaps a PHD using CFD was a bad idea.
Are these normal results for CFX? I have some friends who have done similar work with Star CD and they have got transient results within 5%.
I am not 100% that the experimental results are correct as the airflow was measured using anemometers and not a proper venturi setup.
Any advice anyone could give would be much appreciated.
|June 1, 2010, 18:46||
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,638Rep Power: 98
Getting accurate results in the stalled region is difficult, so you have a difficult project. That means you can expect long run times.
It also means you may not be able to use a turbulence model to get good results, you may be forced to use DES/SAS to get improvement - but that will just increase your run time more.
There are no simple answers in CFD, especially with difficult work like stall modelling.
I would be very surprised that the difference between your results and Star-CD is purely the solver. I would suggest either the user knew what he was doing better or was lucky.
|Thread||Thread Starter||Forum||Replies||Last Post|
|Tecplot. add experimental data into a mesh||Alejandro||FLUENT||0||December 10, 2008 08:08|
|How to update polyPatchbs localPoints||liu||OpenFOAM Running, Solving & CFD||6||December 30, 2005 18:27|
|Looking for the experimental data||COLOPOLO||Main CFD Forum||2||January 29, 2004 00:38|
|Simulated data vs. experimental data||moiami||FLUENT||0||December 19, 2002 02:03|
|Experimental data for fence at low Reynolds number||Kim Bindesboll Andersen||Main CFD Forum||1||September 26, 2002 13:54|