[CmdrFALCO]

Greetings,

My name is Cristian and I am new to the forum but not new to FloEFD V5.
I have worked in the past with FloEFD V5mainly in designing liquid to solid heat exchangers, where it predicted pretty well the actual measurements made on the prototypes.
Now I work for a different company for a month now, where amongst other responsibilities I help in choosing axial or radial blowers for thermal management solutions.
Because of my good experience with FloEFD V5 I want to propose to get one for our department, and here I would like to address you.
Has anyone have good experience with FloEFD in simulating radial blowers, P-Q Curves?
When I was at my old company I have tried it with regional rotating region but the same model gave me different results at first, but the biggest problem was that it didn’t come near to the actual measured results. FloEFD predicted between 110 – 160 liter/minute and actual measurements showed about 410 – 420 liter/minute.
It was a simplified model, composed of the impeller and housing with a simplified duct at the outlet.
I made a surface at the inlet and outlet where I put the measurement surface and not even the inlet airflow was equal to the outlet airflow.

Did I make some mistakes or is FloEFD not so good in airflow simulations?


Regards,
Cristian

[Boris_M]

Hi Cristian,

FloEFD should give correct results as some pump manufacturers use it and the same goes for fans.
Rotating objects such as a pump impeller or a fan need some more focus on the correct setup of the rotating region and some other boundary conditions. They might not converge directly but fluctuate for some hundred iterations but with the correct settings they give good results.
The difference between the inlet and outlet airflow problem you described sounds to me like a not yet converged simulation. It can even appear that you will get outflow in both openings for some iterations but as you let it calculate this will vanish and the correct values will settle in.

In general P-Q curves are the easiest way to represent a fan or pump. However not all fans can be treated as a simple P-Q curve as they might be too close to an obstacle which will influence the flow upstream, so into the fan, and that is not considered by a simple fan curve. For such cases you should use the rotation of the fan.

FloEFD comes now with the old approach which was in the software for years (rotating reference frame or mixing plane approach) but also since V14 it has the sliding mesh approach which is a fully transient calculation by nature as the mesh of the rotating region actually rotates. Depending on the fan type of application or post processing you want to do, either way might be interesting also from a CPU time point of view.

If you are interested in testing FloEFD for your application, you can always contact Mentor Graphics and ask for a benchmark. The engineers there can help you setting it up correctly and you can get a license to run some tests on your own. If you face any problems, feel free to contact them and ask for help.
Often a new application can require a different setup and boundary conditions, but the engineers at Mentor can help you with that.
And since you know how to use the software you don't need a training, maybe some tips or tricks on how to set it up correctly but if you are used to the software and feel comfortable in using it, you should be able to run your own simulations right away.

Regards,
Boris

PS: Depending on where you come from I might be able to give you some references. You can drop me a private message with more information on the application and where you are from. We have some customers such as Universities etc. that you could get some feedback from as of course competitors to your new company might not be willing to do that.

[CmdrFALCO]

Greetings,

Thanks for the info!

I will get back at you as soon as I can.
I am located in Germany, north of München.

Regards,
Cristian

[Boris_M]

Yes, feel free to contact me. I'm located in Frankfurt.

Grüße,
Boris