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Centrifugal fan impeller CFD simulation in OpenFoam

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Old   November 26, 2014, 05:53
Default Centrifugal fan impeller CFD simulation in OpenFoam
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Zach
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Hello,

I am totally new in OpenFoam at the moment.

Have heart that it is possible to make CFD simulation for rotating mechanisms such as impellers.

My case is shown at picture "1.jpg" - it is an impeller for centrifugal (radial) fan with backwards curved blades (blade is defined by: D1=510 mm, a1=40 deg, D2=1000 mm, a2=40 deg). I need to match the following:
1. Prise (Ptout - Ptin + rPref)
2. W (not really sure now which formula should I use)
3. Efftot (Q*pressure rise/shaft power*100)
4. Effstat (Q*(Paveout - Ptin + rPref)/shaft power*100)
where:
Prise - pressure rise in fan
Ptout - total pressure at outlet
Ptin - total pressure at inlet
Pref - reference pressure (in my case it is 1013.25 hPa)
W - shaft power (kW)
Efftot - total efficiency
Effstat - static efficiency
Q - flow
Paveout - average pressure at outlet

Basic parameters:
Gas density is 1.185 kg/m3 (air)
Temperature: 25 C
Rotation speed: 3000 rpm
Inflow: 1 m3/s

Where should I start from?
Is there kind of tutorial or example in this field?
Or someone maybe did similar simulation?
Do I have to set geometry in OpenFoam from zero or I can transfer existing CAD geometry (iges, step, ...) into OpenFoem directly?

I know that in Ansys simulation is prepared for one blade "2.jpg" and in stetup just amount of blades should be set to get results for entire impeller, is it the same in OpenFoam?
It also could be good to run kind of optimization to find optimal blade geometry.

Thanks in advance!
Attachment 35514

Attachment 35515
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Old   November 29, 2014, 04:22
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Hi Zach,
it is surely possible to simulate impellers in openfoam.
It is not the easiest topic for a beginner, but it can be done.
To import the CAD geometry, I would recommend using Salome as it gives you the opportunity to choose the right patches.
Then you can mesh with Salome itself or with snappyHexMesh or cfMesh.
Have a look here for the workflow:
https://openfoamwiki.net/index.php/S...l_Optimization
For turbomachinery, you should look at AMI or GGI for transient simulations, MRF for static.
check out also the turbomachinery Sig
http://openfoamwiki.net/index.php/Sig_Turbomachinery
If you need more help let me know!
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Old   December 3, 2014, 09:08
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Hello Christian,
thank you very much for help.
I started with Salome. Managed to import geometry:
but have problems with mesh:
What am I doing wrong?
Should be impeller geometry simplified somehow from the beginning?
May be instead of solids (front cone, back plate, hub) I should use surfaces?
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Old   December 3, 2014, 10:00
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Hi Zach, can't see the attachments, could you send me a private message with the pics? I'll try to get back to you as soon as I can!
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Old   May 16, 2024, 05:30
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Quote:
Originally Posted by crixman View Post
Hi Zach,
it is surely possible to simulate impellers in openfoam.
It is not the easiest topic for a beginner, but it can be done.
To import the CAD geometry, I would recommend using Salome as it gives you the opportunity to choose the right patches.
Then you can mesh with Salome itself or with snappyHexMesh or cfMesh.
Have a look here for the workflow:
https://openfoamwiki.net/index.php/S...l_Optimization
For turbomachinery, you should look at AMI or GGI for transient simulations, MRF for static.
check out also the turbomachinery Sig
http://openfoamwiki.net/index.php/Sig_Turbomachinery
If you need more help let me know!
@crixman

Apologies to Zach for hijacking his thread.

Hello, I write to ask for help installing Salome Meca on my Windows 10 Pro 64 bit machine so as to use it with OpenFOAM on wsl to investigate my centrifugal fan design having an aggressive inlet blade angle. I'm worried about an excessive angle of attack causing blade stall before spending $1.1K minimum on Carbon Fiber sheet for the rims and shrouds including the cost of having it cut on a water jet. I am unable to join/view the Salome Forum to ask for help due to detection by Malwarebytes Browser Guard of possible risks. I prefer not to risk it by adding exclusions or disabling Malwarebytes.

I am unable to install Salome Meca using Windows Power Shell as administrator and wsl. I have been duplicating the steps faithfully, as far as I know, from the YouTube video titled: "Installing official Salome Meca on Windows 10/11 using WSL2" on Hassan Berro's channel.

All the preliminary steps are accomplished successfully with the exception that I'm attempting to install on currently updated Windows 10 Pro 64 bit instead of Windows 11.

The difficulty arises at the point of attempting to import smeca_2022_wsl2_ubuntu_22.04.tar from drive D: into a folder on C:\ named SalomeMeca. The offending line is:

wsl --import smeca C:\SalomeMeca .\D:\SALOME\smeca_2022_wsl2_ubuntu_22.04.tar

The result is:
"The system cannot find the path specified."

I've tried everything I can think of, including placing the tar file on Desktop, as was done in the video, installing Microsoft Visual C++ 2017 Redistributable (x64) - 14, as was suggested for a similar post having the same Error message, to no avail. I moved the tar to drive D: to free up space on C: to have 10.5 GB free.

I have searched Microsoft.com and GitHub for help and found posts pertaining to the above error but none relative to Salome Meca.

Can you help?

Kind Regards,

David Walden, self-taught Python and Rhino 3D CAD enthusiast, retired pro pilot ATP ASMEL, CFII ASMEL (expired), Ground Instructor Advanced Instrument, IT nerd, classroom software instructor.
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Old   May 16, 2024, 11:20
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Please disregard my previous post. I've corrected the path and was able to get the import going. Now having issues with subsequent steps.
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Old   May 21, 2024, 10:05
Default Selecting Faces in Salome
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David Walden
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I have installed Salome and imported my fan into the geometry module.
From a YouTube video tutorial, the presenter explodes a globe (spelling?) valve in order to select faces. I have exploded my fan into 976 faces.
How does one select the wetted faces, i.e. the inside surfaces of the fan rim, the fan shroud, forward-facing and backward-facing blade surfaces?
Must they all be manually selected using the mouse?
My fan has 21 blades.

Last edited by DavidWa; May 21, 2024 at 10:22. Reason: context, readibiliy
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Old   May 21, 2024, 10:46
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Quote:
Originally Posted by DavidWa View Post
I have installed Salome and imported my fan into the geometry module.
From a YouTube video tutorial, the presenter explodes a globe (spelling?) valve in order to select faces. I have exploded my fan into 976 faces.
How does one select the wetted faces, i.e. the inside surfaces of the fan rim, the fan shroud, forward-facing and backward-facing blade surfaces?
Must they all be manually selected using the mouse?
My fan has 21 blades.

Yes, all should be selected manually using the mouse.
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Old   June 4, 2024, 11:02
Default Growing weary of waiting for hours on a mesh to compute only to fail
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David Walden
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Greetings. I have attempted to follow the Salome video tutorials offered e.g. "general ways of usage" and "meshing the bracket" in the creation of a mesh for my centrifugal fan created in Rhino 7 as a 3dm file in inches, converting inches to units in Meters, then saved as an STEP file and imported into the Salome Geometry Module.
After multiple attempts and failures at creating a mesh for use in OpenFOAM, thinking I would have better luck with a closed solid polysurface rather than separate solid closed polysurfaces of rim, an array of blades, and shroud, I have performed boolean union operations on the fan rim and blades, then on that resulting closed polysurface with the fan shroud, forming a one-piece closed solid polysurface.
The inner diameter is about 11 inch, or about 280 mm, outer diameter is about 12 inch, or about 305 mm. The fan blades are constant-chord tapered tip modified NACA 2412 airfoil having a leading edge length of about 1.4 inch, or about 36 mm, and a trailing edge length of about 1 inch, or about 25.4 mm
I've tried using NETGEN 1D-2D-3D, Hexahedron and Body Fitting Algorithms.

Upon clicking Compute Mesh, sometimes Salome Mesh pukes immediately, other times it computes for hours and hangs at 99% only to be cancelled and providing no useful results.
What am I doing wrong?

Last edited by DavidWa; June 4, 2024 at 15:03. Reason: clarity
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Old   June 15, 2024, 11:03
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Quote:
Originally Posted by ZachJa View Post
I started with Salome. Managed to import geometry:
but have problems with mesh:
What am I doing wrong?
Should be impeller geometry simplified somehow from the beginning?
May be instead of solids (front cone, back plate, hub) I should use surfaces?

Hello Zach,


Did you get a mesh computed successfully? I got some help with this issue from the Salome forum:
https://discourse.salome-platform.or...-9-12-0/1307/2
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