Radial Pump with Macros

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Lookid
Posts: 35
Joined: Wed Sep 12, 2018 7:39 pm
Location: France

Radial Pump with Macros

Postby Lookid » Fri May 01, 2020 8:43 am

I have been using freeCAD to prepare impellers and volute for CFD investigation, so what you see is the fluid zone.
The impeller is made step by step using 4 Parts, the volute is made in one Part. Everything with Macros and the parameters can be changed like a normal parametric part.
Everything is fast except at the last step for creating the fluid zone, I need to make Boolean operations to substract the solid blades from the fluid zone, and it can take ~2/3 minutes, because the base of the blade is defined by several layers of 200 points BSplines.

• First, set up the main dimensions of the meridional section
1_maindim.PNG
1_maindim.PNG (117.09 KiB) Viewed 1054 times

• Adjust the meridional section
2_meridional_section_adjustment.PNG
2_meridional_section_adjustment.PNG (190.32 KiB) Viewed 1054 times

• Set the blade angles
3_2DBlade.PNG
3_2DBlade.PNG (206.58 KiB) Viewed 1054 times

• Set Ellipse coefficient for blade leading edge, blade thickness, and some CFD parameters
4_3D_blades_solid.PNG
4_3D_blades_solid.PNG (179.45 KiB) Viewed 1054 times

• Here a full image ready for CFD, with the volute
6_with_volute.PNG
6_with_volute.PNG (133.23 KiB) Viewed 1054 times
kisolre
Posts: 2102
Joined: Wed Nov 21, 2018 1:13 pm

Re: Radial Pump with Macros

Postby kisolre » Fri May 01, 2020 10:25 am

Nice :)
Could you share a sample file and some simulation images?
Lookid
Posts: 35
Joined: Wed Sep 12, 2018 7:39 pm
Location: France

Re: Radial Pump with Macros

Postby Lookid » Fri May 01, 2020 10:38 am

I can share the file but it has no value since the MACROS are doing the job. But I can't share the MACROS, it's for work.

But I'm redoing the job in my free time with a better approach (for me), where I set up everything in Python and export points-ready to loft- to make the 2D blade. Making only the last step shown here relevant.
This I'll be able to share, but I struggle for some things so far :D

About simulations, I don't really have some now, but the goal is to automate python-FreeCAD-(SALOME for proper STL creation??)-OpenFOAM to quickly evaluate the design. I'll update here once I manage to do this if interested!
Attachments
sampleFile.FCStd
(990.71 KiB) Downloaded 17 times
johnwang
Posts: 266
Joined: Sun Jan 27, 2019 12:41 am

Re: Radial Pump with Macros

Postby johnwang » Tue May 19, 2020 12:28 am

Lookid wrote:
Fri May 01, 2020 10:38 am

About simulations, I don't really have some now, but the goal is to automate python-FreeCAD-(SALOME for proper STL creation??)-OpenFOAM to quickly evaluate the design. I'll update here once I manage to do this if interested!
If use openfoam, why not try to use the cfdof workbench inside FreeCAD?
Lookid
Posts: 35
Joined: Wed Sep 12, 2018 7:39 pm
Location: France

Re: Radial Pump with Macros

Postby Lookid » Tue May 19, 2020 11:36 am

johnwang wrote:
Tue May 19, 2020 12:28 am
Lookid wrote:
Fri May 01, 2020 10:38 am

About simulations, I don't really have some now, but the goal is to automate python-FreeCAD-(SALOME for proper STL creation??)-OpenFOAM to quickly evaluate the design. I'll update here once I manage to do this if interested!
If use openfoam, why not try to use the cfdof workbench inside FreeCAD?
The cfdof workbench doesn't support a lot of things, like rotating regions, cyclic patches, you can't place probes or so as you want, it is just more convenient for me to use OF normally in this case.
This workbench is great for quick testing really, great job. But I doubt it would be used as an accurate CFD tool.
kisolre
Posts: 2102
Joined: Wed Nov 21, 2018 1:13 pm

Re: Radial Pump with Macros

Postby kisolre » Tue May 19, 2020 12:02 pm

Lookid wrote:
Tue May 19, 2020 11:36 am
But I doubt it would be used as an accurate CFD tool.
If no real usage is tried no real tools can be added, tweaked, developed, ... People like you should push the boundaries :)
johnwang
Posts: 266
Joined: Sun Jan 27, 2019 12:41 am

Re: Radial Pump with Macros

Postby johnwang » Wed May 20, 2020 3:38 am

Lookid wrote:
Tue May 19, 2020 11:36 am
like rotating regions, cyclic patches, you can't place probes or so as you want, it is just more convenient for me to use OF normally in this case.
I was thinking you may need to simulate a part of the wheel (one passage) and the whole volute separately and how to connect them. It will be great to see one of this kind example.

Hope people are interested to expand the capability of the WB.
johnwang
Posts: 266
Joined: Sun Jan 27, 2019 12:41 am

Re: Radial Pump with Macros

Postby johnwang » Wed May 20, 2020 3:39 am

kisolre wrote:
Tue May 19, 2020 12:02 pm
If no real usage is tried no real tools can be added, tweaked, developed, ... People like you should push the boundaries :)
the free spirit
Lookid
Posts: 35
Joined: Wed Sep 12, 2018 7:39 pm
Location: France

Re: Radial Pump with Macros

Postby Lookid » Wed May 20, 2020 6:43 am

johnwang wrote:
Wed May 20, 2020 3:38 am
Lookid wrote:
Tue May 19, 2020 11:36 am
like rotating regions, cyclic patches, you can't place probes or so as you want, it is just more convenient for me to use OF normally in this case.
I was thinking you may need to simulate a part of the wheel (one passage) and the whole volute separately and how to connect them. It will be great to see one of this kind example.

Hope people are interested to expand the capability of the WB.
It is not a FreeCAD problem at this point but np :D.
If you make steady-state simulations of a radial pump like this, you have the problem that the solution will depend on the impeller position. It is due to the volute tongue or nose, depending on the languages. It's just where there's the connection to the outlet pipe. This is called the ''Frozen-Rotor'' Approach.
There is a way to do exactly as you said, simulate 1 passage, average circumferentially and transpose the results to the volute, it is called the ''Mixing-Plane'' approach. A version of this is implement in foam-extend, but I never managed to have it work properly.

Otherwise, as you said, you could compute 1 passage, compute the average velocities in the (r, theta, z) reference frame, and use those as inlet boundary conditions for the volute. I am not sure how accurate this would be, and at this point it might be easier to simply compute the whole pump in an unsteady simulation.

With the Workbench, it would be nice to have more functionality yes, or a full GUI for OpenFOAM. But that would be a LOT of work I suppose and the problem is that it is easy to simply deal with OpenFOAM besides the workbench, especially now that you can have OpenFOAM on Windows easily.

What do you think?
johnwang
Posts: 266
Joined: Sun Jan 27, 2019 12:41 am

Re: Radial Pump with Macros

Postby johnwang » Wed May 20, 2020 8:23 am

Unsteady simulation is straight foward, just need more cells.

I haven't tried cfdof, but found the elmer one a bit hard to use. Yes, it is easy now in windows for OF, maybe I should give it a go.