Screw Centrifugal Pump--FreeCAD to CFD

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ppemawm
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Location: Manhattan New York

Screw Centrifugal Pump--FreeCAD to CFD

Postby ppemawm » Sat Jul 04, 2015 8:15 pm

CFD (computational fluid dynamics) is used to better understand flow characteristics in pumps and compressors. The solid modeling task is to develop or extract the passages within the housings which contain the flow. These passages which must be a 'water tight volume' are meshed by the CFD software for use in the simulation constrained by the boundary conditions at the inlet and outlet. If part of the equipment is rotating such as in a pump that flow volume is designated a Moving Reference Frame. The CFD simulation then represents an instantaneous picture or 'freeze frame' of the flow conditions at one particular angular orientation during rotation.

The following screw centrifugal pump is a project for a client in which FreeCAD played a critical role. STEP models of the pump components were supplied by the client from their in-house high end CAD system.
Picture1.jpg
screw centrifugal pump assembly
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FreeCAD was used to extract the flow passages as shown in the following figure. Generally this involves subtracting a component from the boundaries of the flow passages. The impeller was a straight forward boolean cut, but the volute housing was a bit of a challenge. The figure shows the sequence required to obtain a clean flow passage. Several steps were required. The first was to make cuts on the housing essentially half way through the wall thickness. That left the internal passage and bits and pieces of the housing. The pieces go away when a pad or pocket is made on the part you want to keep.
Picture8.jpg
extracting CFD flow domains
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The solid components are exported as STEP files and imported into the CAD system for meshing as shown in the following figure.
Picture9.jpg
CFD flow domain and mesh
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Sample results from the simulation can include pressures, flow velocity magnitude and direction, hydraulic forces, and fluid drag or torque.
Picture10.jpg
sample output: static pressures and velocity vecotrs
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OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4671 (Git)
Branch: releases/FreeCAD-0-15
Hash: 244b3aef360841646cbfe80a1b225c8b39c8380c
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

CFD software: Symscape Caedium 5.2.0 (opensource OpenFoam)
"It is a poor workman who blames his tools..." ;)
danielfalck
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Location: Beaverton,Oregon, USA
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Re: Screw Centrifugal Pump--FreeCAD to CFD

Postby danielfalck » Sat Jul 04, 2015 11:02 pm

Wow, that is very impressive! If this were google plus and there was a +10 button, I would be pressing it :)
It's great seeing FreeCAD used in another commercial project. Thanks for sharing that.
Jee-Bee
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Location: Netherlands

Re: Screw Centrifugal Pump--FreeCAD to CFD

Postby Jee-Bee » Mon Jul 06, 2015 10:43 am

Wow Nice!!
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PrzemoF
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Re: Screw Centrifugal Pump--FreeCAD to CFD

Postby PrzemoF » Mon Jul 06, 2015 10:59 am

It looks impressive! Now I know where to look for testers when we extend the FEM module to do some flow calculations with CalculiX :D
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makkemal
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Re: Screw Centrifugal Pump--FreeCAD to CFD

Postby makkemal » Tue Sep 10, 2019 4:52 am

Do any of you think a process like this can be automated through scripting ?