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Oiling in rotating pipe

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Old   March 8, 2016, 04:28
Default Oiling in rotating pipe
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Hans Meier
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Hello to all,

im very glad to be part of this forum and im looking forward to discuss about CFD!

I have a problem about the oiling in a rotating pipe.
In the picture there are 3 different pipes (different colours), which have different RPM and are connected by an internal interface. The first pipe is like an tunnel from which the oil flows in. The second pipe is rotating with 5000 RPM and has also 3 radial outlets. The last pipe do not rotate.

About the setup:
Turbulence model, k-Omega SST
multiphase model, VoF-Model (Air, Oil)
transient simulation with adaptve time stepping (CFL condition)
incombressible flow
Massflow inlet, 5 liter / min (~0,5 m/s at the first internal interface)
Pressure Outlets with backflow conditions
Gravity is on

At the beginning the pipes are full of air and the rotating pipe is rotating with its RPM (5000 RPM). Therefor the air in the second pipe has already a swirl flow. To start the simulation the oil flows from the inlet through the first pipe. In my opinion, the rotating pipe is like an radial pump cause of the centrifugal force. If the oil phase reached the rotating pipe, the swirl flow of the air has to effect of the incoming oil phase because of the shear stress. So the swirl flow impress the oil phase and subsequently the oil phase will also get an swirl. Because of the different density (and inertial forces) the oil will pressed outwards to the wall and the air will pushed to the inside. Do I have any thinking errors about the theoretically?

The simulation is like an flow through 3 standig pipes and the oil will not pressed outwards to the wall of the second pipe! I insert some sketches about the initail conditions, the CFD result an the theorie, i hope this will support my explanation!

Do you have any ideas what might be wrong?

Thank you very much!!!!
Attached Images
File Type: png initial.PNG (18.8 KB, 28 views)
File Type: png CFD.PNG (21.5 KB, 20 views)
File Type: png Theorie.PNG (22.3 KB, 16 views)

Last edited by Brozicek; March 8, 2016 at 06:11.
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Old   March 8, 2016, 06:12
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Hans Meier
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FYI:


Oil:
Dynamic Viscosity = 0.0645 mPa s
Density = 800 kg/ m^3
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Old   September 6, 2016, 10:45
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Hello Brozieck,
I am actually working on a similar case, have you managed to run the simulation?
I am interested in any eventual results.

Regards
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