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relative velocity for a radial turbine wheel

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Old   December 15, 2011, 05:45
Default relative velocity for a radial turbine wheel
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Niklas Winkler
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Hi all,

I have a set of transient data for a radial turbine including the event file (.evn) and would like to compute the relative velocities in the wheel. The wheel rotation is simulated with the sliding mesh technique. Could anyone please give me a hint of how to or point me to a relevant tutorial.

Thanks
/NW
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Old   December 15, 2011, 08:20
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Joern Beilke
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Use the "reframe" command.
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Old   December 15, 2011, 08:24
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Niklas Winkler
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Thanks for your quick reply!

I've tried the following, reframe,2,local,(OMEGA), used the second coordinate system with the following command, csys,2 and then tried to extract the data again. However, it subtracts the data from the entire field and not just from the wheel. Do you know how I can specify a part of the field to get relative velocities at the wheel only?

All the Best
/NW
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Old   December 15, 2011, 09:48
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Joern Beilke
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There are 3 possibilities for using the command.
  • refr stat
  • refr compu
  • refr loca icsys omega
Just try what gives the best results.

I don't see an easy solution for the other problem right now.
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Old   December 15, 2011, 12:54
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Robert
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I would think that you should be able to get there from here with OPERATE and CHANGE

If you use PSYS to set the basic system for post processing

Then you can

Getc,all

to get the vectors in the axis of the rotor

Oper getc x axis_syst 5

Oper smult omega 5 5

Cset news all non rotating cells

change cset 0 0 0.0 0.0 5

oper subt 2 5 2

Oper unrotate


Not sure if this does exactly what you want but some combination of the above commands or similar should get you there from here
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Old   December 22, 2011, 11:33
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Niklas Winkler
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Thank you! The command oper,refr,local,(coord syst),(omega) did the trick!

All the Best
/NW
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