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Old   January 5, 2008, 06:30
Default transonic rotor convergence problem
  #1
Noureddine
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Hi all,

I faced same convergence problem as posted before by Samad in this forum, with an indication that the maximum Mach number increase too much.

I have used CFX-TurboGrid 11.0 for mesh generation and the Turbomachinery template for the CFX-PRE 11.00

I want to know if somebody have successful to get a convergence with a transonic compressor (rotor37 i my case)? and if yes, plz, tell how you did it ?

any other advice is welcome

Regards Noureddine
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Old   January 6, 2008, 06:59
Default Re: transonic rotor convergence problem
  #2
Noureddine
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even I try to simulate the off-design flow (60% of design speed = 1080 rad/s) to have a subsonic axial compressor, I found same difficulty to converge. I used P-Total Inlet Mass Flow Outlet as boundary conditions, with, Reference Pressure = 1 atm, P-total = 0 atm, Mass Flow rate per Machine = 13.9 kg/s.

what is the problem ? any help is very welcome.

Regards Noureddine
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Old   January 6, 2008, 12:20
Default Re: transonic rotor convergence problem
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Noureddine
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It's OK, i found my mistake, it was the direction of rotation !!!!, we should indicate the sign of the rotation as -1800 rad/s for the design speed.
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Old   January 6, 2008, 18:23
Default Re: transonic rotor convergence problem
  #4
Amir
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Hi Noureddine,

Well i know you solved your problem but i have a small question. I am simulating a rotor in a stator (journal bearing) using turbomachinery template in CFX 11. I have a lubricant between my rotor and stator...When i do a transient simulation the residuals oscillating. did you have the same problem how did you solve it?
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Old   January 7, 2008, 02:42
Default Re: transonic rotor convergence problem
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Noureddine
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Hi Amir,

yes i had an oscillation of residuals in the last steps, but results was acceptable.

sorry, i have solved only the steady flow of a transonic compressor and i did not deal with the transient rotor/stator simulation.

Good luck Noureddine

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Old   January 8, 2008, 08:46
Default Re: transonic rotor convergence problem
  #6
pankaj
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Hi Noureddine!

the negative sign is for your rotors rpm,which is not always common,it specifies the direction of rotation.
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Old   January 8, 2008, 09:23
Default Re: transonic rotor convergence problem
  #7
Noureddine
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Hi Pankaj,

i know that's not always common, i am talking only about my own problem (own geometry) which is the axial compressor "rotor37".

you are right, it specifies the direction of rotation.

thanks for you message.

Regards. Noureddine
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