[behrouz]

hi
I'm try simulate semi close centrifugal compressor with cfx.
first i import my blade to bladegen then mesh in Turbogrid and setup in cfx-pre(Turbo mode) az below:
element number about 300,000 and
basic setting
1-steady state
component
2-22000 rpm
3-physical time scale 0.0002
4-tip clearance at shroud : yes
boundary condition
5-air ideal gas at 25C
6-relative pressure 1bar
7-inlet: p total , outlet: mass flow rate
8-p in=0 bar , t in=20 C
9- mass flow rate=0.2 kg/s per component
and for final step run it in cfx-solver and after several step solver stop and error message show up
"The ANSYS CFX solver exited with return code1.No results file have been created."
what happen and what i should to do??
before post this thread i read http://www.cfd-online.com/Wiki/Best_...omachinery_CFD
and
http://www.cfd-online.com/Wiki/Ansys...gence_criteria
and nothing help me.
thank you

[ghorrocks]

Your simulation is numerically unstable. This FAQ has some comments on what to do for unstable simulations: http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

[behrouz]

thank you for your reply
good advise
i try to solve the problem and if error show up again,hope help me again
tnx

[Red Ember]

Originally Posted by behrouz

thank you for your reply
good advise
i try to solve the problem and if error show up again,hope help me again
tnx

Hi! What's about your task? Have you changed boundary conditions?

[behrouz]

NO i did not change BC.
P total at inlet and mass flow rate at outlet,
but i used 'local time step' instead 'physical time step' and solution be more stable and in some case solution converge nicely.
but in the cfd-post the error show up and i have no idea what i should to do.
Error : color variable 'Mach number in stn frame' does not exit.
Error: No data exists for variable 'mach number' in stn frame ACA on spanwise plot of M abs at TE line specified in the series.
Error: The following unrecognised names were referenced:Hin ,Hout
Error: The following unrecognised names were referenced:Tin ,Tout

i post this errors in other thread and dear Glenn reply that but i still confused.

[ghorrocks]

Are you sure your rotating domains are set up correctly? Those errors suggest there is no rotating domain.

[behrouz]

Dear Glenn
i use turbo mode in cfx so i think rotating domain setup well,plus in cfd-post i use 'Temple centrifugal compressor rotor' to report solution and some diagrams like 'velocity vs %span' are fine but diagrams related to Mach number are empty.
when i set up tutorial number 25,run it,post processing it every thing is right and no error happen.
bad installation of 'ANSYS WORKBENCH' can affect this problem???
or
bad rotating speed set up(out of range between surge an choke) make this errors???
or
tnx

[ghorrocks]

Are you loading all domains into CFD-Post?

[behrouz]

I don't change any thing,just open cfd-post(result) and load 'centrifugal compressor rotor report' az below
file--->report..--->Load Templates---->centrifugal compressor rotor report
in beggining no error happen but when load template those error happen.

BUT

I use "Air Ideal Gas" instead "Air at 25c" in cfx-pre and run it and in cfd-post no error show up!!!!!every thing go right.
i can belive do such a simple mistake,i checked over and over and didn't attention the 'Air at 25 is not compressible'
Thank you Glenn.