transonic rotor convergence problem
 

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

Re: transonic rotor convergence problem
 

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

Re: transonic rotor convergence problem
 

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.

Re: transonic rotor convergence problem
 

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?

Re: transonic rotor convergence problem
 

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

Re: transonic rotor convergence problem
 

Hi Noureddine!

the negative sign is for your rotors rpm,which is not always common,it specifies the direction of rotation.

Re: transonic rotor convergence problem
 

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