[zhangwc17]

hello,
I am trying to calculate a high-pressure-ratio centrifugal compressor by Numeca. However, when using "for turbomachinery" or "constant values" as the initial solution, it will always be diverged in a few steps. I have not solved it for three days. Is there any other way to facilitate the initial solution setup and calculation?


Thanks,
Alice

[Hamidzoka]

Hi;
Pleas note that:
1- when does your run case divegre? during coarse multi-grid iterations? or after the main solution with fine grids starts? each has a different meaning.

2- In fact "for turbomachinery" option has a limited success specially in case of compressors. You had better to select "constant values" option instead. For this purpose go to the list of "blocks and groups" on left side of initial solution page.Then use "Group" and "Ungroup" buttons to divide your domains to the blade rows you have; e.g. : R1,S1,R2,S2,etc.
Then give proper values for pressure, temperature and velocities (Specially Vr in your case) for each blade row. These values comes either from the guess (or sense) you have about your problem or zero-dimensional simple calculations (definitely without considering complicated loss models,etc.) which is mainly based on thermodynamics and can be done very quick.

Regards

[zhangwc17]

Hi Hamidzoka,

Thank you very much for that.
In fact, my run case is fine during coarse grids. It usually diverge after the second or seventh step with fine grids.
I'll try the "constant values" as much as I can.




Thank you.

Best regards,
Alice