[VishalSunak]

Hello all,
I'm doing multistage axial compressor in CFX (version 2019R2). Using default "Stage" interface settings, which says "Mixing plane" and I don't activate the "Implicit Stage Averaging".

I always thought, that the way, Stage interface works is that it takes a circumferential band on a certain radius, averages the value and then passes it to the next passage with respect to rotating/stationary frame conversion.

So, the inlet profile for the consequent blade row should be circumferentially uniform?

Unfortunately, I don't see it in my compressor, and for right or wrong reason, my total pressure is larger at the suction side of the blade (see the attachment). And the variability is about 20% of the pressure rise.

I've checked the plots of P0 at the stator inlet - it seems like a potential flow field from the stator leading edges is propagating upstream (see the attachment).

The axial gaps between rotors and stators are quite short, and the LE potential field would expand much further away, I suppose.

Any ideas whether it is a right thing to happen (I mean, the circumferential non-uniformity at the second side of the Stage interface)? In my project I consider local values of the flow in proximity to the stator, so for me this uniformity (or not) is crucial.
Thank you

[Opaque]

For the default settings (constant total pressure in the relative frame if I recall correctly, it is a total pressure constrain, not a static pressure constrain.

perhaps worth a look at that variable in the post-processor.

On the implicit stage averaging, it is a setting to improve convergence for cases with mild recirculation regions, and it should not change a converged solution in any way or form.

[VishalSunak]

Originally Posted by Opaque

For the default settings (constant total pressure in the relative frame if I recall correctly, it is a total pressure constrain, not a static pressure constrain.

perhaps worth a look at that variable in the post-processor.

On the implicit stage averaging, it is a setting to improve convergence for cases with mild recirculation regions, and it should not change a converged solution in any way or form.

Hi, thanks for the reply.
The plot shows Total pressure indeed, not the static one. I would accept that the static one is variable.
I attach all the interfaces here - they all had default settings, and all the plots are total pressures, and they are all different...

[Opaque]

You have 3 different total pressures:

1 - Total Pressure in Stn Frame
2 - Total Pressure in Rel Frame
3 - Total Pressure

which of the 3 did you compare? Only one can be maintained constant, please read the documentation for the details

[VishalSunak]

Originally Posted by Opaque

You have 3 different total pressures:

1 - Total Pressure in Stn Frame
2 - Total Pressure in Rel Frame
3 - Total Pressure

which of the 3 did you compare? Only one can be maintained constant, please read the documentation for the details

The plots for stator are "just" Total Pressures. I've tried all three of them for stators inlet - they are all the same.
Stator 1 sees the LE pressure field (as on the very first picture), and stator 2 has uniformed flow. But all the interfaces were made default.