[Julian121]

I am reading a paper on the necessity of doing transient simulation to study the effect of axial and vaned-recess casing treatments on a compressor.
The paper emphasizes that steady state simulations does simplify the problem.
"While some CTs, such as circumferential grooves, can be described by a rotation surface and can thus easily be included in conventional steady
simulations, the CFD analysis of other casing treatments like axial slot or recessed vanes, currently requires a time-resolving analysis of the interaction between such structures and rotating parts."
The reason is not clear for me although I have seen this in a few papers.
I have been doing steady state simulations to understand the physics of vane-recessed casing treatment.
The paper mentions that a mixing plane interface makes too large simplification and then concludes that a transient simulation is necessary.
I have used a frozen rotor interface in ANSYS CFX and not a mixing plane.
Does this apply to vane-recessed casing treatment in general?

[ghorrocks]

I have no idea what a vane recessed casing treatment is.

[Julian121]

Originally Posted by ghorrocks

I have no idea what a vane recessed casing treatment is.

Please see the attachment.

[ghorrocks]

There certainly is going to be an interaction between the blade and the cavity. This means mixing plane approaches do not sound appropriate, but frozen rotor should be OK.

Also with all those sharp edged cavities in there I would expect to see large separations, and that can be problematic for RANS approaches. I suspect accurate results will require a SAS or DES approach. But a RANS model should give you the general idea (as long as you don't mind a reasonable margin for error).