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Thcfd December 22, 2010 04:50

Interface w. Pitch Change:
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Hello everyone,

Im having a small problem with the way CFX stretches or compresses the flowfield when an interface with pitch change is used. Here is my Problem:

Im currently working on the simulation of a turbine testrig. The rig consists of 4 bladerows of which the 3d one is the rotor. Now, due to the number of blades in each row (and of course time and memory requirements) im forced to use interfaces with a pitch change.
When im trying to do a simulation with a Frozen Rotor Interface (regardless whether steady state or transient), CFX stretches the flowfield between the interfaces as discribed in the manual. Ive added two small pictures of a geometry that i used to test different interface configurations, where you can see the stretching cfx performs.

This of course gives a rather wrong flowfield after an interface with a high pitch change (stretching of the wakes etc). In my case the pitch change after the rotor is from 15 to 24, where the domain with the 24 is the one im most interested in. What i have seen from a few things that i have tried is, that CFX is able to "add" information to an interface by periodically adding data to the interface (i tried periodic domains with a different "lean" at the interface).

My question is now whether there is a possibillity to prohibit the stretching on the interface, but to force the solver to do the add the information on side 2 of the interface by periodically copying the information from side 1

I hope that somebody is able to give me any advice or ideas how to solve the issue.

thank you

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