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multi-stage turbomachinery question

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Old   October 3, 2009, 16:24
Default multi-stage turbomachinery question
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Hello all,

I was wondering if anyone out there has any experience will multi-stage turbomachinery simulations. I have attached a photo.

As you can see, I'm trying to use a moving reference frame model to simulate motion in my rotor row. I'm planning on doing this by going to region->rotor->physics values - > moving reference frame -> and setting my value equal to omega *r, my desired speed. Is this an acceptable way to go about it?

The big question I have concerns the fact that my spacings for the blade rows are different, so my two pieces that I import into Star-CCM+ aren't of the same "height" as you can see in the photo. For the areas that do overlap, (drawn in blue), I am planning on using both "in place" and "indirect mixing plane interfaces". However, I am not at all sure about what I should do about the regions drawn in red. I was really hoping someone out there could throw me some pointers.

Also, if the approach I'm taking it completely wrong, please feel free to let me know. The biggest issue I'm having problems with is that my blade spacings are different, and thats def. making this more difficult than it otherwise would be.

Thanks for any help,
apc
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Old   October 9, 2009, 05:04
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Hi apc,

although I have no experience in modelling multi-stage turbomachinery with ccm+, I have been simulating compressors with Numeca and CFX. The beauty of the mixing-plane interface is that it was made exactly for this pupose/problem. If you provide the periodicity for the blade-rows you have a complete interface in between the two rows. This is what the circumferential averaging is for. So actually the red surfaces should be part of the blue surface as this should be one interface. They do not need to be a of the same perodicity. Though in heigth they should be the same. Sorry, I can not give you a more specific answer for this problem in CCM+. And I hope this is not too late anyway.

Quote:
I'm planning on doing this by going to region->rotor->physics values - > moving reference frame -> and setting my value equal to omega *r, my desired speed.
I'd say this is the only way of doing it.

By the way, I am working on a similar problem in ccm+ right now. Trying to get a mixing-plane interface in ccm+ working. So far it is not working, but I have tried only with a indirect interface. Now I will try to make it the way you suggested it with an additional in-place interface.

--mrjonezz
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