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[ICEM] Meshing for Compressor Blades

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Old   October 8, 2013, 04:59
Default Meshing for Compressor Blades
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Hi experts,

I am currently keen to try out meshing on one-third of a compressor. However, I have problems with finding a suitable blocking for the blades.

Would Hexa meshing with O grids be advisable? I have attached the igs file of the compressor below, would any experts be kind to give me some ideas to get it started? (: Thank you!

https://www.dropbox.com/s/ae4z48ein0...o%20mesh.igs?m
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Old   October 9, 2013, 16:20
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I have not looked at your model, but yes, many commercial companies (and academics) use ICEM CFD hexa to mesh compressor blades.

Another popular choice, if your model is simple enough, would be turbogrid.

ICEM CFD Hexa has the advantage of flexibility (if you need fillets or squeelers or holes, etc.), TurboGrid has the advantage of ease of use if you model fits its templates... TurboGrid also has great smoothing designed for turbo models.

Tetra really isn't sufficient if you are trying to gain small improvements because the advantage is lost in the solver noise. In other words, when re-meshing with tetra, you can't really be certain if the slight difference in performance between two models is due to the geometry or the mesh.
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Old   October 10, 2013, 07:38
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Hi Simon, Thank you so much for your informative reply!! It shed light to why I am tasked to use ICEM hexa for meshing

Meshing was previously done in Gambit, but now I would like to see the meshing outcome from ICEM. As it is an assignment to be done in a tight schedule, would you be able to help me take a look at my geometry and assist me on the meshing ?

I'm still learning the basics of ICEM and any guidance would help me out a great deal Thank you!
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Old   October 10, 2013, 10:29
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Sorry, I can't. Already spent too much time on CFD-Online this week. I have a lot of other work to take care of and traveling all next week.

Look for the youtube videos and tutorials.

Here is the start of a 3 part one on a 2D airfoil that should give you a head start.

http://www.youtube.com/watch?v=tYrbScUH9RE
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Old   October 11, 2013, 00:14
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May be I can help you with the guidance from Simon. But in next week I will be traveling for Eid holidays (1500 + 1500 Kms ). So from next monday 21-10-2013 i will be available to work with you.

Note: File is downloaded, and I will interact you with whenever I get access to internet
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Old   October 11, 2013, 00:22
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Is this a mixed flow pump or centrifugal compressor with stator row?

Your leading edge surface is not following curves. curves show that it is rounded leading edge, but surfaces tell the different story (sharp leading edge ? ) .

Can you make these corrections before working on blocking?

One more question: Do you have tip clearance gap between blade tip and casing?

1. In my point of view, geometry has lot of issues and some of the issues can be tacked through advanced ICEM CFD projects commands, but I would strongly recommend to resolve these issues at CAD level.

2. It is may be due to IGES file format, so try to import in other formats such as sat or parasolid and see what you get there.

Edit : After build topology the original curves are gone and new curves are extracted from the sharp leading edge.








Last edited by Far; October 11, 2013 at 00:37. Reason: See Edit
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Old   October 11, 2013, 02:22
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Hello Far, thank you sooooooo much for helping me out !! I am very stressed up with the assignment as it is my first time approaching ICEM CFD and I didn't have much clue with such complex geometry .

This is a centrifugal compressor which have 9 pair of moving impellers and 12 stationary stator (diffuser) blades.

http://img405.imageshack.us/img405/7571/dhni.png
http://img24.imageshack.us/img24/4583/08ij.png

For this assignment, the geometry that was given to me consist of only one-third of the full compressor for simplicity. And I will apply periodicity effects at both ends of the blades to simulate fluid flows later on .

Another thing to take note is that this geometry consist of only 3 pairs of moving blades (1/3 of 9 blades). You can see 2 full pair of blades in the center. The last pair of blades are actually split into half and is made up by the blades at both ends to simulate continuity of the whole compressor. Would it be why you realised that the edges have weird angles ?

The only geometry file given to me was the iges file. What would be your advise ? Thank you so much for your time and guidance

Also thanks to Simon for the awesome video! I'm replaying it and following step by step as I learn the functions of ICEM


Updates: I managed to retrieve the IGES file representing the geometry of the full compressor. Do take a look and give me advises on whether meshing is better done here or the previous geometry (one-third) ?
https://www.dropbox.com/s/4uku43roq2...compressor.IGS

I have also found out that the tip clearance is 0.5 mm

Thankyou

Last edited by antornado; October 14, 2013 at 09:12. Reason: updates
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