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Old   January 15, 2007, 11:48
Default Compressor meshing
  #1
Jack
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Hi! Everyone, Does anyone here mesh a centrifugal compressor with all hex mesh? I got G/Turbo but still spending days to mesh just compressor. Dont think that is what I am paying for. Please share your experience if you have any. Thanks
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Old   January 15, 2007, 13:49
Default Re: Compressor meshing
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sam
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yes i have experience meshing with hex elements. what type of help u need.

regards sam
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Old   January 15, 2007, 18:50
Default Re: Compressor meshing
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Jack
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Hi! Sam, Nice to meet you. I am currently trying to mesh some centrifugal compressor and I have problems with keepig the skewness down in my hex mesh. The H volume decomposition obviously does work that well. Since there are already one or two one-click meshing software for turbomachinery out there, I dont think thats how G/Turbo should be. I hope I can later run Gambit in batch mode to mesh many compressors with some scripts, dont think I can do that with current procedures. So please share with me howabout you treat your leading edge of the blades and spliters. How did you manage to come out with good mesh quickily? Please tell me a little about your procedures. Thanks

Best wishes Jack
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Old   January 16, 2007, 07:28
Default Re: Anyone? Please help me.
  #4
Jack
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Is that the procedure described in the tutorial: low speed centrifugal compressor the only approach to mesh my compressor? I wish I can have more automated meshing.
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Old   January 16, 2007, 10:37
Default Re: Compressor meshing
  #5
Venkatesh V
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HI, I used to mesh with ICEM -CFD
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Old   January 16, 2007, 10:57
Default Re: Compressor meshing
  #6
Jack
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Hello, So please tell me more about ICEM. Does it produce nice smooth hex grids? How much human interaction involved? Does ICED support batch mode scripting? Can the mesh be exported to fluent? If it really does a good job then I would consider getting a license for that. Please keep in touch.
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Old   January 16, 2007, 12:18
Default Re: Compressor meshing
  #7
Venkatesh V
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ICEM-CFD is one of the good Hexa meshing software. And it has good smoother.

But it need more human interaction. But if you are going to meshing similar geometries ( the topology remains same) then you can mesh pretty fast.

You can export the mesh to Fluent and all other comercial softwares.

I think it will be somewhat costlier. I would like to one more point here, mostly CFX will be used for rotatory machinary. Even though Fluent and CFX gives nearly same answer, I find it easy to make the solution converge with CFX at high rotation speeds.
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Old   January 16, 2007, 19:59
Default Re: Compressor meshing
  #8
Jack
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That's right, at high rpm the solution stops to converge after reaching a certain point with Fluent. At transonic speed it is a nightmare. I can see Fluent is trying to apply many funny algorithms to improve this but the limitations still there.
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Old   January 17, 2007, 01:33
Default Re: Anyone? Please help me.
  #9
sam
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Dear CFD online fellow.

from my experience point of view, there is no easy way or short cut............

Gambit, Gridgen and ICEM can give nearly the same mesh quality (though Gridgen and ICEM are better in some way) if you can manipolute the software as requrired.

Can u please show your goemtry on CFD online if it is not trade secert.

Regards sam
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Old   January 17, 2007, 04:30
Default Re: Anyone? Please help me.
  #10
Jack
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Dear Sam I don't know how to post pictures here. But there is nothing new on my centrifugal compressor. Just the normal turbocharger type used in road vehicles. I am currently only trying to master the meshing techniques so I can try something unconventional later. But if I can't mesh the most common type now I won't be able to mesh a much complex one later (and there are many of them). However, I think the major problem is the blade attack angle which is almost perpendicular to the inincoming flow. So subdividing the turbo volume to find the best point to keep the skewness down is a disasterous nightmare. Furthermore the spliters make the problem worst. I know there are much better meshing softwares out there such as TIGER and ANSYS Turbogrid. NASA wrote thier own code called TCgrid written in Fortran code, which is an automatic mesher for compressors but it is not commercial nor open sourced. Anyway, Thanks in advance for any advace you can give.

Regards Jack

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Old   January 17, 2007, 10:22
Default Re: Anyone? Please help me.
  #11
sam
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you can do it manually by decomposing the volume as you requre.
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