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-   -   [Other] Ansys meshing airfoil and / or compressor blades (http://www.cfd-online.com/Forums/ansys-meshing/79647-ansys-meshing-airfoil-compressor-blades.html)

baw192 August 30, 2010 08:34

Ansys meshing airfoil and / or compressor blades
 
3 Attachment(s)
Hi,

First of all let me say that I saw there are a lot of questions concerning airfoil meshing and I did read a lot of them for the last few weeks. If this question has been answered before and I missed it I am very sorry and would be happy if somebody can give me a link to the thread.

I am a student of aeronautics and currently work on a project on which I have to simulate the flow around 2D airfoils which I generate using javafoil, then import into DesignModeller and mesh the farfield with the mesher provided in the Ansys 12.1 workbench. I am working on this now for several weeks but do not seem to find a good solution. I looked at a lot of tutorials but they are either for Gambit which is no longer in use basically since the day I started or ICEM.

I created the farfield and the airfoil geometry in DesignModeler simular to the one used in this tutorial.
http://courses.cit.cornell.edu/fluent/airfoil/step1.htm

I used mapped meshing and tried to resolve the boundary layer as best as I could. However I is never satisfying. Any refinement of the mesh beyond the point where I am now results in an error. I used the y+ calculator to estimate the size of the first cell which come out to be 0.0000056m. But I cannot enter a length even close to that.
The y+ values stayed around 40 to 100. The only way I could bring them down was to use the refine mesh function in Fluent. Which resulted in a mesh with around 200.000 elements and a very high aspect ratio.

In the next step I want to use the same airfoil, but stack them on top of each other to simulate a grid of compressor blades. for that I want to use an O-grid around the airfoil which doesn't seem to be working very well either, I susbect it has something to do with the sharp trailing edge on the airfoil. But this problem is secondary.

Any help is appreciated. Thank you very much in advance.

Is Ansys mesher capable of this type of meshing or should I tell my Proffessor that it is way easier and worth it to get ICEM instead?

Thank you very much.
Regards
Markus

akash_morar January 1, 2011 11:38

how did you get a C grid?
 
Would just like to know how you got a C grid like that in the ansys default mesher, i've been trying for a while but havent succeeded. I've been creating and importing in curve files into the design modeller, making the the outer c grid shape and then meshing it with loads of different settings. What settings did you use?

PSYMN January 2, 2011 17:31

ICEM CFD to get the job done.
 
Yes, eventually ANSYS Meshing will be able to handle this, but not at the current release. I would suggest installing ICEM CFD to get the job done.

You can follow the ICEM CFD instructions at

http://www.youtube.com/user/ansysinc#p/u/8/tYrbScUH9RE

This is the first Video of three... If it doesn't immediately offer you the rest when it is over, you can find them here...

http://www.youtube.com/user/ansysinc

Best regards,

Simon

jsm January 2, 2011 21:38

Hi Markus,

One more suggestion. Convert your model to millimeter unit from meter. So you can avoid numbers with more digits after decimal point (like 0.0000056m --> 0.0056mm)

with regards,
JSM

jimbob April 1, 2011 05:10

problem with boundary settings in ICEM
 
Hi all,

I have followed the youtube tutorials for creating a mesh around a 2D airfoil with ICEM, rather successfully. However when I run my simulation in fluent, my y+ values are not correct (around 20-40). Like Markus I have used an online calculator to establish that the size of my first cell (starting from the airfoil) must be 8.3x10^-6 m (in order to get y+ roughly equal to 1). I have no idea how to do this with ICEM (being new to CFD), could you please help?
Thank you very much,

Best Regards

Jim

PSYMN April 2, 2011 09:58

Edge Params
 
Under Blocking tab => Premesh Params => Edge Params, you will find options to sent the end spacing of the radial Ogrid edges...

Just set the Spacing1 or Spacing2 (which ever is correct) to the 8.3x10^-6 m size that you wanted for your y+ = 1.

Don't forget to also turn on "copy parameters" "To All Parallel Edges"

gontxo August 24, 2011 07:15

Quote:

Originally Posted by jimbob (Post 301802)
Hi all,
Like Markus I have used an online calculator to establish that the size of my first cell (starting from the airfoil) must be 8.3x10^-6 m (in order to get y+ roughly equal to 1).

Hello,

Could you please post the link to that calculator?

thank you in advance!!

pete August 24, 2011 07:31

http://www.cfd-online.com/Links/tools.html#yplus

KKPradeep September 23, 2011 00:43

Hello Markus,
Can you please send me the replay file. I am getting error while doing the 3rd part of the video file.
please mail me at karrikumar@gmail.com

regards, Pradeep


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