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-   -   [ANSYS Meshing] Blade tip blocking (http://www.cfd-online.com/Forums/ansys-meshing/112464-blade-tip-blocking.html)

Bollonga January 29, 2013 10:28

Blade tip blocking (icem)
 
2 Attachment(s)
Hi everybody,

I'm meshing a three blade wind turbine and some blocking located at the blade tip are causing me trouble.
In the 1st picture you can see the blade tip with sharp trailing edge and its blocking. There are O-grid blocks around the blade and then all edges converge to a unique vertex in the very extreme of the tip + O-grid distance (vertex 624).
In the message box you can see that a collapsed edge is causing an internal error. This is causing negatives volumes as it is shown in the histogram (negative volumes for the same point of view are shown in the 2nd picture).

How can I avoid that?

Is there a better option for blocking at the blade tip?

Thanks in advance!

Far January 29, 2013 11:06

attach files.

energy382 January 29, 2013 14:31

that's not what I would call a sharp trailing edge...

Bollonga January 29, 2013 14:54

1 Attachment(s)
In the picture the visible edge is the leading edge. The trailing one is on the backward side.
Also, it can be confusing because there's a curve of the same colour as the surface.
But I think that's a sharp edge.

Thanks.

Bollonga January 30, 2013 06:06

Well, geometry files are not mine so I can't share them until I got permission. :D

I've realized that negative volumes are not only at the blade tip but in the whole blade surface. I'm gonna try a simpler blocking around the blade and I'll try again.

I'll keep posting.

Far January 30, 2013 06:14

Like this? :cool:


http://imageshack.us/a/img822/7977/sharpwing005.jpg

http://imageshack.us/a/img856/7364/sharpwing006.jpg

http://imageshack.us/a/img51/5707/sharpwing001.jpg

http://imageshack.us/a/img819/5300/sharpwing004.jpg


http://imageshack.us/a/img203/8971/sharpwing002.jpg

http://imageshack.us/a/img546/2905/sharpwing003.jpg

PS: This was not done by me. I guess this master piece was done by Ralen (But I am not sure)

Far January 30, 2013 06:45

see this post

http://www.cfd-online.com/Forums/ans...ca0009-3d.html

For 2nd thought

http://www.cfd-online.com/Forums/ans...spinnaker.html

Bollonga February 11, 2013 18:33

1 Attachment(s)
Hi, I'm back with the blade tip blocking after some days off. I've seen Ralen's approach but I have some questions. In the comment #12 of the thread:

http://www.cfd-online.com/Forums/ans...tml#post362126

In step 2 and 3 I don't know exactly in which surface I have to do the o-grid. I guess it's in the selected surfaces in the attached picture, if I am right how do I create an outer o-grid in just that selected surfaces? If I enable around selected blocks the o-grid appears all around the blocks, and not just in the selected surfaces.

Bollonga February 12, 2013 05:58

Quote:

Originally Posted by Bollonga (Post 407256)
In step 2 and 3 I don't know exactly in which surface I have to do the o-grid. I guess it's in the selected surfaces in the attached picture, if I am right how do I create an outer o-grid in just that selected surfaces? If I enable around selected blocks the o-grid appears all around the blocks, and not just in the selected surfaces.

I've already solved that, I was just messed up with the o-grid selection. :D

Bollonga February 13, 2013 11:18

5 Attachment(s)
After several trials I've managed to get some valid blocking for the blade tip following Ralen's approach. See picture 1 before associating vertices :cool:
Then I've made all the vertex-point, edge-curve and face-surface associations (picture 2 and 3).
But when I start meshing, there's somethins strange at the tip (see pictures 4 and 5), this has happened to me other times but I don't know how to fix it now. I've checked all associations and they seem all right to me. Why does this happen?:confused:

Bollonga February 13, 2013 11:36

Quote:

Originally Posted by Bollonga (Post 407634)
But when I start meshing, there's somethins strange at the tip (see pictures 4 and 5), this has happened to me other times but I don't know how to fix it now. I've checked all associations and they seem all right to me. Why does this happen?:confused:

Solved, I just had to move one of the vertex because it was to close to side1 instead of side2.

Far February 13, 2013 12:14

Quote:

Originally Posted by Bollonga (Post 407638)
Solved, I just had to move one of the vertex because it was to close to side1 instead of side2.

good...................

Bollonga February 20, 2013 05:45

5 Attachment(s)
I've found a new issue. I've been trying to solve it for a while but I can't find a solution.
The problem is that I want to mesh two parallel edges from a rectangular surface, everything pretty simple (purple surface in picture 1). I've done the associations point-vertex, edge-curve and face-surface. I do the bunching (picture 2), copying to all parallel edges, but it's not meshing properly (picture 3). The two long parallel edges are being mesh just from a concentrated point near the corners (pictures 4 y 5).

What is the cause? What can be the solution?

Thanks a lot!

PS: I don't know if I should open a new thread for this matter, as it is no longer related to the balade tip.

Far February 20, 2013 05:47

It is the association issue. check associations !

Bollonga February 20, 2013 06:10

2 Attachment(s)
Quote:

Originally Posted by Far (Post 408944)
It is the association issue. check associations !

I've checked all associations, even edge to surface ones (picture 1). Everything seem okay. I've done the same for the nearby rectangle and this one has been properly meshed (picture 2).

You think it's a edge to curve association issue of the two long sides?

Far February 20, 2013 06:12

Yes. It could be edge to curve or vertex to point association problem.

Bollonga February 20, 2013 06:25

I still don't find the problem. What does the white arrows in previous picture 1 mean? I don't hace those arrows in the other rectangles.

BrolY February 20, 2013 06:35

Blocking -> Associate -> Update Association.

If it doesn't work, you would have to redo all the association hand by hand.
Your problem sometimes occures if you delete curves or trim surfaces ... It's always better to disassociate a curve (Blocking -> Associate -> Disassociate from geometry -> Edges), and then reassociate.

Good luck ;)

Bollonga February 20, 2013 06:46

Quote:

Originally Posted by BrolY (Post 408960)
Blocking -> Associate -> Update Association.

That solved the problem! Far, you're the man.

Bollonga February 20, 2013 09:53

Quote:

Originally Posted by Bollonga (Post 408962)
That solved the problem! Far, you're the man.

I meant Alenxadre, merci beaucoup! Thank you too, Far!


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