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aja1345 October 13, 2014 02:17

curve in airfoil
 
Hi Friends
I have a two-dimensional airfoil got into Gambit.
I wanted to know how to give it a curve?
Wells turbine is the subject of the my Thesis.
Note the curvature of the tip in the image below:


http://www.upload7.ir/imgs/2014-10/9...2347311853.jpg


http://www.upload7.ir/imgs/2014-10/3...0608280524.jpg
Thanks for your help

-mAx- October 13, 2014 02:36

display what you already have in Gambit

aja1345 October 13, 2014 13:08

Quote:

Originally Posted by -mAx- (Post 514004)
display what you already have in Gambit

Hi dear friend

Thanks .... note the following:

http://upload7.ir/imgs/2014-10/39760625907744765452.jpg

ghost82 October 13, 2014 13:15

I would:
- merge edges;
- create the face from merged edges;
- create a volume from sweeping the created face (+z direction);
- copy/rotate the volume aroung the central axis;
- create the central cilinder volume;
- merge all the volumes;
- if you need to "curve" external surfaces, create a cilinder volume and cut the blades;
- create external volume (air volume);
- subtract internal (solid) volume from external (air) volume.

aja1345 October 13, 2014 15:07

Quote:

Originally Posted by ghost82 (Post 514124)
I would:
- merge edges;
- create the face from merged edges;
- create a volume from sweeping the created face (+z direction);
- copy/rotate the volume aroung the central axis;
- create the central cilinder volume;
- merge all the volumes;
- if you need to "curve" external surfaces, create a cilinder volume and cut the blades;
- create external volume (air volume);
- subtract internal (solid) volume from external (air) volume.

hi dear friend

Thank you.
But as the following:

modelling:

We use the periodic boundary condition

http://www.upload7.ir/imgs/2014-10/7...9032798868.jpg

now,What should I do?

Thanks for your help

aja1345 October 13, 2014 15:21

Sorry,I have an other question:
Assuming that it is available vertexes of airfoil.

How to put vertexes of airfoil on the Cylinder(Cylinder that must be cut)?

Because the beginning, the points of airfoils are no curvature.

I'm confused!!!!!

-mAx- October 14, 2014 01:51

Quote:

Originally Posted by ghost82 (Post 514124)
I would:
- merge edges;
- create the face from merged edges;
- create a volume from sweeping the created face (+z direction);
- copy/rotate the volume aroung the central axis;
- create the central cilinder volume;
- merge all the volumes;
- if you need to "curve" external surfaces, create a cilinder volume and cut the blades;

--> from here you get your rotor as solid

Quote:

Originally Posted by ghost82 (Post 514124)
-create external volume (air volume);
- subtract internal (solid) volume from external (air) volume

--> you extract the fluid domain. The height of your external volume must be 12L, and move it to its right place
From here you have a full modell.
If you want to work with periodicity, you can split the model
http://www.upload7.ir/imgs/2014-10/7...9032798868.jpg


Quote:

Originally Posted by amir star (Post 514140)
Sorry,I have an other question:
Assuming that it is available vertexes of airfoil.

How to put vertexes of airfoil on the Cylinder(Cylinder that must be cut)?

Because the beginning, the points of airfoils are no curvature.

I'm confused!!!!!

I didn't get your point

aja1345 October 14, 2014 03:05

Quote:

Originally Posted by -mAx- (Post 514182)
--> from here you get your rotor as solid


--> you extract the fluid domain. The height of your external volume must be 12L, and move it to its right place
From here you have a full modell.
If you want to work with periodicity, you can split the model
http://www.upload7.ir/imgs/2014-10/7...9032798868.jpg



I didn't get your point

If u Imagine that I have the vertices coordinates related to airfoil, how can i fit or put the vertices on the rotor hob in order to coincide them.
I don't have any idea about it the software I used is Gambit ver.2.4
Thank you for Your help

-mAx- October 14, 2014 03:50

As ghost82 mentionned, you can merge all your tiny edges from airfoil, except both designing trailing edge.
Doing that you will still have one vertex (sharp angle from trailing edge)
You are also free to choose another one vertice: you can for example use the split edge tool: https://www.sharcnet.ca/Software/Gam...eom_edge_split

ghost82 October 14, 2014 05:43

1 Attachment(s)
Quote:

Originally Posted by amir star (Post 514140)
Sorry,I have an other question:
Assuming that it is available vertexes of airfoil.

How to put vertexes of airfoil on the Cylinder(Cylinder that must be cut)?

Because the beginning, the points of airfoils are no curvature.

I'm confused!!!!!

Hi,
here is what I mean:
When you merge the 2 volumes, after sweeping the airfoil, you will have the airfoil edge automatically projected to the cylinder (bottom-left image).
If you need to curve the airfoil create a new cilinder (red dotted) and cut the 3d blade, then delete the more external volume (black dotted).

aja1345 October 15, 2014 04:01

thank
 
hi my dear friends.

I can almost design Primary model with your guidance s but for merge edge I face a problem.

Edge merge method don't understand.how merge edge?

for this reason,i am doing edge and faces without merge but for Construct blade volume i face a problem and blade volume don't Construct correctly,attention to bellow image:


http://upload7.ir/imgs/2014-10/50916681304851603069.png

According to the following image, For merge,two Later edge don't consider but get following error:

http://upload7.ir/imgs/2014-10/64768975799944540504.jpg

too,total edges consider but again get following error:

http://upload7.ir/imgs/2014-10/22990953390987136913.jpg

vertexes of airfoil figure Before construct volume:

http://upload7.ir/imgs/2014-10/50788530178386686027.jpg

vertexes of symmetrical airfoil:

http://www.upload7.ir/imgs/2014-10/1...8650485083.jpg

edge and faces of symmetrical airfoil:

http://www.upload7.ir/imgs/2014-10/4...5931525284.jpg

http://upload7.ir/imgs/2014-10/80986115583054478951.jpg

Blade figure Before construct volume:

http://www.upload7.ir/imgs/2014-10/0...6905548992.png

figure of modeling:

http://upload7.ir/imgs/2014-10/06065188234221131607.jpg

Thank you for allocating your time.

-mAx- October 15, 2014 05:02

follow instructions from ghost82: work only with volumes (not surfaces)

ghost82 October 15, 2014 07:00

1 Attachment(s)
Merge edges!
see here:
https://www.sharcnet.ca/Software/Gam...ide/mg0203.htm

Default is split edge, so right click on the split edge button to select merge edges, select 2 edges at a time and merge them.
I suggest to leave 2 vertices to easily mesh geometry (see picture).

PS: I'm automatically updated when somebody reply to this thread so no need to send private messages :P

aja1345 October 15, 2014 09:37

hi,thanks

In some cases when I do merge some edges by the chance it merges and virtual edge is created instead of the real edge. is there any rule for merging that i don't follow it or these kind of virtual edges don't create any problem in further processing steps?


http://www.upload7.ir/imgs/2014-10/2...7537969885.jpg


http://www.upload7.ir/imgs/2014-10/8...6256172841.jpg


virtual edges:


http://www.upload7.ir/imgs/2014-10/4...5347637087.jpg


thank for your helps.

aja1345 October 20, 2014 16:00

Dear Friends,
First, I would like to thank you for all your help and inform you that I have finally made my intended model.



http://www.upload7.ir/imgs/2014-10/0...1854107784.jpg





In my model, I want to make the upper airfoil cord bigger than the buttom one.

http://www.upload7.ir/imgs/2014-10/1...5700652005.png

I would appreciate it if you could kindly give me your advice. if you could send me a visual, H would be thankful.
Best,
Amir

-mAx- October 21, 2014 02:20

if you modify the design of your airfoil, you will have to redo everything.
But you can use your previous journal file to "automatically" rebuild your geometry.
https://www.sharcnet.ca/Software/Gam...#menu_file_run

if you only want to extend your domain, the sweep tool should be suitable

aja1345 October 21, 2014 17:25

Quote:

Originally Posted by -mAx- (Post 515269)
if you modify the design of your airfoil, you will have to redo everything.
But you can use your previous journal file to "automatically" rebuild your geometry.
https://www.sharcnet.ca/Software/Gam...#menu_file_run

if you only want to extend your domain, the sweep tool should be suitable

hi,

thanks

Yes, but I my problem is making the blade.
Dash line is for previous model.
New model is red lines that I do not know that model.


http://www.upload7.ir/imgs/2014-10/3...9287448245.png


In the meantime I've deleted the journal file and have the file (dbs).
Until now I did not work with journal file.

From First modeling, but how do I create blade?

Such post #10 with pictures to explain me,I would be thankful.

Thank you for allocating your time.

-mAx- October 22, 2014 01:52

Quote:

Originally Posted by amir star (Post 515425)
From First modeling, but how do I create blade?

How did you create the blade from your previous model?
:rolleyes:

aja1345 October 22, 2014 04:07

hi my dear friend

i have created the blade with sweep tool, and so with volume split tool by face.


Procedure is as follows:



http://www.upload7.ir/imgs/2014-10/5...5036733396.jpg


http://www.upload7.ir/imgs/2014-10/3...9574709609.jpg


sweep airfoil(face):


http://www.upload7.ir/imgs/2014-10/4...6873875991.jpg

create new cylinder:

http://upload7.ir/imgs/2014-10/47856518231227698890.png


blade volume subtract volume 6:



http://upload7.ir/imgs/2014-10/18138432192410606333.png




create edges for Faces:



http://www.upload7.ir/imgs/2014-10/1...2672712003.jpg



http://www.upload7.ir/imgs/2014-10/1...0007975334.jpg


http://www.upload7.ir/imgs/2014-10/1...2621827120.jpg


created faces:



http://www.upload7.ir/imgs/2014-10/7...6746482722.jpg


volume split tool by created faces:




http://www.upload7.ir/imgs/2014-10/8...9194383326.jpg

continue.....

aja1345 October 22, 2014 04:08

deleted volumes:


http://www.upload7.ir/imgs/2014-10/9...1082369121.jpg


http://www.upload7.ir/imgs/2014-10/5...6083214863.jpg


http://www.upload7.ir/imgs/2014-10/5...3427838378.jpg


Thank you for allocating your time.


I really do not know what to do for the new model.Now Here,
I do not think the sweep tool is efficient( in Third picture Previous post).


best,


Amir


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