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Old   October 13, 2014, 01:17
Question curve in airfoil
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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:






Thanks for your help
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Old   October 13, 2014, 01:36
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display what you already have in Gambit
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Old   October 13, 2014, 12:08
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Quote:
Originally Posted by -mAx- View Post
display what you already have in Gambit
Hi dear friend

Thanks .... note the following:

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Old   October 13, 2014, 12:15
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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.
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Old   October 13, 2014, 14:07
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Quote:
Originally Posted by ghost82 View Post
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



now,What should I do?

Thanks for your help
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Old   October 13, 2014, 14:21
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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!!!!!
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Old   October 14, 2014, 00:51
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Quote:
Originally Posted by ghost82 View Post
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 View Post
-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



Quote:
Originally Posted by amir star View Post
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
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Old   October 14, 2014, 02:05
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Quote:
Originally Posted by -mAx- View Post
--> 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




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
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Old   October 14, 2014, 02:50
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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
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Old   October 14, 2014, 04:43
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Quote:
Originally Posted by amir star View Post
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).
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File Type: jpg cfd.jpg (25.8 KB, 7 views)
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Old   October 15, 2014, 03:01
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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:




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



too,total edges consider but again get following error:



vertexes of airfoil figure Before construct volume:



vertexes of symmetrical airfoil:



edge and faces of symmetrical airfoil:





Blade figure Before construct volume:



figure of modeling:



Thank you for allocating your time.
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Old   October 15, 2014, 04:02
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follow instructions from ghost82: work only with volumes (not surfaces)
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Old   October 15, 2014, 06:00
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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
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Old   October 15, 2014, 08:37
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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?








virtual edges:





thank for your helps.
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Old   October 20, 2014, 15:00
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Dear Friends,
First, I would like to thank you for all your help and inform you that I have finally made my intended model.









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



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
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Old   October 21, 2014, 01:20
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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
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Old   October 21, 2014, 16:25
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Quote:
Originally Posted by -mAx- View Post
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.





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.
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Old   October 22, 2014, 00:52
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Quote:
Originally Posted by amir star View Post
From First modeling, but how do I create blade?
How did you create the blade from your previous model?
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Old   October 22, 2014, 03:07
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hi my dear friend

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


Procedure is as follows:









sweep airfoil(face):




create new cylinder:




blade volume subtract volume 6:








create edges for Faces:













created faces:






volume split tool by created faces:






continue.....
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Old   October 22, 2014, 03:08
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deleted volumes:











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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