# [ICEM] 2D NASA Rotor 67 Blade outer profile (boundary)

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June 27, 2010, 12:59
2D NASA Rotor 67 Blade outer profile (boundary)
#1
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t_shirt
Join Date: May 2010
Posts: 8
Rep Power: 8
Hi All,

I just have two question;
how can we create 2D blade airfoil outer boundary as shown in attached pic?

Basically it is a periodic boundary is there any mathematical relation or equations if yes pls let me know where i can get it?

I am using ICEM CFD, what will be step i will follow to create for meshing here?

Thank you and Regards,
Attached Images
 2D-Airfoil.jpg (27.8 KB, 128 views)

 June 28, 2010, 11:24 Periodic sides. #2 Retired from CFD Online     Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,660 Blog Entries: 1 Rep Power: 38 As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane. But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.

July 15, 2010, 14:23
Script File in ICEM CFD
#3
Senior Member

Saima
Join Date: Apr 2009
Posts: 140
Rep Power: 9
Hi PSYMN,

I am writing script for ICEM CFD. Some where in my geometry i split edge at a point, but when i am writing script it takes as a coordinate like:

ic_hex_split_edge 55 43 0 1.68349 8.84739 0

Instead of taking coordiante i want to assign a point i have a point on the same position like pnt.06 at (x,y,z): (1.68349, 8.84739, 0)

but i dont know how i can write it in this line.

Kindly let me know. I will be greatfull of u.

Thank you

Quote:
 Originally Posted by PSYMN As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane. But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.

 July 15, 2010, 20:38 Split Method Prescribed Point #4 Retired from CFD Online     Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,660 Blog Entries: 1 Rep Power: 38 Hey Samia, You are using the wrong command... Under Split Edge, you will see a "Split Method" option. The default methid is "Screen Select" which uses an XYZ location. Even if you use it to select a point, it really just gives the location of the point (as you saw). However, if you choose the "Prescribed point" Split Method, it will use the point name (which is what you want because it is much more parametric). SplitBlock_PrescribedPoint.gif The command should look something like this... ic_hex_split_grid 22 38 PointName.21 m POINTS CURVES SURFS SOLID

July 16, 2010, 12:28
#5
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Saima
Join Date: Apr 2009
Posts: 140
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Thank you PSYMN,

Actualy if u see this you tube web site for airfoil http://www.youtube.com/watch?v=EknKV...eature=related

Here instead of using "Automatic Linear" option under edit edge command for overlaping block+airfoil wall, i am using linear or spline option. That command generates it.

I dont know why automatic linear option does not working in my case.

Kindly suggest me the way make it automatic or atleast give point at this stage.

Regards,

Quote:
 Originally Posted by PSYMN Hey Samia, You are using the wrong command... Under Split Edge, you will see a "Split Method" option. The default methid is "Screen Select" which uses an XYZ location. Even if you use it to select a point, it really just gives the location of the point (as you saw). However, if you choose the "Prescribed point" Split Method, it will use the point name (which is what you want because it is much more parametric). Attachment 4078 The command should look something like this... ic_hex_split_grid 22 38 PointName.21 m POINTS CURVES SURFS SOLID

Last edited by Saima; July 16, 2010 at 12:43.

 July 16, 2010, 16:10 Oops... #6 Retired from CFD Online     Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,660 Blog Entries: 1 Rep Power: 38 Oops, sorry, i read it too quickly and thought you meant split block. Split edge doesn't have a point selection option (although it does say to select a point, I will fix that...) What you would need to do is use a command like ic_geo_pick_location... (you can look it up int he programmers guide, you would need to actually type it into the replay script) This would give you output in terms of x, y, z for a particular point name, then you would set those to \$X, \$Y, and \$Z which you would use in the split edge line... We could discuss that more if that is what you really want to do... However, if you just want to split automatic like I did... That uses the Edge distribution to determine the linear edge split locations. If it is not working for you, it is probably because you have not set your edge parameters so your edge only has nodes on either end and there are no locations for the automatic split edge to use... Simon

July 20, 2010, 17:38
#7
Senior Member

Saima
Join Date: Apr 2009
Posts: 140
Rep Power: 9
Hi PSYMN,

But i am still not able to do command which told me.
I have commands in script file, after using Block----edit edge----split type....Method:linear

ic_hex_split_edge 53 41 0 0.52817 7.82042 0
ic_hex_split_edge 55 43 0 1.68349 8.84739 0
ic_hex_split_edge 49 55 0 3.24686 7.10986 0
ic_hex_split_edge 47 53 0 1.83217 6.03755 0

Now i want to edit my script in the manner it picks point name instead of coordinate like:

ic_hex_split_edge 53 41 0 pnt06
since pnt 06: 0.52817 7.82042 0

But this is not working. I tried urs one after giving
ic_geo_pick_location 0.52817 7.82042 0

it give me error does not recognized "0".

I tried with \$ too but it is not working and secondly how it know i am picking location for spliting edges 53 and 41.

Thank you

but my script is not working

Quote:
 Originally Posted by PSYMN Oops, sorry, i read it too quickly and thought you meant split block. Split edge doesn't have a point selection option (although it does say to select a point, I will fix that...) What you would need to do is use a command like ic_geo_pick_location... (you can look it up int he programmers guide, you would need to actually type it into the replay script) This would give you output in terms of x, y, z for a particular point name, then you would set those to \$X, \$Y, and \$Z which you would use in the split edge line... We could discuss that more if that is what you really want to do... However, if you just want to split automatic like I did... That uses the Edge distribution to determine the linear edge split locations. If it is not working for you, it is probably because you have not set your edge parameters so your edge only has nodes on either end and there are no locations for the automatic split edge to use... Simon

 July 21, 2010, 14:26 Sample Script #8 Retired from CFD Online     Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,660 Blog Entries: 1 Rep Power: 38 Samia, you took me completely backwards... the pick location should be applied against the point name (not the location). That would then give the location that you could use in the actual command (with the \$x, \$y, \$z)... Try inserting something like this for each split edge command... (example script supplied to me by Jari) set name pnt.00 ;# point must exist set loc [ic_geo_get_point_location \$name] set x [lindex \$loc 0] set y [lindex \$loc 1] set z [lindex \$loc 2] ic_hex_split_edge 21 25 0 \$x \$y \$z Hope that helps. Also, you asked about the number 0 after the two vertex numbers (e.g. edge 21 25 0). This means that it is between vertex 21 (start vertex) and 25 (end vertex). "0" is the first split, if the number were 1, it would mean that this split is the second between the vertex 21 and vertex 25. I am not sure why this wasn't included in the Programmers guide. I will ask them to fix that.

July 22, 2010, 11:44
#9
Senior Member

Saima
Join Date: Apr 2009
Posts: 140
Rep Power: 9
Thank you so much Simon.

It is working well. I really appreciated.

Best Regards,
Saima

Quote:
 Originally Posted by PSYMN Samia, you took me completely backwards... the pick location should be applied against the point name (not the location). That would then give the location that you could use in the actual command (with the \$x, \$y, \$z)... Try inserting something like this for each split edge command... (example script supplied to me by Jari) set name pnt.00 ;# point must exist set loc [ic_geo_get_point_location \$name] set x [lindex \$loc 0] set y [lindex \$loc 1] set z [lindex \$loc 2] ic_hex_split_edge 21 25 0 \$x \$y \$z Hope that helps. Also, you asked about the number 0 after the two vertex numbers (e.g. edge 21 25 0). This means that it is between vertex 21 (start vertex) and 25 (end vertex). "0" is the first split, if the number were 1, it would mean that this split is the second between the vertex 21 and vertex 25. I am not sure why this wasn't included in the Programmers guide. I will ask them to fix that.

June 23, 2012, 20:21
#10
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venkatesh
Join Date: May 2012
Posts: 93
Rep Power: 6
Quote:
 Originally Posted by PSYMN As a starting point, I usually draw a curve from the stagnation point thru midpoints along the blade all the way to the tip. This is my initial shape. Then I copy that up (or down) by half the blade spacing. Then I add a tangential curve from the inlet plane to the front of the curve and a second one from the trailing edge to the outlet plane. But in the end, I usually just let the smoother move those sides. The solver doesn't really care about the shape or location of those periodic curves (but the spacing is important). The smoother will move those nodes to optimize quality and maintain periodicity.
Hi Simon,

I have created the Periodic boundary curve (Figure 1) as explained in your post. But I dont know to make it as smooth curve (Figure2). Could you please suggest me some idea to get a smooth periodic curve.

Regards,
Venkat
Attached Images
 ICEM_periodicity.jpg (46.7 KB, 26 views) 2D-Airfoil.jpg (27.8 KB, 23 views)

 June 24, 2012, 00:35 #11 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,285 Blog Entries: 6 Rep Power: 43 Draw few points on one of the periodic curve and then join them with nurbs option. Delete the original curve and copy newly create curve to other periodic location. Done

 June 24, 2012, 07:25 #12 Member   venkatesh Join Date: May 2012 Posts: 93 Rep Power: 6 Hi Far, Thanks for your reply. I am not able to find Nurbs option in ICEM CFD. Do you mean spline option.

 June 24, 2012, 08:17 #13 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,285 Blog Entries: 6 Rep Power: 43 Yes. It is

 June 24, 2012, 09:12 #14 Member   venkatesh Join Date: May 2012 Posts: 93 Rep Power: 6 Once again thanks Far

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