Turbogrid or CFX-Post Problem?!

Safasml · March 25, 2020, 13:21

Hi
I generated a 3d blade of an axial turbine in the design modeler, meshed it using turbogrid and solved the flow using CFX. Now, I want to export the pressure at a specific section of the blade, but only on the airfoil surfaces. I decided to make a polyline using the intersection of the blade surface and a plane at that specific height of the blade. The point is that I need the pressure at the lower and higher surface of the airfoil separately. So, I should make that polyline using the intersection of the high (or low) blade surface (I mean one side of the blade) and the mentioned plane. But the problem is that the high blade side doesn’t completely cover the higher surface of the blade (look at the figure) and also the lower side is the rest of the higher one. So, both of them can’t be useful to me. What should I do?

AtoHM · March 25, 2020, 15:40

This can happen in TGrid, actually I dont know if one can precisely set the position where the split occurs. I always extracted my values at the whole polyline and split the parts up by their actual coordinates, like looking at the z-coordinate in your case. Maybe you can extract the streamwise position also and split by that. But that might not be the optical right spot as well? Just some thoughts.

Opaque · March 25, 2020, 17:32

What version of Turbogrid are you using?

In a recent version, the low blade and high blade are split into regions named

<name > LOWBLADE GEO LOW
<name > LOWBLADE GEO HIGH
<name > HIGHBLADE GEO LOW
<name > HIGHBLADE GEO HIGH

You can read about them in the documentation

Safasml · March 26, 2020, 02:18

Dear AtoHM,
Thanks for your reply. Exporting the results is a part of an automatic and iterative procedure. So I can’t split the results manually. The values should be split first and then written in a (for example) text file.

Dear Opaque,
I use ANSYS 19 and the turbogrid just has LOWBLADE and HIGHBLADE. When they are imported to CFX-Pre (and CFD-Post) they are changed to BLD LOW and BLD HIGH.

So maybe there are other ways I can use them.

How can I define a surface on the higher/lower side of the blade? I tried using the user surface in CFD-Post, but it wasn’t exactly what I want. I define them in the design modeler but they aren’t exported to turbogrid and CFD-Post. So any idea to define these surfaces by myself?

March 25, 2020, 17:32		#3
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	What version of Turbogrid are you using? In a recent version, the low blade and high blade are split into regions named <name > LOWBLADE GEO LOW <name > LOWBLADE GEO HIGH <name > HIGHBLADE GEO LOW <name > HIGHBLADE GEO HIGH You can read about them in the documentation __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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March 25, 2020, 15:40		#2
AtoHM Senior Member M Join Date: Dec 2017 Posts: 703 Rep Power: 13	This can happen in TGrid, actually I dont know if one can precisely set the position where the split occurs. I always extracted my values at the whole polyline and split the parts up by their actual coordinates, like looking at the z-coordinate in your case. Maybe you can extract the streamwise position also and split by that. But that might not be the optical right spot as well? Just some thoughts.

March 26, 2020, 02:18		#4
Safasml Member Join Date: Oct 2017 Posts: 35 Rep Power: 9	Dear AtoHM, Thanks for your reply. Exporting the results is a part of an automatic and iterative procedure. So I can’t split the results manually. The values should be split first and then written in a (for example) text file. Dear Opaque, I use ANSYS 19 and the turbogrid just has LOWBLADE and HIGHBLADE. When they are imported to CFX-Pre (and CFD-Post) they are changed to BLD LOW and BLD HIGH. So maybe there are other ways I can use them. How can I define a surface on the higher/lower side of the blade? I tried using the user surface in CFD-Post, but it wasn’t exactly what I want. I define them in the design modeler but they aren’t exported to turbogrid and CFD-Post. So any idea to define these surfaces by myself?