[aco92]

Hello Numeca experts,

I am trying to import a simple CAD model of a Naca Blade (made in Creo/ProE) into Autogrid. Unfortunately I keep getting errors.
I really tried everything that came into my mind but I am still not able to do it.

First of all I was able to import geometries into AutoGrid in the tutorials, so I am basically familiar with the process.

I also went through related topics in this forum and couldn't find a solution.

After linking hub, shroud, blade, LE & TE and specifying the row properties I click on Intialize Topology and get the following error:

Maximum expansion ratio in flow paths: 1.55
******* Generate Row 0 ********
Error in row 1 :Main Blade Geometry Not Fully Defined
No intersection between Hub and Main Blade
ERROR: intersection problem between:
row 1, Main Blade
and row 1_flowPath(0)

!! BLADE TO BLADE MESH NOT INITIALIZED !!
!! CHECK YOUR GEOMETRY !!
!! AND PRESS Initialize Topology and Grid Points Distribution !!
!! OR Generate B2b !!

When I do the geometry check I also get an error: Blade Body not defined
Increasing the sewing tolerance didn't change anything. The units are also fine.

I am pretty sure the problem lies within the blade and not the hub&shroud curves,
since I also tried to draw them manually in the import window, which worked with the blade from the tutorial file, but not here.

I created the blade in Creo and tried to save it both in the .IGS and parasolid format.
The blade was modelled by creating two splines with a point distribution for suction and pressure side and was then simply extruded into 3D.
I can't see anything that could have gone wrong in this process.

model in import window.jpg

model in import window2.jpg

meridional view in autogrid.jpg

3d view in autogrid.png

I attached some pictures so you can understand everything better.

Thanks for your help!

[DarylMusashi]

Dear aco,

what you have done so far looks promising. Usually the hub and shroud define cylinders, but in your case you are going to do a cascade configuration as hub and shroud define planes (seen from your figure 4). May I ask if you have defined your project correctly? During project initiation you need to select "Cascade".
Secondly, in the 3D solid view (figure 4 again) you can check if the blade really intersects completely the hub. AutoGrid doesn't think so at the moment, even if the blade seems to intersect the hub in the meridional view.
Another option is to extend your blade in the CAD model and link it again. Secondly, you can try to further extend the blade in AutoGrid. In the top left panel open the tree structure until you see the main blade, right click on it, Geometry, Expand. Under hub treatment you have several expansion possibilities.

Finally, you missed out the best part of AutoGrid. After you imported the geometry successfully don't press "Initialize" but start the RowWizard. This leads you with a few steps through the mesh generation process and you get a very good initial mesh. If you wish you can further improve it manually.

Kind regards,
Holger

[aco92]

Hello Holger,

thank you very much for your quick reply!

You are right I am simulating a compressor stator cascade. I am also trying to do it in 2D which I intend to control later by setting the no. of flow paths to 2.

I selected "Cascade" in the initialization, so this shouldn't be the problem.

But I think I found the location of the intersection problem (see pictures). It was tricky to see since it's only visible before setting the row properties (periodicity). The last picture shows the 3d view after setting the row properties.
However I still don't know how to solve it.

How can I manipulate the width of the computed hub plane (green plane)?
I already tried to rotate my blade by 45° in my CAD model but then again I have a intersection problem (this time at the LE).

Thank you for your efforts!


3d view_1.jpg

3d view_2.png

3d view_3.png

3d view_after row properties.png

[DarylMusashi]

Dear aco,

firstly, please reduce the Sewing Tolerance of your blade, which is accessible from the top left menu: Row X, Blades, Main Blade, Geometry, Expand.

Referring to the 3D solid pictures you attached, you can also try to re-position the trailing edge in minus y direction. As a result the trailing edge will be located near the lowest y-coordinate of your blade.

Kind regards,
Holger

[aco92]

Hello Holger,

yes that's basically how I managed to solve the issue. I just didn't get to write it down here yet.

The problem was that my TE line that I had in my CAD model didn't correspond to the lowest Y-coordinate of my blade. Numeca however defines the hub plane through the LE & TE that the user links. This lead to the protruding part of the TE that can be seen in the pictures above.

I solved the problem by redefining my CAD model in order to get a TE line that also represents the lowest value of my blade geometry. In the picture you can see the upper line, which is my original TE and a second lower line which I now used as TE.

1.jpg

After doing this I still had the problem until I reduced the sewing tolerance of my blade as you already described above.

Thanks again for the help!

Best Regards

Aco