AUTOGRID5 B2B Mesh grid lines mixed up in cascade

allenjohngeorge · October 5, 2018, 07:48

Hello,
I am trying to generate a mesh for a turbine blade cascade using Autogrid5. The grid lines in the B2B mesh generated are totally mixed up ( please see the images attached).

The grid lines does not follow any pattern and cut each other. If i dont choose the cascade option, then i am getting a proper mesh. I followed the procedures in the Numeca Autogrid5 advanced tutorial for cascade configuration. If anyone knows why this issue is there with cascade meshes, please help.

Thanks

Allen

Capture.jpg

Capture2.PNG

Hamidzoka · October 9, 2018, 07:22

Hi;
when you change the configuration to "cascade" you need to come back to row property and adjust the "periodicity" there.
Actually in case of linear cascade periodicity does not refer to number of blades anymore. This refers to pitch of the blade in m or mm depending on your chosen dimension system.

regards

allenjohngeorge · October 12, 2018, 08:58

Hi,

I have already done what you told, like adjusting periodicity in m or mm. I found the reason for this mixing up of grid lines. I have made the blade profile in NX10 using closed studio spline and imported it as iges file. Initially the strating point of spline was from leading edge. So the grid line mix up originates from leading edge. But as trial, I change the spline starting point to somewhere middle on the pressure surface and now the mesh mix up originates from the new point. So I think this is basically the issue with imported geometry. Even though I have chosen close contour spline in NX10, the imported iges file shows a line on the blade surface at the starting point of the spline. Now I need to find a way to remove this line on the blade surface

Hamidzoka · October 13, 2018, 02:10

You are right.
importing the airfoils in .igs format is a challenging task in Numeca mainly due to different modeling strategies that 3D modelers use to make airfoils.
I mean You can rarely find 2 different blade 3D geometries with the same modeling approach!
So I prefer .geomturbo since it is simple, straightforward and of course a little time-consuming. All you need is to have some points defining the airfoil and specify which is LE and which is TE.
Results is always satisfactory.

regards

October 5, 2018, 07:48	AUTOGRID5 B2B Mesh grid lines mixed up in cascade	#1
allenjohngeorge New Member Allen George Join Date: Dec 2013 Posts: 16 Rep Power: 12	Hello, I am trying to generate a mesh for a turbine blade cascade using Autogrid5. The grid lines in the B2B mesh generated are totally mixed up ( please see the images attached). The grid lines does not follow any pattern and cut each other. If i dont choose the cascade option, then i am getting a proper mesh. I followed the procedures in the Numeca Autogrid5 advanced tutorial for cascade configuration. If anyone knows why this issue is there with cascade meshes, please help. Thanks Allen Capture.jpg Capture2.PNG

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October 9, 2018, 07:22		#2
Hamidzoka Senior Member Hamid Zoka Join Date: Nov 2009 Posts: 282 Rep Power: 18	Hi; when you change the configuration to "cascade" you need to come back to row property and adjust the "periodicity" there. Actually in case of linear cascade periodicity does not refer to number of blades anymore. This refers to pitch of the blade in m or mm depending on your chosen dimension system. regards

October 13, 2018, 02:10		#4
Hamidzoka Senior Member Hamid Zoka Join Date: Nov 2009 Posts: 282 Rep Power: 18	You are right. importing the airfoils in .igs format is a challenging task in Numeca mainly due to different modeling strategies that 3D modelers use to make airfoils. I mean You can rarely find 2 different blade 3D geometries with the same modeling approach! So I prefer .geomturbo since it is simple, straightforward and of course a little time-consuming. All you need is to have some points defining the airfoil and specify which is LE and which is TE. Results is always satisfactory. regards