I need to perform some CFD analysis on airfoil and wing and want to create the 3D model in CATIA. I have NACA airfoil which has around 400 points. Manually using the spline tool in part file is not a very efficient option, which I've tried as well but still not very good spline.
I have tried using the GSD_PointSplineLoftFromExcel.xls option, it doesn't give me a very good spline.
I'm also trying working it in Digitized Shape Editor by using the Cloud Import toolbar but can't really make spline from the points so imported.
I'm trying to find other ways to do this. Has anyone worked on it and if possible send me some reference links?
Thanks
You can find the DAT files of different airfoil available in different website. Download DAT file of the specific airfoil and import it straight away in CATIA. I did the same thing.
And what about the spline? My problem is more with the spline generation. Simply using the spline tool in CATIA does not create very nice spline, atleast in my case.
hi,
I suggest you watching this video\\ https://www.youtube.com/watch?v=J7TqxeTuK4U
It helped me to desing H-Darrieus wind turbine.
What exactly do you mean by "I have tried using the GSD_PointSplineLoftFromExcel.xls option, it doesn't give me a very good spline" ?
There is a number of issues to consider when importing geometry in Catia and other CAD-systems:
1. Airfoil geometry is usually given in nondimensional coordinates (x/l & z/l). This means that X ranges from 0 to 1, and Z has an even smaller range, depending on thickness ratio. The default dimension for length in CATIA is mm, with a resolution of 1/1000 mm. So with nondimensional coordinates, you have at most three digits of resolution, and much less in thickness direction, which is clearly not enough. Solution: Scale your coordinates up before import by at least a factor of 1000.
2. Even with higher resolution, there is limited accuracy. A spline is a mathematical function forced to go through all your points. This introduces some mathematical oscillations. Solution: You need to smooth the initial spline. The result will deviate from some of your imported points very slightly, but produce a smooth curve that is more suitable for CFD (This is the digital equivalent to hand sanding a W/T model until the surface feels smooth!). You can do a curvature analysis to both curves to see the improvement. You also have to keep in mind that your initial geometry is never perfectly accurate either, due to a limited number of digits and other factors. A very large number of points doesn't necessarly mean the data is very precise...
3. When creating splines, it is important to make a single spline which begins and ends at the trailing edge. Don't do separate splines for upper and lower side, this will result in bad geometry at the nose.
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