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How to Model an Airfoil

Manny Marquez - Wednesday, March 12, 2014
Last week, on my flight back to Chicago, I always find it more enjoyable for long flights especially to have the window seat for a few reasons. Of the few things that I enjoy, one is watching how thrust is pushed in between the turbine blades of the engines and how the wing flaps pivot when used for breaking as the plane lands.

When I had landed, a thought came to me; and that was that I have never seen a turbine engine airfoil blade or wing model in Solid Edge. So I took it upon myself to do some research on how I would model airfoils. I came across some interesting web sites that explain the whole explicit mathematical functions used for 2D curve definition for airfoil design; very fascinating however, I just wanted the basics.

 

 

 

Here is the basic anatomy of a blade; you have root type, root width, root height, and airfoil height.


For many years, research and studies have been conducted on airfoil blades and also on the performance of wing design aerodynamics. Shown below is an airfoil generator for blades that I found online.

As you can see by entering the appropriate values you should be able to generate an airfoil based on you requirements.

Geometry Airfoil Generator Example: 

 

 

After generating the foil you have two options, either to create a DAT file or simply copy and paste the X,Y,Z coordinates to your excel.

I chose to just simply copy and paste directly to Excel. Notice A=X B=Y C=Z, in some cases if you are creating a simple airfoil you may only get XZ coordinate values. If that is the case you need to insert a cell and enter zero for Y as shown in this case.

 


 

 1. Before you start anything you will need to model up the root type, make this part in ordered. Surface modeling works best on the ordered mode. I downloaded a CAD model from GrabCAD website. If you have the time to model, a basic shape like shown below, make sure the XYZ origin is setup correctly. Therefore, when creating the airfoil via the Solid Edge curve by table option, it is placed correctly on the root top surface.

 

 

2. Next click on the curve by table option. It is located in the surfacing tab on the curves group.

 

 

3. Click on browse, then find the excel files.

 



4. Select finish. Notice the 2D airfoil automatically sets on the origin.

 

 

5. By clicking on the edit points data step, the Excel sheet will open. If there should be a need to modify the XYZ points manually you will be able to do so at this step. Click finish when you are satisfied.

 

 

6. Another option is to set the curve fit and curve end conditions.

 



7. On the next step, we are going to create two User coordinates systems.
Under the surface tab, find coordinates system on the planes group. This will allow us to place new airfoils at any point in space.

Select (key-in (relative to another Coordinates system)

 



8. Enter 3 on the (Y), next then preview and then finish. Repeat the same step for the second UCS, except enter 6 for (Y).

 

You model should look like this.

 

 

Now, we can continue since we have created the UCS to place the airfoils.

9. Repeat the same steps for the second airfoil. You may have as many airfoils as you wish- usually that varies on how
complex your blade may be. For this example, I will only be using three airfoils.

 

10. This time before clicking on finish, select the second coordinate system (the names may vary).

 

 

Repeat for last Airfoil.

 

 

Your model should look like this: Root with all three USC in place.

11. We are now going to create a BueSurf. This will create the outer shell for each airfoil, thus creating the turbine blade.

12. Click on the BlueSurf command, located on the surfaces group.

13. Select the first airfoil sketch.

 

 

 

Make sure the cross section vectors are consistent with the other geometery.

14. Select on the second airfoil sketch, notice again the vectors are consistent with the first selection.

 

 

15. You model should look like this.

 

 

16. Continue on with the selection

 

 

The overall blade has been constructed, we will now add rotation to the blade. Some blades have more complex geometry, I’m only using three airfoils to crreate a simple blade

17. Select the origin, and then click on edit definition.

 


 

 

18. Click on the orientation step.

 

 

19. Enter 25˚ for the Y direction.

 

 

Notice the foil is now 25˚ about the Y

20. Repeat the same step for the last coordinate system. Enter 30˚

 

 

21. You have completed this turbine blade using a geometry generator with BlueSurf. I hope you enjoyed it.

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