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-   -   Modeling Propeller Geometry in STAR CCM+ 3D-CAD (http://www.cfd-online.com/Forums/star-ccm/102113-modeling-propeller-geometry-star-ccm-3d-cad.html)

tava.amitava May 22, 2012 13:36

Modeling Propeller Geometry in STAR CCM+ 3D-CAD
 
Hi,

I am trying to model a propeller geometry using the 3D-CAD module of STAR CCM+. I have offset data at various sections of the propeller blade at different distances from the hub (or shaft). I could create the profile of the section using spline line. But I am not sure how can I put together all such cross-section lines and generate a surface. I could only see an Extrude option available.

Wanted to conform whether it is possible to generate such geometry using the 3D-CAD module or I have to use third party CAD software to do this.

Thanks,
Amitava

f-w May 22, 2012 14:09

Select multiple sketches (each defining a profile at a different station) and then bring up the right-click option. The option to create a loft will then be available.

tava.amitava May 22, 2012 14:24

Thank you for your reply. I am very new to this. Could you please guide me little more. My profiles should be separated by a certain distance. When I try to create new sketch on XY-Plane, it starts creating the profile at the same place where the first profile is. How do I move my profile curves at appropriate position .

http://i.imgur.com/xJCGS.png

abdul099 May 22, 2012 16:17

Right-click on your XY-Plane in the tree on the left. There should be an option to create a transform sketch plane. For this plane you can specify offsets or orientations with respect to the other planes. Use this plane for the next sketch and create a new transform sketch plane for the next sketch and so on.

You should take care that your sketch is a completely closed loop. Don't know if you already know that, but in your picture it seems to be an open loop.

tava.amitava May 24, 2012 14:22

Quote:

Originally Posted by abdul099 (Post 362545)
Right-click on your XY-Plane in the tree on the left. There should be an option to create a transform sketch plane. For this plane you can specify offsets or orientations with respect to the other planes. Use this plane for the next sketch and create a new transform sketch plane for the next sketch and so on.

You should take care that your sketch is a completely closed loop. Don't know if you already know that, but in your picture it seems to be an open loop.

Hi,

Thank you Abdul for your insightful comment. I believe I can prepare the propeller model now. However, as you mentioned, in each new transform sketch plane (which are shifted and rotated as per Propeller Rake, Section height (r/R) and Skew angles) I need to create my profile based on the Offset Table data. Is there any way I can import these into the appropriate transform sketch plane.

Thanks

abdul099 May 24, 2012 15:24

I'm afraid I don't know any way to import data directly to a sketch. You might be able to do it with a Java macro, but that's no convenient way.
Maybe somebody else know a solution, or drop a line to the CD-adapco support. When there's a simple way, they should help you pretty fast.

f-w May 24, 2012 20:13

Check out the help file:
Modeling Geometry > Using 3D-CAD > Importing Geometry into 3D-CAD > Importing 3D Curves From a Spreadsheet

tava.amitava May 25, 2012 10:45

Hi,

Thank you for your suggestions. I am able to make some progress based on your help.

I have created CSV files with (X,Y,Z) coordinates after appropriately applying rake, skew and pitch translation and rotation. I am able to import these profiles to Star CCM+. Now I needed some guide wire to generate smooth blade surface. So I joined the leading edge and trailing edge points to create the guide wire. However, I am only able to create a loft only if the guide wires are between two profiles. If the guide wire extends outside two profile then lofting gives me error message that the geometry is open.

Also, I couldn't create the top portion of the propeller using loft.

I need the guide wire to be a spline and not a straight line between two profiles.

Could you please tell me how can I break the guide wire into segments between each profile after I import the whole wire.

I find it difficult to explain, but hope you understand what I am looking for. See attached picture for my current model.

http://i.imgur.com/d25xy.png

http://i.imgur.com/nUfQh.png

Thanks for your help.

f-w May 25, 2012 12:31

1 Attachment(s)
No easy way of doing this with the limited functions of Star-CCM+ 3D-CAD tools, this is because once you import the curves, you can't do shit with them. The best way is to do this in an external CAD software. If that's not an option, here's the hard way:

1) Make sure the points (in the .csv) defining your guide curve intersect, exactly, the LE of each each profile.
2) To model the tip, model another profile with a very small, but finite area, and then apply a fillet. Attached is a picture that visualizes this step.

abdul099 May 25, 2012 14:30

To model the propeller tip can be pretty hard even when using a "full" 3D CAD. I experienced some issues when I was modelling wings and winglets, but it was using Solidworks. And Star-ccm+ is a CFD package, no 3D CAD. So it might have too much limitations to do the job in an easy way.
When it's somehow possible for you, I recommend to model it in a dedicated 3D CAD instead of Star-ccm+. When that's not acceptable, I wish you a lot of luck (you will need it).


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