Swept Y (laminar ducting)

[roughwood]

I am trying to design inlet ducts for a small RC jet I'd like to start building in about a year. They will look like a Y basically, 2 inlets 1 outlet. The cross sections will be practically circular at the inlet and outlet. My trouble is the area where the left and right inlets merge into the one area in front of the engine. Does anyone know how to get 2 cross sections to join into 1? The cross sectional area must stay constant throughout, both the right and left inlets must add to the same as the area where they merge, hopefully I made that understandable.

I figure swept is my best option, but I cannot for the life of me figure out how to get 2 seperate cross sections to join into one. I figure someone in here must design complex laminar fluid flow ducting. By laminar, basically I mean the ducting (the swept or what have you) must be smooth continuose and non abrubt in order for the flowing air not to become turbulent.

Keith Young
keith.a.young@comcast.net
Walway Enterprises
UG Tool Design

 

[Xwheelguy]

If you have just 2 section strings & no guides, try using Through Curves & assign continuity as needed. Make sure the red arrows point in the same direction if at all possible. Only use Swept if you have a specific path that your feature must follow because Swept doesn't allow you to assign continuity constraints.

If you have the documentation installed, it does a fairly good job of explaining the concepts of how to pick the section strings & aligninment methods for both Through Curves & Swept.

Hope this helps a little.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[cowski]

Also, look up 'corner feature' in the modeling help (I'm on NX2 so that's the version I'm referring to). It is called 'corner feature' in the help file but 'transition' in the free form menu (I guess the tech writers and developers weren't talking that day). I can't claim to have a lot of experience using it but it looks like it would do what you want.

 

[roughwood]

NK, it is 2 sections that become one, picture a Y adapter etc. The reason I mentioned Swept is because there is a constant area option somewhere in there, which keeps its cross sectional area constant.

cowski, yes I recall that there is such a command in NX2 now that you mention it. Do you know of a way in NX1? I suppose since I am not far at all on this ducting I could start over in NX2 and try corner feature. Do you know if there is a way to keep cross sectional area constant in this command?

Keith Young
keith.a.young@comcast.net
Walway Enterprises
UG Tool Design

 

[roughwood]

Suprisingly when I thought this cant possibly work I was somewhat wrong. In Through Curves I selected the right duct, then the merged area, then the left duct, and it went through without failing. It didnt get me the shape or ability to edit I wanted but still it executed without sharp curvatures or swooping around completely in the wrong direction, besides the sharp edge down the symetry line which I would expect. Unfortunate we cant post images. If the problem persists I may FTP images to help people picture what is going on.

Keith Young
keith.a.young@comcast.net
Walway Enterprises
UG Tool Design

 

[Xwheelguy]

Through Curves & Swept are pretty similar in how they behave, with the exception of guide strings & continuity assignment. Should you desire one section to continue further along the resulting surface, just add another set of strings close to the area where you want it. You might be able to use Swept to get this cross section then extract edge curves to obtain the middle set of curve strings. Delete the Swept feature & edit the Through Curves to add the new curve strings.

Hope that isn't too confusing.

I've found that when freeform modeling, it's not uncommon to have to use 2 or 3 commands just to come up with the necessary defining curves to create the end surface.

The bbsnotes page that I mentioned earlier allows you to attach images or even UG parts. You can also use Outlook Express as a newsgroup reader so that it's like emailing people. Don't get me wrong, this forum is great & full of helpful information, but sometimes images are necessary to clearly get a point across or to enhance an explanation.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[roughwood]

All this time I thought I was the only one who had to create a dummy surface to get the curves to make the real one. Its hard being an intelligent enough person to know your doing "the blind leading the blind" while not knowing a better way to do it.

I tested that command you mentioned cowski, it was a very good answer you gave me, but I was hoping to do it with closed profiles which this command does not yet support. I am sure I can find a way to trick UG into doing what I wish, eventually, lord knows we must do this alot. I suspect the fun part will be getting the "parting line" or split (made to trick UG into making my circle cross sections) to join with good continuity, but I am not that far yet. The command looks very irritable, I hope it doesnt rub off.

NK, I will look into this website you mention. I have many times but I keep getting a dead end since my boss lost his webkey information. our techy is in venezuala, NX2 doc doesnt work, frustrating. I'll just ask him to try and get me my own account. I remember trying to explain to someone how to make a 3 sided through curves mesh, and it was just impossible without some graphical image to turn my 100 greek words into 1000 greek words.

I really appreciate your guys help so far, once you use UG so long, new things you learn are few and hard to find, but incredibly usefull.

Keith Young
keith.a.young@comcast.net
Walway Enterprises
UG Tool Design

 

[Xwheelguy]

If you can find your actual license file, there is a webkey access code in the header of that file. Open the ugnx2.lic file with Notepad or a similar text editor & you can see if that will grant you access. Once you get access, you might be able to set up more than one account. If you can't get access using your individual license, use another one if you have it, as EACH license comes with its own unique webkey access code.

I believe the default install path for the license file is C:\Program Files\EDS\License Servers\UGNXFLEXlm.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com