|
[Sponsors] |
June 27, 2012, 15:45 |
Lift Coefficient Problems
|
#1 |
New Member
Hannah Mac
Join Date: Jun 2012
Posts: 15
Rep Power: 13 |
I'm running Fluent on a simple UAV design and I'm trying to get a lift coefficient curve. I have a set of design points that run from an angle of attack of 0 to 25 degrees. I get a max lift coefficient around 16 degrees. It goes down at 18 degrees. Then goes back up when it gets to 20 degrees! What is going on?
I've tried both steady state and transient with no real difference. |
|
June 30, 2012, 03:36 |
|
#2 |
Senior Member
Join Date: Mar 2011
Location: Germany
Posts: 552
Rep Power: 20 |
Running steady state solver is out of question at such a high angle of attack because there is lot of flow separation at these angle of attacks but the problem you are telling looks quite strange. Give it a try by changing your time step and then let me know what happens.
Regards |
|
July 3, 2012, 12:02 |
|
#3 |
New Member
Hannah Mac
Join Date: Jun 2012
Posts: 15
Rep Power: 13 |
It turned out to be as simple as a mesh problem in that the mesh wasn't fine enough around the UAV. The wind tunnel was so large that even when the cells looked small, it wasn't enough. I have fixed it now, and I'm getting a beautiful coefficient curve even with steady state. (I'm not going too far past the stall angle) Thank you!
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
turbulence models and lift coefficient for naca 0021 | Nick R | CFX | 7 | November 29, 2022 16:51 |
Lift coefficient in Eulerian multiphase model | hennas | FLUENT | 1 | July 4, 2011 16:50 |
Coefficient DRAG and LIFT - Cylinder 3D | Jwolf | CFX | 11 | February 4, 2010 05:08 |
drag and lift coefficient | Noé | Siemens | 5 | July 13, 2004 10:21 |
Help needed - lift coefficient on front/rear axle | Jan Jagrik | FLUENT | 0 | September 21, 2000 10:21 |