CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Lower than expected Coefficient of Lift against angle of attack

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 10, 2023, 05:27
Default Lower than expected Coefficient of Lift against angle of attack
  #1
New Member
 
Gideon Chia
Join Date: Dec 2023
Posts: 2
Rep Power: 0
giddo244 is on a distinguished road
Hi all, for a school project I'm looking at the lift against angle of attack for a 3D NACA 2414 wing at about a Reynold's number of 200,000. However, I am getting results that are about 30% lower than expected compared to an experiment and 2 other CFD studies I found which more or less agree with each other. My apologies for a wall of text but I would greatly appreciate it anyone's help to identify places that may be causing this error. I have attached an imgur link for my screenshots and images: https://imgur.com/a/TL8pADi

1. Mesh
Firstly, my wing has a chord of 140mm and a span of 240mm. I am using a C-domain 40 times the chord. For inflation layers, I've set first layer height to be 0.02786mm, 15 maximum layers to get an eventual y+ = 1 (I have been using k-w SST). My edge and face sizing around the wing is 1.4mm and I have a body of influence with 5mm element size.
2. Fluent
Pressure-based, steady. I have been using the k-w SST model. However, trying different models (k-e realiable and SA) did not really improve my results. I have opted to use a constant value for air density and viscosity. For my boundary conditions, I will use my 10 degree angle of attack case. My reference values are taken from the inlet. For methods, I used second order upwind. For report definitions I used the vector compotents. And lastly, I intialise from the inlet.
3. Results
I get the following results. They are lower than expected vs experimental data at the same Reynold's number and lower than other CFD studies I found.

I really would appreciate any input!
giddo244 is offline   Reply With Quote

Old   December 10, 2023, 11:46
Default
  #2
Senior Member
 
Lorenzo Galieti
Join Date: Mar 2018
Posts: 375
Rep Power: 12
LoGaL is on a distinguished road
Interestingly, you are catching the correct Cl and Cd at 0 AoA. You sure you are not messing up your trigonometry calculations for Vx and Vy?
LoGaL is offline   Reply With Quote

Old   December 10, 2023, 11:54
Default
  #3
New Member
 
Gideon Chia
Join Date: Dec 2023
Posts: 2
Rep Power: 0
giddo244 is on a distinguished road
Oh my I hope its as simple as that, but I don't think this was the mistake I made.
Here are the trig numbers I used: https://imgur.com/0ZpRLom
giddo244 is offline   Reply With Quote

Reply

Tags
coefficient of lift, experimental data


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How can i get the resonable drag and lift coefficient in fluent? blivurmind FLUENT 0 September 1, 2020 23:27
POSDAT problem piotka STAR-CD 4 June 12, 2009 09:43
Automotive test case vinz OpenFOAM Running, Solving & CFD 98 October 27, 2008 09:43
angle of attack kiran FLUENT 0 September 10, 2004 09:18
Lift Coefficient Vs. Angle of Attack cfd_pro Main CFD Forum 1 August 23, 2002 18:21


All times are GMT -4. The time now is 18:34.