jordan zeairs asked 1 month ago
I am currently working on analyzing a wing sail design for a school project and need some assistance with the best analysis setup.
The design consists of:
- Main sail: NACA 0018 airfoil with a chord length of 4m
- Second wing sail: NACA 009 airfoil with a chord length of 1m, starting at 4.04m
- The two sails have a small gap of 0.04m between them.
Could anyone provide guidance on:
- What is the best method for simulating this setup?
- How should I approach wake settings to account for the gap between the sails?
Any help, advice, or suggestions would be greatly appreciated. Thank you!
jordan zeairs answered 1 month ago
I used the VPW and the wake panels don’t seem to be touching but the flow streams coming off of the main wing are going through my secondary wing. In the example I noticed the reference cord is the main sail that is aft of the jib. Should the reference cord be the main sail or just the most aft sail?
Thank you,
Jordan
The reference chord is an arbitrary value used to normalized the coefficients CL, CD etc. It has no effect on the calculations of the VPW or of the streamlines.
If the vortons seem to go through the trailing wing, it’s usually due to the setup of the boat geometry w.r.t to the wind direction.
The case where the two wings are close to each other or where one is closely trailing the other is difficult to handle for a panel method due to numerical interations between the panels of both wings. If you can send me the project file, I’ll have a look and try to make some recommendations.
André
I also wanted to mention that the second sail is intended to add camber to the system. My plan is to conduct multiple analyses at different wind speeds and angles of attack, with the main sail stationary and the second sail rotating from 0 to 45 degrees.
The Fujin example linked in the validation section of the online doc. may provide some guidance.
Regarding the wake, the main thing is to verify that the wake panels do not intersect each other or intersect the sail panels. The VPW is also an option to avoid these problems.
André