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Old Dec 08, 2014, 11:20 AM
Sink stinks
Montag DP's Avatar
United States, GA, Atlanta
Joined Apr 2005
4,554 Posts
Originally Posted by martig View Post
As far as I've understood camber and thickness are reduced to have better performance at low Reynolds. I think flow separation is the issue.

I used 4 operating points - 0, 0.3, 0.6, 0.8 and just scaled the root's Reynolds to match.
What happens when you run the final sections at different Reynolds numbers? For example, take the root section and run it at the Cls you optimized for, but with the tip Reynolds number. Does it perform better than the optimized section for the tip? If so, then it means the optimizer is having trouble optimizing the tip section. If not, then it's doing its job. You can also try the reverse, testing the tip airfoil at the root Reynolds number.

It does seem strange at first that the camber would increase going out towards the tip, but maybe it actually makes sense. If the lower Reynolds number causes a decrease in Cl, all else being equal, then to get the same Cl, either the angle of attack needs to be increased or the camber. It seems reasonable that the shape could be tailored by the optimizer to increase camber while still minimizing flow separation.
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Last edited by Montag DP; Dec 08, 2014 at 11:27 AM.
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