Minuteman From United States of America, joined Aug 2000, 271 posts, RR: 0 Reply 2, posted (12 years 1 month 3 weeks 5 days 6 hours ago) and read 857 times:
It's really that incomprehensible.
What are you talking about? To which certain airfoils are you referring?
In general, bound vorticies are going to be perpendicular to the lifting-line of an airfoil. This dives into 3D Potential flow. It involves lots of ugly math that ends up being only an approximation anyway.
TAA_Airbus From Australia, joined Nov 1999, 726 posts, RR: 0 Reply 4, posted (12 years 1 month 3 weeks 3 days 1 hour ago) and read 818 times:
basically any aerofoil will produce vortices.
The main way a common vortex is produced is higher pressure air underneith the aerofoil pushing it self out from under the wingtip and then tries to roll up to the low pressure on top of the aerofoil. This is what initiates the spiralling vortex.
The idea of the winglet is to try stop the air forcing its way up and therefore disturbing the spiralling air which is being formed.
Other ways in which vortices are minimized are tip tanks, on light aircraft (eg. Cessna 310) or a blended wing, also on some light aircraft.
I hope thats what you were asking, like minuteman said, the question wasnt very well asked!