View Single Post
Old Oct 11, 2012, 06:37 AM
JetPlaneFlyer is online now
Find More Posts by JetPlaneFlyer
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Joined Mar 2006
13,419 Posts

I think the debate is largely one of semantics.
In aerodynamics I don’t know of any recognised phenomena that is known as 'a trailing edge vortex' (other than the starting vortex) and that's what I said. To repeat: The trailing edge (at least on normal airfoils with sharp TE's) does not MAKE a vortex.. Vortices that may be made somewhere ahead of the TE simply go past the TE as they get carried along with the air. In separated flow these arent stable vortices like we get ot wing tips, they are unstable random tumbling of the airflow which (if you check my post) I refered to as 'chaotic turbulence'.. This random tumbling isnt what most people would consider a vortex, though if you want to be strictly accurate, yes this 'chaos' has vortices within it.

Anyway I guess the next question is 'does a bottom step actually shed vortices' and 'if it does do these have any effect on the flow separation on top of the wing?'
If I had to guess I'd say 'probably' to the first point and 'highly unlikely' to the second. I can’t see any logical explanation as to why vortices shed from the lower surface would prevent stall on the upper surface?

And don’t forget that the claim made for the KFm design is that the vortex doesn’t shed but sits firmly trapped behind the step. So the whole idea of vortex shedding is contrary to the usual claimed principal of operation of the KF airfoil.

JetPlaneFlyer is online now Find More Posts by JetPlaneFlyer
Last edited by JetPlaneFlyer; Oct 11, 2012 at 07:30 AM.
Reply With Quote