Re: 737-400 Vortex generators

Date:         03 Oct 99 17:38:26 
From:         burkhard.domke@pace.de (Burkhard Domke)
Organization: WiNShuttle, DFN - Deutsches Forschungsnetz eV
References:   1 2
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On 16 Sep 99 16:42:50 , Ernie Fidgeon <efidgeon@videon.wave.ca> wrote:
>My understanding is that the generator causes the local flow to rotate
>downwards onto the wing in the areas where separation starts from the
>airfoil.  This downward flow delays or prevents separation and improves lift
>performance.  Not sure what the drag impact is.  I have a colleague who just
>finished engineering and did some vortex generator experiments with an
>airfoil intended for the SAE heavy lift competition.  Even at his Reynolds
>numbers he found a significant lift improvement.

Vortex generators are used to re-energize sluggish boundary layer flow
by trailing vortices as a means to prevent separation. Lift
performance is improved for a given AoA only if there would have been
separated areas without VGs to begin with. Likewise, VGs impose a
small drag when used in non-separated areas, but in turn prevent
considerable drag rise and lift losses associated with flow
separations. Commonly, VGs are installed as an afterthought to fix
unforeseen separation and buffeting problems.

A vortex generator may also serve as an aerodynamic wing fence
(Vortilon).

regards,
Burkhard