Re: NACA ducts - how do they work?

"Nigel Marston" wrote:
> Anyone know how a NACA duct works and what it is supposed to do? I've
> seen them used to expel air from a bonnet and as a scoop to catch air
> for induction. They've been used in both orientations, i.e. narrow end
> backwards AND forwards. I've also seen the narrow end opened OR the wide
> end open. I'm sure I read somewhere that they utilise a venturi type
> effect.

They were designed as shockingly effective ways to suck air in from an
attached flow without causing measurable amounts of drag.  In the intended
installation the pointy bit goes forward and they suck the air in.  They
can be used inside out/upside down but they're no longer the optimal
design.

The exact proportions of them and the shape of the leading edge of the top
surface are critical in getting them to work to their best, having said
that unless you're trying to get the last few percent of flow out of them
they'll work plenty well enough.
-------------------------------------------------
To manage your subscription options visit :-
http://mailman.se7ens.net/mailman/listinfo/sevens