Neil, John,
No they don't work well in reverse (even though you see them used that way).
The dropping floor of the NACA duct creates a low pressure area and the
S-curved sides create a vortex which pulls air down into the throat of the
duct without extending up out of the original surface.
A rear facing scoop should be of equal area or even expanding area for best
effect.
Dale C.
Subject: RE: Spoilers vs. vents
John;
If I remember correctly, NACA ducts depend on laminar flow
to work
efficiently and by the time airflow over a sports or comp
coupe gets to the
rear it's pretty turbulent.
I don't know if NACA ducts are reciprocal-- that is, if they
work "in
reverse."
Regards, Neil Tucson, AZ
!
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