I don't think so. The whole idea of a NACA duct was to deal with a
boundry layer and you don't have a boundry layer when the
air exits the rad.

Paul Lamar

The curve in the NACA duct helps induce a pair of inward rotating
fixed vortices.  These pull themselves down into the inlet and cause
the inlet to work.  I can't see how this would happen in reverse.

George Lendich wrote:

Bill/ Paul
Thanks Bill that does explain it much better.
I've seen many exit ducts similar but flat bottomed,
they presumably create a lower pressure area and help suck out the air.
George (down under)

 
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