I notice the maximum pressure recovery is .86 for these ducts.

What does that mean to us in real terms?
John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy
West Palm Beach, FL

That means if you are going 100 MPH the dynamic pressure is
26 pounds per square foot or .18 psi. So 86% of the that is
.15 psi. It is 86% of what every the dynamic pressure is.
That is why ducts are described in pressure recovery terms.

Paul Lamar

Paul,
I have been looking at those NACA ducts and it seems to me to be somewhat of
a bell shape.
Your comments ?
Would this shape be good for exit ducts also !?
George (down under)

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.

Bill

I personaly feel that the NACA ducts are highly over rated. I do not think you will
see where any
serious designer uses a NACA duct for critical high flow inlets. Cockpit air, and
possibly
engine inlet (Carb, inj, etc) are about the only place I would consider them. Engine
cooling, oil coolers and radiators deserve a real inlet. Vance

 
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