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Re: REFLECTOR: duct installation

Counter flow (as I understand it):
The counter flow concept has the coolest air flowing over the
heat exchange system end with the lowest coolent temperature.
These systems have some type of linear flow design.  Hot water
and cold air would come from opposite ends of the heat
exchanger.  In the perfect design the delta T is constant.
This is because as the air moving by the coolest water picks up
heat, it (the air) is moving over warmer water.  When properly
designed the difference in the air to water temperature is
constant and ideal for the speed of the air movement.  This
make the heat transfer rate ideal for the two media.  Anyway
that's the therory as I understand it.  Can it be designed our
use?  I don't know the engineering well enough to answer that
question.  It just sounds like an interesting possibility.

I also heard a suggestion form an aero engineer that we pusher
planes should develop a spinner with an internal vane that
could pull air to the other side of the prop.  He suggested
that one might even feed the exhaust out this way.  His basis
was that this would provide less turbulence to the prop disk,
increase power and improve cooling efficiency.

Too many options
Jerry Brainard


From: reflector@awpi.com AT SMTP on 01/11/99 05:46 PM

To:   Jerry Brainard, reflector@awpi.com AT SMTP@ANTHEMCC
Subject:  Re: REFLECTOR: duct installation

Jerry Brainard wrote:

> In considering a water cooled engine solution for the XL, I
> have been thinking about the cooling problem.  I have seen
> examples of counter-flow cooling that are very efficient.

Counter-flow?   Sounds like something interesting to learn

Don't we need electric fans to cool on the ground?

Doesn't the coolant pressure effect the heat exchange?

Don't thick cores work very well at high velocities?

In theory at 200 mph we should get lots of cooling right?  In
practice most
cooling (water or air) installations I have seen
don't work properly at high speeds because the air piles up way
 out in front of
the intake scoop and goes around it.  In
pushers this turbulence is also a prop efficiency problem.
I only know this from what I have seen funnels do in high speed
wind tunnels.
They work best with the small end into the
wind.   Maybe some yarn on the plane near our intake scoops
could tell us something from another airplane close underneath.

What good is the "correct" size radiator if not much air is
going through it?