Al Gietzen wrote:

What am I missing here?  It seems quite apparent that the exhaust

will

come out both ends.  The pressure at the 'back' end of the inner

tube

will be quite high.

Al

It depends on the area ratio of the concentric space to that of the

tail

pipe area. It should work like a thrust augmentor. There may be a

slight

design change required to get a venturi shape around the cooling pipe
exit.

Dynamic pressure could also be fed in at the front to enhance the

flow.

Paul Lamar

A similar item is used in industries that use a lot of steam.  It's
sometimes called a thermo-compressor but can also be used to draw a
significant vacuum.  High pressure steam is used as the motive force

to

recycle low energy steam back into the system.  In our case the engine
exhaust is the motive force and the cooling air around the muffler is

drawn

into the system.  As a steam powered eductor they can pull a vacuum

down to

28 inches of mercury (we don't have THAT much energy

Take another look at that eductor.  I'm guessing you will find that the
high energy steam jet is on the inside and the low pressure outside;
just like the case of the augmentor.  That is the critical difference.

Al

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