Bill Jepson wrote:

Paul, The attached jpeg is a variation on the tangental muffler

theme.

The intent is to cool the exhaust system using the exhaust energy. A
outside air source is provided near the front. The design could also

be

inverted, (exhaust inside the the can), if the inside tube wouldn't
provide enough cooling. The tail pipe mixing should also make it

a bit

quieter.  comments? Bill Jepson

That is a really great idea Bill. I really like it. I think it is
THE soluttion.

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).  As Paul and Bill
said, if it is designed right it will draw the air from the engine room
into the exhaust system.  You won't need any dynamic pressure feed from the
front of the cowling.  It will do a fine job of creating an induced draft
in the cowling which will help to keep other critical systems cooler.  The
pipe downstream of the mixing chamber will need attention to detail in
order for it to work right.  That part of it may not fit in the cowl and
will be a challenge for the pushers.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode

You got any dimension suggestions of what might work Mike?

Paul Lamar

Joseph Berki wrote:

Hi Paul,
         The use of this design as an exhaust augmenter is very similar to
Charlie Airesman's Vari EZ.  If the header could feed the outer can and the
can will act as a muffler then discharge the exhaust into the center tube
using a venturi tube or tubes placed at an angle pointing aft.  A whistle
slot could be placed at the base of the venturi tube where it enters the
center tube.  The diffuser from the rad could feed the center tube and in
the case of a pusher the lower cowl could duct air around the outer skin to
provide appropriate air flow and cooling to the VAM(P) for pusher
application.  I have been thinking about this for a while but the AC
construction is a priority.

Joe Berki

 
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