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OK George, my memory is now jogged having seen your
drawing. I liked the design when I saw it the first time but discounted it for
my application because I couldnt see a good way to make any muffler with a
tangential entry fit my airframe. This is the same reason I passed on Al's
proven muffler design.
I think the use of cooling airflow introduced into
the muffler makes a lot of sense and this is something your design has in common
with the YO-3A muffler I've been talking about. I believe the YO-3A design would
prove superior by virtue of the greatly increased volume of the muffler and the
use of absorptive materials.
Of course until someone builds one and tries it who
knows if it will hold up to the abusive exhaust output of a rotary. But the
YO-3A design does have the advantage of being flight proven in a pretty tough
environment - low altitude recon in Vietnam.
Your muffler design (or Al's) is a winner if
the goal is to keep the muffler within the confines of the cowl. My cowl is
already too tight without a muffler in it.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Thursday, October 08, 2009 9:18
PM
Subject: [FlyRotary] Re: Your
muffler
Al,
Not tested yet, but have one almost complete for
the single.
The cones are there to stop the sound
waves having a direct line of sight out the rear end, the sound waves
will be going all over the place within the exhaust and I tried to replicate
that with the zig zaggy lines.
There is no restriction as the area around the
back to back cones, is equal to the area of the 2" exhaust
manifold area.
However I do take your point on swirl
restriction, but I don't see a problem as it will swirl out the end, whereas
sound waves travel in a straight line ( I think). Bill did have me put in a reflector plate opposite the incoming
exhaust, but I don't know if this will interrupt the swirl motion, I suspect
it might. The reflector plate is on the LHS of the parts count - photo
attached.
George ( down under)
George;
Nice
design. Has anyone run one of these yet.
My concern with
the tangential muffler is something called ‘swirl flow choking’ – discovered
in connection with a similar attempt with gas turbine exhaust. High
circumferential velocity tends to keep the flow from moving out the end, and
consequent pressure buildup. I don’t know whether it applies to the
pulsed flow, but it might, and your conical restriction toward the outlet
could make it worse.
To avoid that
possibility in my tangential muffler I added internal vanes at a 45 degree
angle opposite the ports, and extended the header pipes into muffler to a
squared end. Disrupts the circumferential flow and helps direct the exhaust
toward the exit.
Your depiction of
the idealized sounds waves going axially; ah-h, well; maybe/maybe
notJ.
Al
G
-----Original
Message-----
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich
Sent: Thursday, October 08, 2009 1:14
PM
To: Rotary motors in
aircraft
Subject:
[FlyRotary] Re: Your muffler
There you go matey. All off the
shelf SS cones and tube.
----- Original
Message -----
Sent:
Thursday, October 08, 2009 9:32 PM
Subject:
[FlyRotary] Your muffler
Do you have a photo or
drawing available of your muffler design..........I seem
to
remember seeing some design info in
the past but do not know where to find it......
--
Kelly
Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from "George
Lendich" <lendich@aanet.com.au>: --------------
>
Ed,
> Cones are the GO.
>
> Any bare edge will take
a battering from the heat and shock waves. Cones
> formed back to
back eliminate any edges.
>
> There must be supporting
structure for the cones, I've used 1/4" solid
> round bar welded
into the exhaust skin.
> George (down under)
--
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