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Right on the money, Kevin. I did not make it
clear in my first message that I calculated the 1/4 wave length of several
harmonics of rpms from 1500 - 6000.
Then I chose the lengths that occurred most frequently in that matrix for my
chamber lengths (distance between discs).
This gave me six intervals for the discs spacing ranging from
2.5" to 11.2". If I had a longer tube I would have picked a couple of
longer intervals as well.
According to the theory (If I understand it
correctly) what is happening to deaden the sound is that the exhaust pulse
encounters a disc (what appears to it as a solid disc) and is reflected
backwards. When it encounters other incoming waves it interacts destructively
thereby attenuating both waves. If energy survives to reach the up-stream
end of the chamber it hits that disc and reverses direction again, etc.
This would occur in each of the chambers between discs repeatedly many
times a second. So you have this chaotic mixing of the waves in
the chambers attenuating the sound wave but not seriously interfering with the
exhaust gas movement out the tube (hopefully).
The sound waves are reflected from
each side of each disc and a bit from the open end as well - however,
if the discs have done their job the exhaust sound pulses are considerably
attenuated by the time they reach the end of the tube.
Ed
----- Original Message -----
Sent: Wednesday, December 01, 2004 12:43
PM
Subject: [FlyRotary] Re: Reactive vs
Absorbtion Mufflers for the Rotary engine
Ed -- would it make sense in the
placement of the reflecting inserts, to space them in an increasing series, so
that they react to various frequencies, rather than trying it hit one
frequency? are the reflected sound waves created only from the open end,
or from any surface?
----- Original Message -----
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