[Gasification] thermoacoutics, rijke tubes, sondhauss tubes, pulse jets-- how do we make them not work?

[Mark Ludlow]

The trick is to modulate the resonant frequency. (Bends won't work much
differently here than they do on a Tuba!) The standing wave formed has to be
disrupted.  Unless a lower frequency pulsing is heard, this is not analogous
to a pulse jet which has distinct regions of rarified and compressed gasses.
Mark

 

From: gasification-bounces at lists.bioenergylists.org
[mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of WJ Seidl
Sent: Wednesday, February 16, 2011 4:34 AM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] thermoacoutics, rijke tubes, sondhauss tubes,
pulse jets-- how do we make them not work?

 

Jim:
Drill a hole.  That's right, a hole.  About 1/4 inch should do.
Put it a few inches up on that pipe extension (from the joint you added that
section to)
If that doesn't solve it, put a bolt or rod in that hole, across the gas
path.  That should do it.  
If you don't care for a hole, try adding a bend at the top of the tube, say
45 degrees full diameter.

The trick is to modify the modulation frequency of the gasses passing out of
the pipe.
But you already know that.

Best,
Wayne 

On 2/16/2011 2:11 AM, jim mason wrote: 

any ideas out there for how to make a pulse jet robustly not work?
 
we're having lots of problems with thermoacoustics now that we've put
a tall stack on our gasifier swirl burner.  we're using a tall stack
now to keep startup gasses away from the operator.   the swirl burner
is 5" in diameter, 10" tall.  we've added a 4 foot or so stack of the
same 5" diameter.   it looks like this
http://www.gekgasifier.com/forums/showthread.php?t=501  (though this
one without the joint at 10")
 
when run under high load, it howls rather loudly.  if art, it would be
fabulous.  if a genset, not so good.
 
 
any other ideas or experience for how to make your pulse jet not work
under any circumstance?
 
jim
 
  

 

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