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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'>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<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> gasification-bounces@lists.bioenergylists.org [mailto:gasification-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>WJ Seidl<br><b>Sent:</b> Wednesday, February 16, 2011 4:34 AM<br><b>To:</b> Discussion of biomass pyrolysis and gasification<br><b>Subject:</b> Re: [Gasification] thermoacoutics, rijke tubes, sondhauss tubes, pulse jets-- how do we make them not work?<o:p></o:p></span></p></div></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><p class=MsoNormal style='margin-left:.5in'>Jim:<br>Drill a hole. That's right, a hole. About 1/4 inch should do.<br>Put it a few inches up on that pipe extension (from the joint you added that section to)<br>If that doesn't solve it, put a bolt or rod in that hole, across the gas path. That should do it. <br>If you don't care for a hole, try adding a bend at the top of the tube, say 45 degrees full diameter.<br><br>The trick is to modify the modulation frequency of the gasses passing out of the pipe.<br>But you already know that.<br><br>Best,<br>Wayne <br><br>On 2/16/2011 2:11 AM, jim mason wrote: <o:p></o:p></p><pre style='margin-left:.5in'>any ideas out there for how to make a pulse jet robustly not work?<o:p></o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'>we're having lots of problems with thermoacoustics now that we've put<o:p></o:p></pre><pre style='margin-left:.5in'>a tall stack on our gasifier swirl burner. we're using a tall stack<o:p></o:p></pre><pre style='margin-left:.5in'>now to keep startup gasses away from the operator. the swirl burner<o:p></o:p></pre><pre style='margin-left:.5in'>is 5" in diameter, 10" tall. we've added a 4 foot or so stack of the<o:p></o:p></pre><pre style='margin-left:.5in'>same 5" diameter. it looks like this<o:p></o:p></pre><pre style='margin-left:.5in'><a href="http://www.gekgasifier.com/forums/showthread.php?t=501">http://www.gekgasifier.com/forums/showthread.php?t=501</a> (though this<o:p></o:p></pre><pre style='margin-left:.5in'>one without the joint at 10")<o:p></o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'>when run under high load, it howls rather loudly. if art, it would be<o:p></o:p></pre><pre style='margin-left:.5in'>fabulous. if a genset, not so good.<o:p></o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'>any other ideas or experience for how to make your pulse jet not work<o:p></o:p></pre><pre style='margin-left:.5in'>under any circumstance?<o:p></o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'>jim<o:p></o:p></pre><pre style='margin-left:.5in'><o:p> </o:p></pre><pre style='margin-left:.5in'> <o:p></o:p></pre><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div></body></html>