Today's Tangent

[Mark]

Toying with my 4 inch diameter threaded steel jar that is 5 inches tall, I tried putting a snorkel down into the jar at various depths instead of the typical flush with the lid approach. You get more confinement and a loud Ka-bang because of the more torturous path the combustion must follow to get out.
My snorkel however is a piece of chromed copper segment similar in shape/origin to this very same object pictured. That is, my snorkel looks kind of like a pulsejet with a shortened tail.
http://en.wikipedia.org/wiki/Image:Plum ... inting.jpg
Just imagine sawing the pictured chromed shape near the bottom and unscrewing the top, that's the piece I am working with. I found it in a large box of copper at the scrapyard. The belled part is the end that is housed inside my steel jar and a short section of the narrow end extends a certain length above the lid, depending on how deep I slide the piece into the jar.
So at some depth, I get a bang followed by a gas spring effect where you can make out a vague but strong reving/snorkeling in the instant following the bang, like it wants to go/run but not quite. My hope is to find a way to get more compression and still sustain feedback in this disproportionately shaped "canosity."
Maybe by some tangent I can help my restrictive inflow problem by developing a greater negative pressure on the blast phase. The distance the gases have to traverse in and out is short really.
I'm misting with methanol and just lighting the exhaust end, not sparking the chamber, there is a small amount of methanol on the bottom of the jar, just like a jam jar would have.
Mark

[Mark]

I broke down and took a few pictures for your interest. ha
I'm breaking new ground using urinal parts I think.
Mark

[Mark]

One thing that is funny about the chromed copper pipe segment is that when I tried to buff the chrome off the copper with my spinning wire wheel side of my grinder, it really adheres to the copper and I barely got any to come off as hard as I tried to shine it up. Chrome must be fairly hard stuff.
Mark

[Mark]

Funny, even my insignificant little pipe segment from a urinal, ( http://www.plumbingsupply.com/chicagourinalvalves.html )can hang out with interesting company. Check out some of these artistic designs I came across.
Mark
http://gargles.net/wp-content/uploads/2 ... d090_o.jpg
http://www.urinal.net/naturescall/pitcher.html
http://www.urinal.net/naturescall/
http://www.urinal.net/topfive.html#
http://www.worth1000.com/entries/108000 ... PUWT_w.jpg

[Mark]

After reading the latest PDE post, the one with the coaxial flow design, it dawned on me, (the tangent), it might be kind of fun to design a coaxial flow jam jar of some sort. The first thing I thought of was what if I put a small jam jar inside a larger jam jar. How would I tell if it was even running? Maybe by adding a flame colorant to the small jar's fuel, this would help indicate that it was running and not merely engulfed by the larger vessel's methanol fire. Or you could provide less fuel to the larger jar and have it die out whilst the smaller still sustains. Well anyway, there must be some way to prove they both are or were running together in harmony.
I don't know what good it would be other than an interesting/motivating thought to see a jam jar within a jam jar. The smaller jar might need a little snorkelette to get/reach enough of the fresh air on the inflow phase to sustain itself, but still fully contained in the larger jar. And of course it wouldn't hurt to have the smaller jar made of quartz ala 1600 C melting point, low coefficient of expansion, etc. The smaller jam jar is going to be getting hot city being partially jacketed/enveloped by a dancing cone of fire and having internal combustion going on as well, if the nature of the design allows.
Mark

[Mark]

It might be fun to try a coaxial flow pulsejet too. Maybe by some means it would pep up a pulsejet the same way it peps up a PDE.
Mark