Adjustable Jam Jar

[John Werner]

Here is something that I found on the Internet which is very close to a jamjar and really purrs when you hold a 20" pipe over the 1-1/8" hole!

It's a bargin at $3.95, take a look at http://www.hotstones.com/order.htm

and look at the bottom of the page at the alcohol burner

John Werner[/code][/url]

[Don.K]

That's an alcohol burner off a fondue pot!

[John Werner]

Sure, it's a pot warmer but many thing can be used for something else like Larrys drinking mugs used for combustion chambers.

Perhaps you would like to see a demo of the setup and the noise that it makes. Ye of little faith!

John Werner

[larry cottrill]

John, with a 1.125-inch throat, that puppy must put up a pretty good roar. It's a nice design, with lateral breathing holes, like Hank showed in his article in the last issue of JetZILLA. What's the length [bottom of the whole thing to top of the cone]? Is it really just 'chrome' as the ad says, or does it seem to be stainless? [Probably, not, I guess, for four bucks.]

Man, you've just got to find a tubular stack that press-fits into that hole -- try to find something as long as maybe 2.2 x chamber height, or so. That would be a classier version of my old 'Long Tall Sally', which ran pretty well [about twice, when apparently conditions were just right].

L Cottrill
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[John Werner]

To dispel any myths about this alcholo burner AKA "Potwarmer"
here is the address where you can see my demo.

http://www.quilts-etc.com/potwarmr.wmv

Comments welcome good or bad.

John Werner

[larry cottrill]

John -

This is very impressive!

So - there IS a stack involved in getting pulsation. The reason the stack makes a difference must be what Hank alluded to in his article: increased velocity [as evidenced by the 'buzzing' sound it makes, which is from the rapid 'pops' of ejected gas]. It's extremely interesting that without the exhaust stack, you have a smooth 'burner', while gently lowering the stack in place transitions smoothly into pulsing operation.

You should try rigging the stack on a stand that will keep it in line with the hole but allow it to be gradually raised and lowered, just the last 1/4 inch or so above the top of the burner, and experiment with what kind of 'throttling' takes place in moving it [after letting it run a while to thoroughly warm the stack]. That might be useful knowledge. Another thing to watch for would be whether the flame ejection from the breathing ports seems to be affected by these shifts in stack position. It would also be fun to try a stack that's flared at one end, in both orientations and varying positions.

You should publish the dimensions. The most interesting thing about these would be the ratio of total breathing port area to exhaust area. Also, exactly what alcohol was used as fuel? Will it start up pulsing immediately if you put the stack in place and try to light it at one of the breathing ports?

The obvious difference between this and most combustion chamber & tailpipe designs is the extreme shortness of the chamber [or in jam jar terms, the distance between the fluid surface and the exit port is very small]. One thing quite noticeable that this does is promote flame ejection out through the breathing ports, though even here that might be minimized or avoided if the exhaust velocity were significantly higher.

Nice discovery, John, of a cheap and interesting little experimental tool!

L Cottrill
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[Mark]

That was an interesting flame du jour there. I was toying around with a thought of using a catalyst such as the high surface area hex ceramic car catalytic converter material found in exhaust pipes. They are made up of many little tubes of platinum, paladium, or other active element coating mixtures that convert unspent fuel into spent fuel.
If you douse my platinum coated pellets or palladium coated carbon with methanol, they quickly heat up without any need of preheating. They will glow red hot in fact. Either these or some honeycomb car catalytic converter material might be an interesting thing to try in the howler tube arrangement. I have heard that you can even melt a catalytic converter in a car if you are spewing out unburnt fuel from imperfect combustion. So if you recall, a howler tube can rattle chalk boards and frighten the dead, if it kicks in suddenly, so I was wondering if some sort of ceramic material might be able to be fed methanol either through injection below the ceramic or into the ceramic in such a way that a howler tube might transition into a full-fledged valveless pulsejet with the feedback from the air/fuel impinging off some sort of flat surface of the heat source. The device might start in the verticle and be able to sustain horizontal flow producing measurable thrust. Even copper gauze or wire will react and glow red hot with methanol, but you must first initiate the reaction by preheating. This in fact, is how formaldehyde is made, as an incomplete reaction of methanol and air over the copper catalyst.
How interesting it might be to start out with a purr and kick in to a roar.
Mark

[Bruno Ogorelec]

Mark,

An interesting idea, but I don't think the Rijke tube is likely to turn into an engine and produce thrust. Unlike a pulsejet, it only shakes the gas column. There's nothing to push a gob of hot gas in a particular direction.

In fact, the tube needs to be vertical, so that actual movement is induced by the density differential. In opulsejet terms, the hot little howler is interesting only insofar as it obeys the rules af acoustics under the circumstances of combustion.

In order for the contraption to be a mover, rather than just a shaker, Mr. Kadenacy would have to make an appearance and persuade gases to expand and contract with much greater elan than they do under the influence of sound waves.

Bruno

[Mark]

Mark,

An interesting idea, but I don't think the Rijke tube is likely to turn into an engine and produce thrust. Unlike a pulsejet, it only shakes the gas column. There's nothing to push a gob of hot gas in a particular direction.

In fact, the tube needs to be vertical, so that actual movement is induced by the density differential. In opulsejet terms, the hot little howler is interesting only insofar as it obeys the rules af acoustics under the circumstances of combustion.

In order for the contraption to be a mover, rather than just a shaker, Mr. Kadenacy would have to make an appearance and persuade gases to expand and contract with much greater elan than they do under the influence of sound waves.

Bruno

I was thinking of perhaps a plate that isn't quite the diameter of the tube so as a strong enough feedback could build and then dump in adequate fuel to sustain higher combustion rates. I use to have a little tiny valved pulsejet that would bumble bee for several seconds on just a prime and then kick in by it self as well and whine sharply, hurting my ears. Then too just imagine a Lockwood stretched out straight in the verticle. Most likely it would work as a howler tube if fed a small amount of gas and also remember Gary has done the "mathmatically impossible" by starting his Lockwood without forced air. And if I had a fuel feed for my tiny Logan, I could start and run it without the need of forced air too, I feel.
So I don't think this effect would be seen as anything more than a slow starting valveless that got the love it needed using the chimney effect to get things going into a Dresden firestorm. Getting a column of air to eat more and more might be seen as nothing more than a cheap parlor trick. Then you could rotate the thing horizontally. It just seems to me such a device could be conjoured.
Mark

[larry cottrill]

Mark -

I also think you could do something like this, not with a true howler tube, but with a simple 'jam jar' type device like John's, but with one addition: a Logan-style tube with external fuel supply and 'choke plate' at the outside end.

Imagine John's device [but with the stack solidly attached] starting out in the vertical orientation, with the additional breather tube choked off. It would be virtually identical to what he has now, and can undoubtedly be started by ignition at one of the little holes. Let it warm up a couple of seconds, and ease open the choke plate, allowing more air AND carbureted fuel into the chamber. The trick would be to set up the fuel flow so the added combustion energy is just balanced by the added air - some experimentation required. By the time the alcohol pool is gone, you have a running carbureted engine that can be reoriented to the horizontal. You might argue that at the same time you're phasing in the Logan tube you need to be closing off the six holes, and I'd believe you. Sounds tricky, but why wouldn't that work?

I think the geometry of the 'jam jar with vertical stack' is basically right, EXCEPT that the intake air has to be tightly restricted because of the very tiny amount of vapor picked up in each cycle. There is no reason the exact same device couldn't convert to a thrust engine IF more air can be provided to properly combust the increased fuel.

L Cottrill
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[Mark]

Mark -

I also think you could do something like this, not with a true howler tube, but with a simple 'jam jar' type device like John's, but with one addition: a Logan-style tube with external fuel supply and 'choke plate' at the outside end.

Imagine John's device [but with the stack solidly attached] starting out in the vertical orientation, with the additional breather tube choked off. It would be virtually identical to what he has now, and can undoubtedly be started by ignition at one of the little holes. Let it warm up a couple of seconds, and ease open the choke plate, allowing more air AND carbureted fuel into the chamber. The trick would be to set up the fuel flow so the added combustion energy is just balanced by the added air - some experimentation required. By the time the alcohol pool is gone, you have a running carbureted engine that can be reoriented to the horizontal. You might argue that at the same time you're phasing in the Logan tube you need to be closing off the six holes, and I'd believe you. Sounds tricky, but why wouldn't that work?

I think the geometry of the 'jam jar with vertical stack' is basically right, EXCEPT that the intake air has to be tightly restricted because of the very tiny amount of vapor picked up in each cycle. There is no reason the exact same device couldn't convert to a thrust engine IF more air can be provided to properly combust the increased fuel.

L Cottrill
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For some reason that brings to mind Reynst and his variable geometry starting where the bottom of the chamber is moved up and down to "walk up" so to speak, the combustion energy. Whatever happens if such a device is built, it will blurr even more the defining nature of jam jar modes and pulsejet modes.
Mark