Odds and ends

[Mark]

steam (LTD) thermoacoustic engine
http://www.youtube.com/watch?v=S1VEablsSQA
"My microphone does not broadcast this sound good
I do not know why...."
http://members.jcom.home.ne.jp/kobysh/e ... nkama.html
http://members.jcom.home.ne.jp/kobysh/e ... /kama.html

"If you are interested in an ancient (1802) account of research regarding acoustics and combustion, then read "Memoir on tubes rendered harmonious by hydrogen gas" by G. Delarive."
http://www-chaos.engr.utk.edu/hst/delar ... 14-iv.html

As an aside I was thinking it might be fun to fill a long pipe with steam and then collapse the vapor quickly by water quenching. The pipe would be sealed at one end and having a burst diaphram at the other for the sudden inflow of air. This akin to the collapsing 55 gallon drum effect. I wonder how loud it would be?

[Mark]

Be the first on your block to start/light your pulsejet with a pneumatic air compression lighter.
"Pyrogène: Made by an unknown manufacturer (marked CBG) in France ca. 1850. A practical pneumatic air compression lighter (piston) using tinder, comprising a small container for the latter. Fully marked lighter, showing a burning torch symbol, CBG, Pyrogène and a marking of a French patent. Extraordinary!"
http://www.vintagelighterbook.com/html/ ... hters.html

[Mark]

"The last thing you would expect is that a burning droplet of alcohol would produce enough water to put itself out. Or that a fireball the size of a pinhead would linger for eight minutes."
"One of the early surprises is the way that alcohol burns," Williams said. Alcohol is a family of chemicals, the two most common being ethanol - more familiar as grain alcohol - and methanol - the deadly wood alcohol.
"These two alcohols burn completely different," Williams said. The ethanol drops burned to extinction, or until no fuel was left. But the methanol droplets extinguished themselves, which has implications for anyone designing engines that burn alcohol. Alcohol is strongly hygroscopic, meaning it absorbs water ("pure" alcohol is impossible to produce)."
"Both alcohols produce water vapor as a byproduct, but it appears that methanol reabsorbed more of the vapor from its own exhaust. Then, when the water was heated it boiled away from the drop, taking enough heat energy with it to cool the flame and stop combustion. In an engine, that means you have to burn more fuel to do the same work."
"Williams said that the results could not be fully duplicated on the ground simply by tinkering with all possible running conditions on an engine. With data from FSDC, scientists will be able to tell better how to fine tune alcohol engine design."

"And there's the paradox. Common sense tells us that the flame should leap across the chamber, burning everything in an instant. Instead, it produces the tiny glowing dots - 1 to 10 mm (1/25 to 1/4 inch) across) that float for up to 500 seconds before they are extinguished by fans in the chamber."
Micro-fireballs Lighting the Way to Better Engine Designs
http://science.nasa.gov/science-news/sc ... 12jul97_1/

[Mark]

Kind of a lackluster configuration. I tried a much longer snorkel, a little bit longer than the tank is high but it didn't seem like it could breathe fast enough with a long exhaust/intake. It's kind of tricky figuring out a proper scale using my amateur TLAR methodology. I also tried a midsize inbetween those lengths and that failed to sustain too. Maybe large jam jars require better fueling techniques or different length-to-width ratios and possibly unsuspected intake/exhaust diameters. Needs some fine tuning to be sure.
Snorkeler Snorkeling Slowly
http://www.youtube.com/watch?v=E4Z9fwIMIcw

[Mark]

I was just burning up some old methanol and happened to hear an odd electric buzzing sound when this snorkeler was running. Too bad the camera mic didn't pick it up or if there was some way to isolate the frequency from the rest. It was a definite Zzzzzzzzzz sound that was completely steady. I turned my sound up on this video but I still couldn't detect that curious St. Elmo's Fire characteristic quality. One day I want to try creating static from the exhaust of a snorkeler. Maybe by insulating the tank from ground and then putting an agumenter above the exhaust a potential could form between the two. The other day when I was running the beer keg snorkeler, I held an augmenter pipe about 18 inches long above the short snorkel connected to the tank and it ramped up quite suddenly. It was kind of a surprise. Still it is quite fussy. I don't know how much the conical shaped top and concave bottom of the keg are affecting the performance, but I might have preferred a flat top on the keg instead of a more gradual transition. If I had a clear tank I could study the splash effect on the pool of methanol in the bottom of the tank when it first hisses and then starts and runs steadily. I wonder if a flat bottom would be better or worse or the same as a concave bottom for supporting a more robust combustion? Some false starts are quite loud and you can hear the methanol kicked up after it flames out.
I decided not to stabilize my video as offered by YouTube, instead going with the natural look. ha
"It suggests unprepared, unrehearsed filming of reality, and can provide a sense of dynamics, immersion, instability or nervousness.[3] The technique can be used to give a pseudo-documentary or cinéma vérité appearance to a film."
http://en.wikipedia.org/wiki/Shaky_camera
Jam Jar Snorkeler
http://www.youtube.com/watch?v=BopYdkQNHxA

[Mike Everman]

Fun. That snorkeler would probably run longer in a tub of water maybe.

[Mark]

The piglet snorkeler is fussy starting if I put a lot of fuel in it, but it has run glowing red hot above the fuel level for five minutes rock steady until it runs low on fuel. I haven't been able to get it to do that lately. It's not quite as lively as it has been for some reason. I think GRIM may have said it best a few years ago commenting on a piglet snorkeler video of mine. I wonder how he's doing?
"Hey Mark thanks for posting these videos , I have seen the photos and even built one a year or so back but never got it to run properly seeing these vids I am now convinced it was old fuel that was the problem , the intitial whoosh and a quick death was the best i ever achieved, having said that, the orientation of the moon wrt the ambient temperature and the moods of the combustion gods may have been a factor too "

I've tried several contrived snorkel lengths merely press fit internally or sleeved over the neck of my Slimline beer keg the last few days with very poor results. I'm starting to wonder if the vortex is breaking too soon inside the keg or if the primitive fueling is inadequate/methanol pooled at the bottom of the tank. Oddly the shortest snorkel has run the longest and today a snorkel a few inches shorter than in the previous video started slowly but sped up producing a few throaty backfire-like sounds while maintaining combustion. And the flickering/intermittent blue fire bursts were entertaining. This being the largest snorkeler I have toyed with, at least provided some sustenance to my morale today. Maybe an internal "augmenter" like Reynst had would change the flame whorl dynamics in a positve way but I have no way of getting inside the keg unless I use the ship-in-a-bottle approach/not likely. I cut an even shorter snorkel today and I will give it a go tomorrow. Maybe I could put an internal pipe of the same diameter attached to the snorkel by a few thin strips or rods to create a gap of several inches. That might direct the swirl better, who knows. Wouldn't it have been nice to have Reynst for a neighbor or friend to ask him some questions? I'm just feeling around in the dark without a mentor.

Mike, I have a small drum I can fill with water and try putting my piglet snorkeler in that to see what it does. Film at 11. ha
http://en.wikipedia.org/wiki/Film_at_11

[Mike Everman]

Ha ha who here has not bowed down to the combustion Gods? Of course after you mention ship in a bottle vortex ring, all I can think about is just that. Ha

[Mark]

I tried my newly made shortest snorkel and that didn't work. Then I tried sleeving a 6 inch piece of plumbing pipe nipple inside the 4 inch tall snorkel and that worked well enough. The outer thin 2 inch diameter exhaust pipe holds the sleeved pipe snuggly enough to stay put. A few days ago I launched my good 2.5 inch diameter titanium pipe in the air and it landed back on the tank denting the thin-walled 30 inch pipe in two places. How sad, it was a pretty piece of titanium.
Anyway, I got out a short drum/barrel and put water in it for a cooling tank but became frustrated by the buoyancy problem. Rather than hassle with that I figured it would be better to get something that revs up nicely if only for a short burst before moving on to longevity or water cooled engines. However, having water at hand when the 6 inch snorkel/beer keg putted along nicely, I sprayed it with the hose from a distance of about 10 feet, to avoid the fumes and slight noise. What a mistake in some sense. I was stuck babysitting the engine for at least 10 minutes, maybe 15 as it steadily chuffed along and it just seemed to go on and on. From that standpoint, it was an outstanding success in the chuffer category. I wouldn't have tried this today without Mike's suggestion of water cooling and the hose nearby. I thought about making a little water skirt sprinkler that surrounds the beer keg with a gentle rain or shower. If I stopped the water for too long the engine started to slow, and by directing the amount of water over the whole tank or part of the tank, there was a slight bit of chuffing amplitude control.
So this was my longest running snorkeler and probably close to the fountain of youth for a sustaining beer keg jam jar with water cooling.

[Mike Everman]

Faaaaascinating!

[Mark]

Here's a clip of me holding the camera with one hand and watering the keg with the other as the sun goes down. For the first time this year the mosquitoes have arrived. I think I must have gased them out of the azaleas, every now and then I had to blow them off my hands when they would alight. When filming you can't hold the camera to your eye, you have to look at the image on the back of the camera so it was all really half-baked - combating biting insects, watering, and filming. Oh!
Also a slighly longer snorkerl was used this time. I put about 2 quarts of fuel in the tank. I bet it would probably run slowly with 3 gallons for a long time, as the combustion is so sluggish, the slosh of fuel wouldn't be that disruptive unlike the one piglet snorkeler arrangement that will run like a bat out of hell. But how very difficult it is to get that snorkeler going. Maybe one day I will manage to capture it on video. It's something to behold.
I suppose I could have put a tincture of boric acid in the methanol with this run, the flame might have been more colorful flashing green. And I want to get the keg running much better than this. So many things to try. Good idea for the water cooling Mike. The beer keg gods liked that.
Also as pointed out in an earlier thread, at 60 psi rupture pressure, the 11 inch diameter top on the keg has a surface area of roughly 95 square inches. Thus a ballpark force of 5,700 pounds is the "breaking" point.
http://www.youtube.com/watch?v=w6ZlHX_B ... ather=True

[Mike Everman]

Boy, you can really change the frequency with the water. interesting! Speaking of pressure, I'd love to know what the average pressure is in there. If you had a fitting on there and a longish tiny tube to a pressure gage, it would give you a very stable average pressure reading. It would be nice to know. I'd expect something like 5-6 psi over ambient, so I doubt very much if you are flirting in any way with that 60psi limit.

[Mark]

Most days now are too warm and humid for the really perky screeches when it initially starts. Still, with longer snorkels it gives me a bit of a pause thinking about how suddenly methanol can backfire when partially confined. I was thinking the other day that a jam jar is kind of a short snorkeler, it just has the shortest exhaust tube. The neat thing about single port breathers with an exhaust tube is that you can really get them up and running so that they almost become a pulsejet running at half speed. To hear one is such a start to your senses, like the first time you here a pulsejet. It barks and shatters the air, so mystifying how it can do that "in -and-out" breathing through a single pipe.
I noticed one time when I got a false start with an 18 inch pipe/snorkel attached to a tank, I went to relight the thing a second time, (sometimes it flames out but will relight if you quickly try again without need of refreshment), looking down into the exhaust there formed a long swirling flame instead of an ejecting rush of hot gasses, the flame the length of the snorkel swirling and living inside the pipe but not touching the edges. I wonder what kind of air flow draws the flame while keeping it alive for 3 or 4 seconds, a gentle tornado in a tube?

[Mike Everman]

I've seen that too, like cold air going down one side of the tube and a long slender flame on the other. A neat continuous burn. Given a shake, it must start a poppin, I would think. It sure was a rare happening.

[Mike Everman]

I've got a 4' long Chianti bottle I've tried but no joy. Now I wonder where to cut the neck? I found a really good youtube tutorial about cutting glass bottles real neat and quick.