Odds and ends

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Mark
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Re: Odds and ends

Post by Mark » Sat Feb 03, 2018 3:10 pm

I see there are some funny new aluminum bottles out there.
https://www.youtube.com/watch?v=ljtff-5Wdk4#t=61s
http://420living.com/wp-content/uploads ... -cream.jpg
http://www.abcchapter.com/bottles/soda/ ... l%20v2.jpg

https://www.youtube.com/watch?v=RDJ9O--8o3o#t=11s
The forming process is reminiscent of clay in a hydraulic press.
https://www.youtube.com/watch?v=4h2Ed3BBAAA#t=42

Still fiddling with this beer bottle from time to time and trying some half-baked fueling method where it was hoped higher pressure fuel would travel to a lower pressure area. I can see the fuel gets pushed along when I go to light it angled at about 25 degrees tail up but it's either dampening feedback from too much fuel or it's sensing the aberrations made to it for some reason. The little 10-32 threaded fitting fits flush with the inside of the somewhat thick-walled snorkel tubing. The tubing of course is situated/held at the lowest point so that the puddle of fuel in the bottom of the bottle covers the press fit fuel line - just a hole that I forced the silicone tubing into near the bottom of the bottle.
Pulsating combustion can be very fragile or fussy as you may know. Even on a standard store-bought pulse jet it can take some effort to get it going if conditions aren't right. One time the tiniest tassel/wisp of Teflon tape was getting caught in the airflow of an exhaust on one design, which completely disrupted feedback.
Typically there's about 30 ml of fuel in the bottom of the bottle when starting these but for a 5 second burst to sustain probably/maybe just the fuel in a fuel line would be close to enough. Using the heat from the engine would be another way to pressurize the fuel flow or maybe get it to vaporize before being ingested or even butane - so many variables. I thought about putting the fitting a little bit lower down too in the neck region.
https://www.youtube.com/watch?v=8_qE0FW5MBs

Long ago I used that method to fuel my Logan, fuel was pushed from the terminal end of the jet to the side port and on one design the fuel went in just where the side port exhaust threaded to the combustion chamber. It was later that I took to introducing fuel right where the side port meets the combustion chamber, a little hole drilled in the side port to accept the tiny copper fuel line. In this photo it's running full grease and lasted about 10-15 seconds if I recall.
download/file.php?id=1484
Just a rev/review to sense how the primitive/non-idealized Logan sounded.
https://www.youtube.com/watch?v=W3mtr6DuXD0
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Mark
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Re: Odds and ends

Post by Mark » Sun Feb 04, 2018 12:33 am

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Re: Odds and ends

Post by Mark » Wed Feb 07, 2018 2:59 pm

Out of curiosity, these hollow brass candle holders that were going to be throw out were spritzed with methanol and lit at the narrow end via a threaded hole that held the "wax catcher" cup part on. The threaded hole accepted or matched well enough a typical spark plug thread and aside from that the candle holder also unscrews about midway as seen in the photo.
So the notable thing is that if you prime or swirl some methanol in the candle holder to coat the inside and light the small open end with a lighter, a terrific gunshot is heard - the propagation of the flame front quite brisk. It sort of strikes you as odd with such a large opening for the hot gases to escape or seemingly little confinement for the meager volume. It might be fun to try some long gradual cone shapes open at both ends as well like some of those vortex cannon shapes.
While the report of the candlestick holder is very sharp, it's also remarkably base. I was startled by the force of the sound, lighting it sideways and for the first time. Another thing is you'd be hard-pressed to hold it down on some flat surface and lighting from the hole in the top after spritzing it with methanol. It's got quite a kick in that mode.
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Mark
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Re: Odds and ends

Post by Mark » Fri Feb 09, 2018 12:14 am

So just a quick demonstration of the genie in a brass bottle effect or the sudden propagation of a flame front ...
Candlestick Holder with Methanol
https://www.youtube.com/watch?v=JfsXKl_TZ7c
https://www.filmous.com/static/photos/44774/4_midi.jpg
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tufty
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Re: Odds and ends

Post by tufty » Mon Feb 12, 2018 3:47 pm

You might find this interesting, perhaps even related...

http://bora.uib.no/bitstream/handle/195 ... sAllowed=y

Mark
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Re: Odds and ends

Post by Mark » Tue Feb 13, 2018 3:54 pm

That Norwegian thesis had some fun facts to ponder over. Funny that substituting one relatively inert gas for the other can make such a difference as when they switched the nitrogen to helium for example and that hydrogen doesn't produce as much pressure piling as a slower fuel.

I noticed on this can and bottle toy if the length of clear plastic tubing connected to the aluminum beer bottle was longer than what was used in this video, the little can that was sleeved in the bottle deformed severely, the concave bottom of the can was completely bent out to a convex shape and the end of the aluminum bottle where the can shot out of was torn and frayed like a rifle fired with an obstruction in the barrel, along with a deafening report. If you use too short piece of "lead up" tubing to the bottle chamber the bang is greatly reduce.
https://www.youtube.com/watch?v=kCppEmcRGCE

It comes to mind the platinum catalyst powder I sprinkled into a glass gallon jug one day, the specks of powder started to glow spontaneously like fireflies as they slowly floated down into the methanol vapor contained in the jug and then there was a deafening bang. While probably the interior point of ignition created the bang instead of the typical whoosh bottle effect, it seems by having multiple points of ignitions an explosion could be greatly increased akin to pressure piling by injecting a jet of hot gases and free radicals swirled and intimately mixed and shot into a secondary chamber.
https://www.youtube.com/watch?v=h3lS3TBuntw

Some tidbits from the article ...

In these situations peak pressure and rate of pressure rise can be several factors higher than in
comparable single vessel explosions. The term pressure piling or pre-compression is used to
describes explosions that show such characteristics pressure development

The computed values of the turbulence intensity in both chambers demonstrated that turbulence induced in the secondary vessel is a major factor
affecting explosion violence.

The turbulent burning velocity S has been shown to be a phenomenological meaningful
quantity as various experimental investigations indicate ...

4.7 Sources of error
Resonance effects
In general the fast burning mixtures showed considerable local variation often of periodic
character. Such effects could have been caused by resonance effect in the geometry ...

Condensed water
After a few tests water will typically condense on the inside of the vessel walls and may
represents a significant source of error. Water may evaporate from the warm vessel walls during
gas filling and the subsequent period of turbulence settling, altering the gas composition. Water
in the gas mixture may affect reaction mechanisms and heat capacity, whereas a small portion
of the water at the vessel walls may evaporate during the explosion. It is generally assumed that
the explosions will be to rapid for significant amounts of water to evaporate.


Orifice diameter below 5.6mm gave no ignition in secondary chamber.

Since the laminar burning velocity of hydrogen is
roughly 6 times that of methane, the time needed for the flame to arrive at the orifice is much
shorter. In the current geometry, the short distance, and thereby the small time span between
primary and secondary ignition did not allow for a significant amount of gas to flow into the
secondary chamber. Consequently the level of pressure piling was severely reduced.

The explanation for the strong dependency of volume ratio is twofold: First the larger scale of
the primary chamber result in a longer time gap between primary and secondary ignition, and
during this time gap more chemically bound energy will be transferred to the secondary
chamber. Secondly the higher volume ratio will in it self result in higher compression of the gas
in the secondary chamber

In experiments, radiation
will be much larger for rich mixtures due to the formation of soot, which have high emissivity.

In nearly all conducted experiments, methane gave higher peak pressure in secondary
chamber than hydrogen. The main reason for this is that methane has a slow laminar
burning velocity that causes late ignition in the secondary chamber and high peak
pressure. Due to of hydrogen’s high (laminar) burning velocity, less time is available
for pre compression of the secondary chamber and consequently peak pressures are
lower for this gas. This trend is expected to be valid for all geometries resembling the
ones used in the experiment, but might not be invalid for large-scale situations

Some important geometrical factors are:
• Volume ratio between vessels
• Cross-sectional area of connection
• Scale
• Shape of vessel
• Point of ignition

The presence of “inert species” for example nitrogen or solid surfaces pose further
complications. They are generally not recognized to participate in the reaction, but may have a
catalyzing role in some reactions and may affect the process as heat sinks or alter diffusivity.
The replacement of nitrogen with helium in a methane-air mixture will for instance triples the
burning velocity (Glassman 1987).
http://bora.uib.no/bitstream/handle/195 ... sAllowed=y
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Mark
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Re: Odds and ends

Post by Mark » Mon Oct 14, 2019 10:04 pm

I bought one of these witch glass milk bottle jars today for 69 cents at a thrift store. These have always taunted me because they seemed potentially a no-build jam jar jet par excellence. The height is about 4.6 inches or 118 mm. The lid 2 inches in diameter or 50 mm. When the silicone grommet is removed from the lid, the very neatly cut hole diameter is exactly 10 mm according to my digital caliper.
Just now I fired it up and behold it put a smile on my face, running fast and strong with a really healthy sound. If you ever see one of these jars with a straw and pre-cut hole in the lid, I'd highly recommend them. I've seen them before with various artwork in this size at the dollar stores. In fact the white label stuck to the bottom of the jar lists the price at 1 dollar. Filled to the top the volume is 200 ml.
The off-the-shelf jam jar jet has rekindled my interest in these simple toys and I feel certain the ready to go shape would have amused Reynst if he was still alive.
https://mercari-images.global.ssl.fastl ... 1570670718
https://mercari-images.global.ssl.fastl ... 1570670718
https://i.ebayimg.com/images/g/RUYAAOSw ... -l1600.jpg

"If you’re over the mason jar trend, consider ..."
https://partyideas.craftgossip.com/glas ... r-parties/

I found these jars for sale at Target for 1 dollar and bought a few more. Really a nice running novel jam jar jet.
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Mark
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Re: Odds and ends

Post by Mark » Sun Oct 20, 2019 1:06 pm

A few more designs of the 4.5 inch tall store-bought jam jar jets. The sides get hot very fast so some sort of design where the internal flame is more focused or narrowed, or sleeved with an internal heat shield or partition wouldn't hurt.
https://spookylittlehalloween.com/wp-co ... ween29.png
https://spookylittlehalloween.com/wp-co ... ween31.png
https://thekrazycouponlady.com/wp-conte ... 218044.jpg
https://di2ponv0v5otw.cloudfront.net/po ... 613581.jpg

These larger jars might be a little perky with the hole to jar size but they could work, but eye protection might be a good idea having blown the lid off a few jars myself. Spellbinding wonderment. ha
https://m.youtube.com/watch?v=g0ExoAJCbvg
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Re: Odds and ends

Post by Mark » Thu Oct 31, 2019 7:19 pm

Some prototype experiments with small snorkelers and other tidbits are pictured here. There're 7 fused quartz sleeves and fused quartz crucibles in the one photo. One is not even an inch tall but I haven't found a lid and way to try to run it yet.

The two quartz crucibles with the blue and green silicone rubber bands rev up most energetically but they don't sustain. It's pleasing how loud they buzz even as small as they are. The other parts to them are aluminum arrow tubing and tiny steel funnels. The arrows were press-fit using a tubing expander but the aluminum arrow shafts are so hard and brittle that they just crack instead of expand so then by heating them with a torch to anneal them they then behaved. I had to hold the prototype quartz snorkelers together with a gloved hand because they have a pretty strong kick when lit from the tip after priming with methanol. On the plus side they are easy to air out, just separating the funnel and snorkel section from the crucible each try. They make a very promising rev but then just die suddenly, perhaps the burrs or rough transitions from funnel to arrow shafts are not smooth enough or maybe a larger size snorkel would get them working. Any aberration/ridge or indentation at the transition from the snorkel to funnel can really mess up air flow. But to hear the speed and zest of these small shapes is very motivating.

Some mention of the jam jars with straws, they are ready to run jam jar jets bought for a dollar. Just remove the straw and grommet and put in just enough methanol to barely cover the bottom. In this way the run is steady and smooth, and you aren't going to want to run them too long anyway because they are merely or most likely going to crack if you do. The hole is very neat and centered for you - not much effort to do this effect other than buy some methanol. There's also a bamboo container that arrived from China today with a lathed, snug fitting bamboo lid.

In the past I ran some skull jam jars but the lids didn't have gaskets and the hole for the straw in those larger jars didn't work/too small so I used a spaghetti jar lid and some other kind with a larger hole that I drilled. I plopped my lighter on the lid to stop them from getting to hot but you can't really see that.
Happy Halloween
https://www.youtube.com/watch?v=Z-oOYF7EDYk
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Re: Odds and ends

Post by Mark » Fri Nov 01, 2019 1:23 pm

Mark wrote:
Wed Nov 08, 2017 6:28 pm
I was trying to think of something the little quartz vial could do, say to cause motion in bees or hummingbirds, a little kinetic art diorama of some sort. There's several designs of fidget spinners, they could spin up under the power of these tiny quartz jets, but nothing really enthralling has come to mind yet ... just a simple wire thrift store stand and a Christmas ornament, right up there with the carrot car of half-baked ideas.
The photo
download/file.php?id=15402&mode=view
download/file.php?id=15400&mode=view

Looking back at this post of nearly two years ago it dawned on me this little jam jar jet that might have been used to cause motion in the hummingbird, blowing or buffeting the figurine as if it were interested in a flower, has come to fruition in a sense.
download/file.php?id=15511&mode=view
download/file.php?id=15394&mode=view
https://youtube.com/watch?v=VgMJac_amhk
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Re: Odds and ends

Post by Mark » Sat Nov 02, 2019 6:30 pm

This being Day of the Dead and all ...
Day of the Dead Jam Jar Jets
https://www.youtube.com/watch?v=vY8vpUiFins
https://en.wikipedia.org/wiki/Day_of_the_Dead

And some Halloween jars
Store-bought Jam Jar Jets
https://www.youtube.com/watch?v=GEgXyf2NevM
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Re: Odds and ends

Post by Mark » Tue Nov 05, 2019 4:07 pm

I was trying to figure a good/elegant way to hold the jar without much effort or the risk of melting silicone and it sticking to the jar so I just did some fused quartz chopsticks or 4 mm quartz tubes that were intended for military infrared flashlights/ the weird stuff you find on eBay.
It surprised me the first time before videoing. I started it and at an even less oblique angle (a more optimum thrust angle than the video) and it was not expected to go very fast but I was holding my hands wide open in a vain attempt, in case the jar reached escape velocity I might save it. Because there isn't much friction the slightest force allows it to go unsettlingly fast for the questionable chopstick fingers.

As an aside, I bought the shape I designed for 30 dollars plus 10 dollars shipping. I noticed the price has gone up from a previous hike of 40 dollars plus shipping to now 49 dollars plus $9.99 shipping or best offer. You can see the listing if you search "Fused quartz tube with flat bottoms, one 7mm hole in the center of one bottom". Funny that they would try to offer the shape. How many people out there would be searching for a fused quartz tube with flat bottoms, one 7mm hole in the center of one bottom I ask?

Jam Jar Jet Motion Test
https://www.youtube.com/watch?v=tapt0Vzv1Eo
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Re: Odds and ends

Post by Mark » Wed Nov 06, 2019 8:03 pm

With 2 milliliters of methanol and some patience I was able to get some cycles. Ideally it could be cooler and less humid for maybe double the time seen here. At this rate my 2 gallons of methanol should last for some time. ha

Miniature Quartz Jam Jar Jet Spinning Slowly
https://www.youtube.com/watch?v=AWZLWBXqSn0
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Re: Odds and ends

Post by Mark » Fri Nov 08, 2019 1:37 am

Maybe tomorrow if the humidity is down, these aluminum flashing and copper foil lined 12 ounce jam jars will last longer than without the foil. The fuel in the bottom might cool the foil somewhat or rather the heat in the foil transfer some to the fuel. And perhaps the copper foil will produce some green flames, who knows. Because the foils are kind of stiff but easily shaped, I was able to get the inside open edge of the foils to lay flat without dog ears and such after wrapping them around the outside of the jar and then constricting them making them kind of springy when inserted. Ought to be interesting to see if there is any benefit. As was suggested a tray in the bottom would probably be something to try too.
One thing about these 12 ounce jars is they're cylindrical and the neck of some tappered jars might tend to absorb a lot of heat as the flames are channeled upward and crack quickly, but there are so many variables. I cracked a 6 or 7 inch tall milk bottle in three or four seconds the other day, not cracking at the fuel level like some but all over and up by the neck.
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Re: Odds and ends

Post by Mark » Sat Nov 09, 2019 10:24 pm

I got out this old syringe I'd run many years ago. A somewhat similar ear syringe ran 7 minutes when submerged in water. I had one of those flimsy thin aluminum pie pans with a center hole cut out skirted over the syringe to block the steam from the water bath getting sucked into the barrel of the syringe and also a soft breeze from a small fan - a lot of hovering just to keep it running that long.

Jam Jar Jet Syringe
https://www.youtube.com/watch?v=6xpZYVAwkzI
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