metal jam jar experiments

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Bruno Ogorelec
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re: metal jam jar experiments

Post by Bruno Ogorelec » Wed Jun 08, 2005 5:42 pm

Princess, that was one awesome photo! I miss your screams and yelps. May the gods of pulsation be with you. Have fun.

mk
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Re: re: metal jam jar experiments

Post by mk » Wed Jun 08, 2005 9:35 pm

Thanks for the measurements again, Ross!
Rossco wrote:[...] I dont have an accurate count to date, although there is a record possibly in the making. [...]
Yeah, that just looks like a real runner. Seems to fit the "Rossco-scaling-factor" -- from "EDK4X" engine topic.
I've two even smaller ones (guess!) of about the same shape that are real runners, too.
Greetings to "pj princess".

So a 3.5 ratio you say? Well, I'm thinking of extending the current piece of pipe or using a new one up to 4:1 or even longer and start cutting back again. Extending might be a kind of an instable struckture.

I've still laying a nice long cone laying around -- small ID about 35mm, large ID about 80mm, length about 600mm but I'll have to measure the length again, don't quote me. It really looks to be just right if a 35mm ID hole would work for gasolene then.

I'll let you know if something happens.
Rossco wrote: [...] 20mm diameter slightly less internal maybe 19mm. [...]
BTW What does this phrase refer to?
mk

Rossco
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re: metal jam jar experiments

Post by Rossco » Thu Jun 09, 2005 5:38 am

Rossco wrote:
[...] 20mm diameter slightly less internal maybe 19mm. [...]
BTW What does this phrase refer to?
Thats the diameter of the tail pipe. Its just straight pipe, of about 20mm.
Fits down the hole leaving plenty of room to breath.

I did cut out the hole again last night, and it still runs with the pipe. Didnt play with it that long to see what else has changed.
When i do, i think that ill take it out some more, it still blasts exponantialy harder untill cut out, with the pipe in just the right spot. You have to adjust it to keep it running. What im aiming for, is getting it to sustain a run at this sweet spot with out over running.

Edit: The cone that you mention, would i think be put to better use in another style engine. Ive found that the long cone top is quite bad for operation. I think that was the main issue with the one i made at the meet. The cone turned out to be much longer, steeper angle than mine here. I would go for a slightly lesser angle if i were to build another one, see how that goes.

Rossco
Big, fast, broke, fix it, bigger, better, faster...
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//PJprincess//
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re: metal jam jar experiments

Post by //PJprincess// » Wed Jun 15, 2005 7:40 am

hey guys going to try and reply it has already kicked me off!!!
yeah i've been haviong alot of fun with the jars... however i dont know what my neighbour thinks as i still scream and get excited every time!!!
Ive got several types going now ranging in size, shape, and even material.
Ive got a collection of plastic and glass!!!!
And the bigger the better!!!
Ive found a bigger hole works better and mine like to get a bit warmer before they run properly, and they all have a mind of there own!!! So its good to talk to them and encourage them or they get a huge case of PMT and bad mood swings!

I see everyone is making great progess since the meet. Yes I am keeping an eye on you all!!!!!

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re: metal jam jar experiments

Post by Dave » Wed Jun 15, 2005 11:23 am

PJP

I did a couple of Jam Jars for my daughter, only to find that she had a reaction similar to yours. We worked with small glass jars for a while, and then moved on to 2 liter plastic soft drink bottles. Those really get her going: They don’t really pulse, but give out a single long shriek and fly! Just a 6mm hole in the top, a few shots of “squirty stuffâ€

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re: metal jam jar experiments

Post by //PJprincess// » Thu Jun 16, 2005 1:02 am

Dave
I have also been working with similar bottles and blasting them around my kitchen.... quite amusing...
not sure where to take them next, as you can see the 'power' the plastic bottles have (also because they are so light) but it would great to get the metal ones to move also (not quite so much though as someone may get hurt!!!)

Any ideas for what to try next... that doesn't involve welding!!
Christie

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re: metal jam jar experiments

Post by larry cottrill » Thu Jun 16, 2005 3:48 am

Princess -

Try to get the little CO2 cylinders to work [empties, of course] - I've never heard of any successful 'jam jar' runs of those yet. I think you can drill out the pierced end to any size up to about 5 or 6 mm [which I'm sure is too big for good operation]. They're high-strength steel, but have a fully rounded nose and don't weigh much, so other than breaking a window or two, they shouldn't be too deadly [wear eye goggles, though, if you really get them to work well enough to send them flying!]. The 12 gram ones may be too long, but there are 8.5 gram ones that are more 'jam jar' proportioned.

L Cottrill

mk
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re: metal jam jar experiments

Post by mk » Fri Jun 17, 2005 7:19 am

Rossco and all the others following the topic, some news from Germany now.

I wrote this message on June 14, because I just didn't know how long it would last to get the DSL connection working again. There was an awful thunderstorm on the mentioned date happening in the time of late afternoon up to the evening. Probably the reinforced rest of a Florida hurrican. It's pretty usual that these hurricans wander up north the US east cost, loosing their strength by a rel. large percentage and after that linking to the jetstream, where they're getting reinforced again, because of the overall high and low pressure zone distribution and the resulting wind directions on the earth and the resulting wind directions, and also because of the larger coriolis force -- hurricans need at least 12° north or south for their creation by enforced air mass rotation. Then old Europe is being visited by a cyclone. A rotating low pressure zone, with warm and cool fronts following each other and moving around the low pressure zone's center. Then we're getting some nice warm weather for a few days, which ar usually follwed by one to three days of rain and a temperature drop of quite some degrees C. After that again some nice days are following, but the temperature are staying "chilled". And suddenly, mostly in the afternoons, the temperatures and the humidity are rising, fat and dark clouds are appearing and a thunderstorm is being formed. Then there are some hours of really tough rainfall following. Mostly the next day is nice and warm again until the next cyclone arrives or the weathers stays as it is if a high pressure zone settles down for a while. Then there is a special case, when the second cold air front rotates faster than the first one and so the first cold front gets cought from the second one. Then the intermediate warm front is being liftet up from the ground -- it's called an occlusion. When this case appears, temperatures are staying relatively cool, but it keeps raining and thunderstorming for almost three or four days. Well, this cyclone phenomenons mostly or rather usually appear in spring and autumn.
But on June 14 it got warmer, cloudier and more humid all the day long. Then at about 7 or 8pm MESZ (CEST? -- central European summer time --) lighnings could be seen at the horizon and in the clouds and thunder could be heard. Just half an hour later lighnings in the clouds and from the clouds to the ground appeared every couple of seconds. This lasted for about two hours! Lightnings and thunder just all the time. Amazing and a bit frightening. Well I was wearing ear protection, because I finally managed to to enlarge the large Reynst combustor's hole up to 37mm ID, but more later on. Also rain began to fall very hard. I haven't seen such masses of water in such a short time for years if I have seen it ever. And then BANG a lighning just went more or less straight into the antenna mast of my father! I haven't seen a lighning from such a small distance only. Amazing. Really amazing. But the following thunder wasn't much louder than the one of a lighning which went into a tree, house or whatever a few kilometers away. I'd say the sound was not a deeper frequency grumble, but rather a short noise of higher frequency. Well, due to the impact I've fused some lights and, of course, the DSL router blew up again. Damn it! I unplugged the computers and stuff from the power source, unplugged the splitter and within the router and the modem, but from the telephone line only! Man, all the ******* trouble again. I'm just going crazy. However, back to the topic.


The smallest and the largest diameters of the internal cone structure are still larger than the hole ID. Maybe 45 or 50mm up to 55 or 60mm. I don't have the measurements anymore. It is also deep in side the combustor, let's say about in the middle.

Now having a hole ID of 37mm the combustor does not sustain in jam jar mode -- without a tuned pipe -- anymore. At least when refering to heavy fuels.

I tryed the diffuser with nearly no success, so I still used the stuck together pipes of about 3.25:1 length ratio (see attached pictures). A nice thing to mention is that I could try protruding pipe settings now from just flush with the lid up to flush with the bottom. Herein I have to mention that the copper pipe is 28mm OD and the steel pipe 25 (at the treaded end) and 26mm OD in general. Also it didn't matter wich side I introduced now, rather the larger diameter down was found out to work better than the small diameter down, what is just the opposite of the examinations/observations I described in a former post. I'm about certain thatk that the small diameter is just to restricting to the flow, especially when the cutting edge remained without any smothening work, using a larger ID (than pipe OD) hole and protruding pipe settings. Thus the following observations were made by using large diameter down or small diameter up positioning of the pipe.
In the same case protruding settings for the pipe have been found out to work best so far. However, I couldn't try protruding diffuser settings jet, because the hole is still to small for this one.

Fueling methode was the well known pool and as fuel was used the famous oily, old gasolene mixture with some liquid BBQ coal enlighter and very wee bit of ethanol. Let's say two-stroke oil to gasolene to liquid coal enlighter to ethanol about 1:25:15:1, but that's just a guess.
Also with a grwowing hole area the demand for a more energetic fuel and a better mixing action was discovered. Thus putting a pool into the combustor and then rotating it 90 degrees to one and the other side, so that nearly the whole entire, inner wall surface is covered with fuel, has been found out to work quite nicely.
As result of the hole enlarging action I had to disassemble the lipfeed feature partially. The lid is about 1.5 to 2.0mm thick now. Maybe a ring-shaped "swizzle stick" could be used instead later on for propane vapore fueling.

As mentioned I tried different pipe protruding settings always changing the position just a couple of millimeters.

The best results have been achieved by using a rel. cool pipe -- it get's really hot now! -- being parallel, inline or only slightly angeled to center line. I think I need to buy a new and longer copper pipe to reach a 5 or 4:1 lenght ratio and start cutting down again.

The best working self-air-refreshing work, by just lightening the the fumes at the hole with or without the pipe in place, was achieved from protruding length of 1/2 times the copper pipe OD to 2 times the copper pipe OD. It needs to be mentioned that the internal structure begins -- measured from the lid -- at about twice the copper pipe OD length.
Pipe potrusion further into or through the internal conical structure have not shown any advantage. The resonant behaviour of the assembly got worse with "further in" and flush to "further out" settings of the pipe.
When refering to the locking behaviour only, it can be said that the best results have been achieved by further decreasing the possible distance extreme values regarding to the upper edge of the internal structure. Namely with the pipe protruding about 1 to 7/4 times the copper pipe OD into the combustor. It was felt that a certain distance between the pipe and the internal structure is advantegeous, to avoid acoustic coupling or something internal vortex reverse flow related, but setting flush edge planes or setting the pipe just a few millimeter down into the conical structure still worked somehow, but didn't show real locking behaviour and a decrease in self-air-refreshing "efficiency" leading to the need of "forced refreshing" after a couple of getting worse and worse short runs.

All in all one short and completely locked run occured with a handwarm pipe and a slightly warmer combustor and a wet -- fuel, of course -- wall surface. The pipe was inbetween 3/2 and 7/4 times the copper pipe OD protruding into the combustor, about in-line with the center line.
The combustor now rather sounded like a long, large volume pulse jet, simmilar to Rossco's meet engine. Perhaps more intense in its sound peaks and for about 5 to 8sec. The entire inner volume of the combustor was filled with yellow flames only some flame peaks and some dark smoke were comming out of the nearly concentric "rest hole rim", formed between the pipe and the hole. During the locked run the combustor and the pipe became amazingly hot.

Conclusions.
It has been felt that the internal cone structure needs to be set further towards the lid, just similar as presented in the drawings showing the final oscillating combustion chamber progress of F.H. Reynst. Then a tuned pipe or a diffuser section could be assembled in a non-protruding or lid-flush way, also similar to the drawings of the large Reynst combustors.
Another important thing is that the hole still seems to be to small when locking appears and forces/supports a rise in the amplitude, what leaded to the usage of liquid BBQ coal enlighter. It has been chosen, because no other, heavier oil stuff has been available at the time being. Further experiments might happen with diesel and/or a mixture of the old gasolene and diesel. Parrafine might be a solution, too, if it is not felt to switch from "fuel pool" fueling to "propane lipfeed".
But before the locking behaviour or rather amplitude rising -- what really happens smooth and for quite some time, you can really notice it -- running mode was achieved the hole was felt as being to big, but a variable pipe protrusion length overcame the problems nicely.

Enough stuff for now, IMHO.

PS If the post does not feature any attachements, I'm going to post them another day.
Attachments
diffuser_and_pipe_for_large_Reynst_combustor.JPG
stage of development on June 14 2005
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diffuser_and_pipe_w_ruler_detail.JPG
stage of development on June 14 2005
diffuser_and_pipe_w_ruler_detail.JPG (331.14 KiB) Viewed 10621 times
large_Reynst_combustor_37mm_hole_and_inner_cone.JPG
stage of development on June 14 2005
large_Reynst_combustor_37mm_hole_and_inner_cone.JPG (319.94 KiB) Viewed 10622 times
mk

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re: metal jam jar experiments

Post by mk » Fri Jun 17, 2005 7:23 am

Oh, just some more pictures.

And I got a new piece of 28mm OD copper pipe. One meter long. Well see.

BTW the internal cone structure is hold in place by two struts.
Attachments
large_Reynst_combustor_hole_w_ruler.JPG
stage of development on June 14 2005
large_Reynst_combustor_hole_w_ruler.JPG (249.28 KiB) Viewed 10621 times
large_Reynst_combustor_w_ruler.JPG
stage of development on June 14 2005
(337.21 KiB) Downloaded 653 times
mk

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re: metal jam jar experiments

Post by mk » Sat Jun 18, 2005 5:53 pm

I tried the one metre long copper pipe today briefly.

Fueling was done via the "fuel pool methode". The fuel pool consisted out of the old gasolene - two-stroke oil mixture only.

The result: Now the combustor really locks! I'd guess at around 100Hz but don't quote me here. The Sound became more intense and "peaky", though, what means the single pulses appeared sharper and more intense. And I'd guess even more intense than they were as the combustor self-sustained on ethanol and the small hole only.

Locking appears at least for a short time, and then self-sustained operation quits instantly, rather with rising amplitude, which becomes too intense somehow for further a operation.

The formerly mentioned protruison lengths where proven, despite the combustor also liked further potrusion more.

Also the about in-line or parallel alignment of the combustors and the pipes center lines were proven again.

Possible failure sources, which appear to me actually:
- insufficient fueling
- wrong shape and location of the inner, conical structure
- pipe too long
- hole still too small

We'll see.
Attachments
protrusion_marks_best_locking.JPG
protrusion_marks_best_locking.JPG (181.49 KiB) Viewed 10603 times
large_combustor_and_pipes.jpg
(326.9 KiB) Downloaded 702 times
mk

Bruno Ogorelec
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re: metal jam jar experiments

Post by Bruno Ogorelec » Sat Jun 18, 2005 6:13 pm

Wow, Marten, does that mean you are a step away from the first modern Reynst pulsejet engine? This is very exciting. keep us posted on every detail!

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re: metal jam jar experiments

Post by Graham C. Williams » Sat Jun 18, 2005 11:18 pm

Dear Marten.
You must take control of the Thermal gradients in the motor. At least in the early stages the pot is a 'Thermal Breather'. See Nicks Videos of his 'Pot'.
You'll need some water cooling.
http://www.pulseweld.dsl.pipex.com/page3.html

Regards
Graham

mk
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re: metal jam jar experiments

Post by mk » Sun Jun 19, 2005 9:42 pm

BTW I think it's pretty weird that I got caught by the tuned Reynst combustor layout, despite I'm really not a friend of annular designs. I pointed it out at the meet several times, didn't I? Perhaps I'll need to revise some statements in the future.


Thank you Graham for the link and mentioning the thermal breather issue!

Yeah, the thermal breather stuff makes sense indeed, because the combustor likes to work best when not completely heated up. What can also be said for the tuned pipe. As soon as there is a certain temperature gradient appearing, the locking is pretty hard to achieve. As soon as the pipe heated up completly, so that the temperature gradient was reduced, the locking-up process happend much easier again. But for short times only, too.

I still feel that the "fuel pool" is not a god way to fuel the combustors nicely. As soon as the waals are dry, ypu'll get an under-leaned top and an over-riched bottom region. Nasty. Also mixing time seems to be unadvantageous then.

Today I gave a mixture consisting of liquid BBQ coal enlighter and ethanol -- maybe about 1:1 -- a short try. Well, BBQ coal enlighter failed in the case of the initial trigger, so ethanol was added -- I didn't want to use gasolene while being dressed with good cloths and having had the plan to go out.

A typical ethanol fueling phenomenon occured, though. Namely: The combustor needed to be rel. cool for a successful start. But, IMHO, the BBQ coal enlighter made for the relatively long duration of the locked-up operation and perhaps for the sharp blasts as well. Pretty cool. My dad was outside and meant it sounded pretty "dangerous" -- hehe. I'd guess the self.sustained run was about twice as long as the ones I got before. That again supports Rossco's conclusion: "Pull out the grinder again".

But also with the mentioned fuel, the protrusion length was proven to work well again, slightly leaning to a "more out" side, when compared to all the gasolene mixtures. Excessive protrusion changes only need to be made when doing the self-recharging by the tuned pipe's chimney effect.

However, I'm currently convinced that a) the internal cone structure needs to be moved upwards, more to the hole, b) the hole ID needs to be further increased, c) a better fueling method needs to be established and d) the tuned pipe needs to optimized (shortened), maybe to a length inbetween 3.5 and 4.0 times the combustor length.
A cooling feature (e) would be nice, but also hard to add at the moment for the actual combustor layout. Currently the fueling methode (c) and the internal structure layout and placement (a) are kept as they are set for the moment.


Any input?


PS I recorded a video showing the throttling on AT 2000 (70% butane, 30% propane) with the "claw needle injetion" for my small glass jar. A tiny pool of ethanol was still needed, though, to generate a better re-ignition stability and for starting, of course. It's some Mb large, so just email me and I'll send you the video.
mk

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re: metal jam jar experiments

Post by Bruno Ogorelec » Mon Jun 20, 2005 9:52 am

Marten, could you please make a drawing with dimensions of the pot and the pipe in the layout that worked the best?

mk
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re: metal jam jar experiments

Post by mk » Mon Jun 20, 2005 10:08 pm

Bruno, I'd have to cut it in two halves to do that. I just TLARed the combustor more or less and forgot to write down the measurments.

But you can get an idea of the whole assembly by measuring the things in the picture, can't you?

The single larger copper pipe is one meter long and, just as the other copper pipe stack, 28mm OD.

The conical, internal structure should be about 60mm to 70mm long and placed just in the middle -- length wise -- or slightly towards the top, when refering to the combustor only, but I just don't know it anymore.

Come on guys! Nobody interested in doing some Reynst work (again)?
mk

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