Odd Metal jars

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PyroJoe
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Re: Odd Metal jars

Post by PyroJoe » Mon Jan 09, 2012 5:32 pm

What are the dimensions of the one labeled "mathew", that runs like mad!

http://www.youtube.com/watch?v=32OY8Y9n ... digest_sun

kevin lee
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Re: Odd Metal jars

Post by kevin lee » Mon Jan 09, 2012 6:38 pm

PyroJoe wrote:Far from everything has been tried, I say give it a go. My speculation is the water has a high enough density it would interfere with the pumping effect of the tail. Instead of the pressure from the CC driving the tail pump, it will dump the pressure out the intake. The first cycle would be good, but the following cycles would suffer from a clogged pump. If enough average positive pressure could be maintained in the exhaust and the first cycle cleared the pump, it may very well run fine!

Actually during the weekend i found a thread about this question. I havent read through it yet because its slightly technical, but i did read the first page and it could well be possible (if the tail is JUST under the water level - pressure increases with depth).

I think ill spend more time with some basic things first and move on sometime in the future!!

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Re: Odd Metal jars

Post by kevin lee » Mon Jan 09, 2012 6:47 pm

PyroJoe wrote:What are the dimensions of the one labeled "mathew", that runs like mad!

http://www.youtube.com/watch?v=32OY8Y9n ... digest_sun

Haha Thanks Joe, i was very happy when it fired up like that for the first time!!

cc = 155mm long x 64mm id
inlets are 2 x 8mm holes (drill snatched on 1 hole as can been seen by the odd shape blue flame in above vid)
exhaust is 720mm long x 14mm id

convex port plate and concave bottom plate

Hope that helps!!

The second one that i started to build is proving funky too light . iam actually seriously tempted to try and make it into a pj and run it on propane. i know 14mm id exhaust and 28mm id combustor will be a pig too start and run but iam up for the challenge :)

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Re: Odd Metal jars

Post by kevin lee » Sat Jan 14, 2012 3:00 pm

i Have just recieved a super sensitive valve designed and built by Nick, iam hoping to have a thermo-jam running for longer than a minute, 1 minute is my pb haha

not sure if ill be attempting to feed the thermo-jam more methylated spirits into the pool or maybe propane directly into the cc, in the path of the inlets.

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Re: Odd Metal jars

Post by kevin lee » Tue Jan 17, 2012 8:43 pm

here is just a concept idea that iam trying out, need to make things alittle more 'proper' before ill have any decent results. i need to make a fuel flow control gubbins. my plan is to just drill some 7mm mild steel rod with a 3mm hole down the middle then pop an m4 grub screw in through the side, then i can wind the screw in or out to adjust the flow. pinching the pipe isnt accurate enough and isnt easily reversible.

other things that need sorting are proper metal fuel line from the fuel cell to the thermo-jam, because the plastic pipe melts and leaks alittle. and also sort all leaks so that i dont get flame outs ect.

http://www.youtube.com/watch?v=mQSDKoj_ ... ature=plcp

general idea looks like it works :D
Last edited by kevin lee on Wed Jan 18, 2012 12:19 am, edited 1 time in total.

metiz
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Re: Odd Metal jars

Post by metiz » Tue Jan 17, 2012 8:49 pm

That's basically a full on pulse-jet without an intake, good job. If you're running on liquids, the engine will need some cooling for longer runs. It needs to be hot, but not scorching (there's a challenge for ya)

Once the engine is running and the liquid fuel's almost out, try switching to gas. Gas likes hot engines so no need for cooling then
Quantify the world.

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Re: Odd Metal jars

Post by kevin lee » Tue Jan 17, 2012 11:45 pm

Thanks mate and thanks for the tip on cooling, something to think about. How hot is hot and how hot is scorching? The last few times that i ran it flat out with the extra fuel it has glowed orange the entire length of the can! Thats scorching yeah?

I have tried to run it on gas, i think i may have some video, ill try and upload some if i do. but it was a bitch! I have a super fine gas valve that is capable of the job but iam not entirely sure how to inject the gas.

The fuel tube that you see in the video is a 3.2mm stainless pipe that runs through a hole in the port head and dips down into the fuel pool, this engine doesnt like to run standing up at all, probably because of the concave bottom of the can. The fuel tube glows orange inside the can.

Have you got any tips regarding injecting gas into it?

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Re: Odd Metal jars

Post by kevin lee » Wed Jan 18, 2012 12:16 am

Here we go, gas attempt with the thermo-jam.

http://www.youtube.com/watch?v=8krnOeqlQGk

I think the methylated spirits are keeping it running but a whiff of gas was helping to pick up the pace, in my opinion it will take some thought to get it running for long periods of time on gas. Iam going to keep on experimenting with the meths vapourizer fuel cell on this current thermo-jam and build a new one based on what i have learnt so far, i will probably build it with better geometry so that it is closer to joes recipe. This does mean i will probably end up building an actual tiny pulsejet that starts on meths and switches over too gas.

Tips and ideas welcome, these little things are fun and much quieter :D

PyroJoe
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Re: Odd Metal jars

Post by PyroJoe » Wed Jan 18, 2012 5:31 pm

Thats really good stuff,
for now the only things I would try would be to slightly reduce the CC volume and add augmenter sections over the intake ports. This should increase the CC pressure and yield a better conversion of the pressure to mass flow.

If possible use the elevation of your fuel tank to attempt to overcome the average pressure of the CC.

If it is built closer to the recipe, the frequency will shift much higher and it will most likely out run the fuel supply, at least thats what I've seen in the past.

kevin lee
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Re: Odd Metal jars

Post by kevin lee » Wed Jan 18, 2012 9:56 pm

Thanks Joe and thanks for the tips 8)

The inlets are 8mm, should i use 8mm id augmentor tubes? and do you have any recomendation on gap between augmentor and inlet? i will make it adjustable and it would be nice to have a large enough gap for a match to fit for ignition. do you think flares at each end are a good idea? i guess testing will give me the answers i need :mrgreen:

I have been thinking about adding an expanded tail section, but not sure how it will affect this engine. Any ideas? Will this aid the exhaust pumping or will it just move me more toward higher frequencies and fueling problems.

Iam not sure how i could elevate the fuel tank without changing the fuel system entirely! At the moment iam using the cc heat to get the fuel moving. I wonder whether i could use a cc tap and a one way valve or check valve to equalise the pressure in tank with the peak cc pressure. Then the heating of the fuel will, or should the way iam thinking, apply a higher than peak cc fuel pressure. To be honest though i think that in one of the videos, that i posted, it was getting to much fuel. Although that theory is kinda lame because its running off of a fuel pool.

Actually its obvious when it has too much fuel because some fuel gets ejected from the exhaust 8)

The exhaust is extremely long in calibers, its about 51.5 cal lol. I have been considering whether this has a draft effect!

This is all very interesting stuff, ill keep on tinkering with these little thermo-jams. Wheres Ghrey :)

Ill look into a smaller cc version but ill also pay attention to your advice about higher frequencies and fuel problems.

Thanks
kev

ps. do i build a dragster or drag boat for this ha

PyroJoe
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Re: Odd Metal jars

Post by PyroJoe » Wed Jan 18, 2012 10:57 pm

51.5 calibers makes it a "fraction engine", it just has plenty of extra CC volume. Fraction engines are typically more fuel efficient, and lend themselves to fuel pool operation. The pumping action tends to create a drift velocity that helps to sweep the CC of humidity. Much like a draft effect without needing to be vertical.

I would suspect a tail expansion to decrease the drift effect and raise the frequency. Definitely do not expand the first 44% of the tail, as thats the most critical portion.

Augmentation is probably a test and see, but i would start with a diameter only slightly larger than the intake ports. The gap I would make the same as intake diameter and try adjusting. The goal is to capture the escaping pressure and convert it to mass flow within the augmentor. It helps containment, and will also reinforce the mass thats accelerating down the tail pipe. Running a valveless engine without an augmentor is like running a piston engine without the head bolted on.

Also a augmentor will create a better low pressure swing during the low pressure intake cycle. Pulse jets may some day achieve many atmospheres of positive peak combustion pressure, but be assured they will never go below one atmosphere on the low pressure side. :wink:

I say we follow Ghreys lead and do drag boats. 8)

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Re: Odd Metal jars

Post by kevin lee » Thu Jan 19, 2012 10:40 am

Here is the fine control valve that Nick designed and manufactured, works well but I need to perfect my techniques :)

Image
Image

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Re: Odd Metal jars

Post by kevin lee » Thu Jan 19, 2012 10:54 am

PyroJoe wrote: I say we follow Ghreys lead and do drag boats. 8)
Awesome, Iam more than up for a fun challenge. Although I think you will destroy me with your knowledge and experience ha

Here is my secret weapon/concept that I have been pondering over. Not so secret anymore Haha
Image

Iam likely to get carried away and build a sinker though.

Drag boat opens up the chance to try 'pop pop' technology, dipped/submerged tails, water injection and some other things on my mind.

Thanks for the tips and great explanations, you are saving me hours of reading and Iam learnings stuff that I haven't even considered previously 8)

I'll make adjustable augmentors and ill leave the exhaust alone for now.

Lots of things too try out :D oh I may start a thermo-jam thread too stop this one going off topic.

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Re: Odd Metal jars

Post by kevin lee » Thu Jan 19, 2012 11:20 am

Oh and a observation to note. Thrust is considerabley higher from the intake ports than the exhaust.

PyroJoe
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Re: Odd Metal jars

Post by PyroJoe » Thu Jan 19, 2012 2:46 pm

The tail thrust should nearly double after the intake is augmented.

Thats a nice valve Nick sent. I have his propane jar in process with one variation, I have doubled the scale. This will some what test if I can scale it up. Hopefully with the larger size I can use the needle valves off a propane camp stove to run it without much fuss. Thanks to metizs information we have more details and a starting procedure.

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