Please put your "I am new and need help" question here.

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DrBwts
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Re: Please put your "I am new and need help" question here.

Post by DrBwts » Fri Sep 13, 2013 6:49 pm

Hi everyone,

So I'm thinking about making a valveless pulsejet to power a kinetic sculpture. Nothing too big & something ideally self starting or very easy to start anyways.

The jet will be mounted on arm-pivot to achieve circular motion...

Image

The lever arm will basically be a cam that drives the rest of the sculpture.

I have a mechanical engineering background but I specialize in biomechanics so my thermo-fluids is a little rusty :)

Anyhoo any advice &/or designs that you think will work would be most appriciated.

Thanks

Nic

Mark
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Re: Please put your "I am new and need help" question here.

Post by Mark » Sat Sep 21, 2013 1:39 am

I'm dwelling on making a simple kinetic art piece too with my "snorkelers". Not that jam jars with exhaust tubes make much thrust but they're enough for something small and delicate. One big advantage though is that small snorkelers aren't deafening. It gets tiring listening to a lot of noise very quickly and a pulse jet in and of itself doesn't fascinate you for very long. With your background you should be able to bang out a valveless pulse jet of some kind in no time. But it is fun to combine ideas, make something new.
Perhaps you can read past posts to get some idea of what might do best. I've not built any valveless pulse jets to speak of and only a handful of crude valved designs.
Another thing I thought would be fun is to design a jellyfish jet that poofs along cycling very slowly relighting itself every few seconds or so as it airs itself out. Platinum wire will reignite methanol in this fashion, just as it does in a little model airplane engine of course. Good luck with your project.
Here's some platinum catalyst I was playing with one day on a table and I accidentally lit/started a nearby jam jar that happened to have some leftover methanol in it. I was just misting the petri dish with methanol and the flame front started it up, thus I decided to do it intentionally here.
http://www.youtube.com/watch?v=gJuT5QtU54Q
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i like dots
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Re: Please put your "I am new and need help" question here.

Post by i like dots » Tue Feb 18, 2014 1:44 pm

Hey guys! im new here. Im a student in Tampa FL.

Ive built a valved 30 pounder from erics calculator, but im just waiting for the campus machine shop to finish cutting/rolling the metal (free, but slow!).
In the wait we built a half scale "ugly stick" from pipe-fittings, would have liked to go full scale but nobody had 2x3/4 reducers.

Its running, or idling or something I cant tell! No regulator on the tank, Its got a rosscojector, ive noticed this injector does not shoot gas straight down the tube, instead at a slight angle, it this right?
anyway, here is the video! https://www.youtube.com/watch?v=6E7SbZLwPNE

metiz
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Re: Please put your "I am new and need help" question here.

Post by metiz » Tue Feb 18, 2014 3:41 pm

It's pretty close. Make sure your injector in pointed straight down the intake and mess around with the position. Sounds like you'll need some more gas. Is your propane tank full? Is it icing up? put the tank in some warm water to get more preasure
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i like dots
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Re: Please put your "I am new and need help" question here.

Post by i like dots » Tue Feb 18, 2014 5:39 pm

Its a large full propane tank, so it's not icing up in the time I run it.

Its getting as much fuel as it can with the injector cut like it is, I will try to open the injector a hair so it can get more fuel. And I will try to have the jet of gas shooting straight down the intake inline with the injector.

cadet
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Re: Please put your "I am new and need help" question here.

Post by cadet » Fri Mar 14, 2014 4:42 pm

Hi everyone I have a few starter questions. Does the intake flare length count as part of the overall intake length? Also is there a rule of thumb for the size of the radius of the flare? Thank you.

Cadet.

DDuffin
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Re: Please put your "I am new and need help" question here.

Post by DDuffin » Wed Mar 26, 2014 6:35 pm

Hi Everyone

I recently built a Lockwood style engine and have been trying to get it to run ,But no luck. I am hoping someone on the forum can help guide me to the problem.

Ill overview what I have tried so far in my setup. The engine is made from 16 gage SS and combustion chamber,cones and tail pipe were folded on a break, The elbo’s and straight pipe sections are from standard SS tubing.

Fuel is injected through a SS Ferrell fitting located 30 mm forward of the big diameter edge of the inlet cone . Ignition was first tried by placing a small gasoline soaked rag into the C/C ,I then drilled a 1/16” hole near the discharge end of the C/C and introduced a flame with a propane torch . both methods seem to work OK but not sure of the effect of the small hole.

I have tried several nozzle types ranging from a straight 4 mm ID tube at various lengths to a 4 mm tube spanning the chamber and successively drilling 1/16” holes along its length starting with 4 holes and ending up with 8 holes.

I can get something that sounds like it is close to starting when introducing compressed air into the inlet but not much more than a hum that lasts a second or so after the air is stopped.

My fuel setup is a standard propane tank with the fitting and hose from a weed burner ( no regulator) .the tank fitting on the hose had a small plastic check valve built in and I removed it to increase flow.

The engine exhausts black smoke when it sounds closest to starting and the addition of more fuel diminishes the possible attempt to run.

After deciding that the engine would not run I decided to add a length to the tail pipe and added the 11” section shown in red in the attached drawing with no improvement to the function.

I have attached a drawing but im having problems attaching the photo.

What do you think?
Attachments
jet on bench.JPG
pulse model drawing.JPG
here is a photo and drawing

metiz
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Re: Please put your "I am new and need help" question here.

Post by metiz » Thu Mar 27, 2014 2:28 pm

Did you follow existing plans or did you design it yourself?
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Valveless Sam jet
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Jam jar jet

Post by Valveless Sam jet » Tue Jul 29, 2014 8:36 pm

If any of you have heard of the jam jar jet (tin can in this case) could I insert a probation injector into it and use propane as fuel? Many thanks, Sam. :D

jamjarjim
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Re: Please put your "I am new and need help" question here.

Post by jamjarjim » Mon Aug 11, 2014 1:21 pm

Hi folks, i'm Jim, I'm in th UK, just joined the forum, this is my first post :)
Valveless Sam jet wrote:If any of you have heard of the jam jar jet (tin can in this case) could I insert a probation injector into it and use propane as fuel? Many thanks, Sam. :D
Hi Valveless Sam jet, If you are refering to the Thermo Jam type apparatus posted on here by Ghrey, then yes ive been working on a copy of it myself, with good results :D Not sure what a probation injector is, but i would also like to use propane or butane as a fuel.

Have you built and tested anything yet Valveless Sam jet???

I have the same question to everyone else - has anyone else replicated Ghrey's work, and if so could you point us newbies in the right direction please!?!?!?

Regards, Jim

wolfchen75
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Re: Please put your "I am new and need help" question here.

Post by wolfchen75 » Sat Nov 08, 2014 10:19 pm

HI all, after moths of frustration trying to get a MEW 309 engine to fire, I purchased a Hobby King "red head" pulsejet. It's been very difficult to start on gasoline (the recommended fuel) , using a compressor for air source, it seems that fuel is running out the front of engine not being forced through the reed valves. I saw a video on the internet where a man modified the angle of the air pipe to blow the air up higher in chamber, but no answer as to what is the correct angle ,mine came from the shop at 35 degrees, how acute should it be ? what about a different fuel and another thought is to pressurize the fuel tank instead of blowing across the fuel port ? any suggestions ?

I have got it to fire but will not run without the compressor, so it's not developing the proper state


Jeffrey Vogel
Bridgehampton NY

Mark
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Re: Please put your "I am new and need help" question here.

Post by Mark » Sun Nov 09, 2014 3:05 am

I accidentally broke the blow pipe off of my Dynajet when trying to unscrew the part when the jet was still hot. So I took to just aiming an air compressor nozzle over the flowjector holes and it started that way. If you go with a different fuel like methanol those two holes have to be bigger than for gasoline. Try to aim the air so it is shared evenly over the two holes or centered between them I guess you would say. Also try short puffs of air instead of a steady blast. If you angle the air wrong, you can sometimes force the fuel back up the fuel line instead of aspirating it out like it's suppose to do. I think if you just wanted to start it and fix the problem later, you can try a few angles and see what comes about. Look to see if the fuel is wisping out when you hit the flowjector with air and try varying the angle. Good luck.

Here's a photo of my store boughts with the broken air pipe next to a Tigerjet and Bailey pulsejet which has 10 smaller holes instead of two. If you enlarge the photo, you can kind of see the angle and distance of how the other two designs are situated. This might not be of any great help but it's not rocket science, rather just something critical. Once you start a Dynajet a few times you start to get a feel for it or find what works and what doesn't.
download/file.php?id=7907
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Ryan Blake
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Re: Please put your "I am new and need help" question here.

Post by Ryan Blake » Mon Nov 24, 2014 3:55 am

Is there anywhere that I can get plans for the ThermalPulse 180 engines? I looked up everything I could on them - seems that Eric is now at pulsejetengines.com, but there doesn't seem to be any way to contact him anywhere. :( I have found a plan for the straight 12lb engine, but that is it. It is just that the TP 180 engines look easy to build and are apparently quite fuel efficient, :D if I am not mistaken.

nickwilson
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Re: Please put your "I am new and need help" question here.

Post by nickwilson » Mon Jan 05, 2015 5:31 am

looking for plans look here forum ryan

gerre
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Re: Please put your "I am new and need help" question here.

Post by gerre » Fri Jul 31, 2015 10:47 pm

Hey everyone,

I'm a student aeronautical engineering and I'm new here on this forum.

In the context of my thesis I'm looking for the exact working principle behind pulse jets.
I know that the Kadency effect forms the basics for a pulse jet to work, but during my research I also saw other effects like the Rijke effect
(turning heat into sound by creating a self-amplifying standing wave) and Helmholtz resonance (air resonance in a cavity) that look very
similar to the working proces of a pulse jet. For the moment I'm very confused. Are these effects in any way related to each other or to
the working principle behind a pulse jet?

Thanks in advance! :D

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