See through jet

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Jutte
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Re: See through jet

Post by Jutte » Thu Nov 27, 2008 10:54 pm

Just a suggestion Metiz re the water bath.Might be an idea to have the
top open and not sealed for the first try.That way by looking down on top of
it ( so to speak)..if there are any pressure peaks from the Pulse Jet body
flexing you won't spring a leak around the glass...and waste a lot of work etc.
If there's no problem then you can seal it the top with glass .
You might also be able to use a large well made fish tank. I saw a large fish tank used
once to test semiautomatic pistols and revolvers( .38, .45,.44mag ) for complete
submerged firing of said weapons. Lots of water went upwards but the handguns
and the fish tank surprisingly survived.
I can't remember if there was kevlar at the projectile end, but live rounds were used.
Just my 2 cents worth.

metiz
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Re: See through jet

Post by metiz » Fri Nov 28, 2008 4:21 pm

Right ordered a piece of 10 mm layerd safety glass. should be in by monday. see how that works out
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Ghrey
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Re: See through jet

Post by Ghrey » Sat Nov 29, 2008 8:24 am

Will an engine with that much cooling lock in and run?

The water jacket looks like a good idea to me, structurally speaking.
In the process of moving, from the glorified phone booth we had to the house we have.

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Re: See through jet

Post by Mike Everman » Sat Nov 29, 2008 3:36 pm

It'll run just fine with cooled walls. Our hero Paul Schmidt did it to see if the hot walls were necessary, and Eric Beck posted a video, I think called "pulsejet water heater", with a motor completely submerged and running bonkers.

I keep meaning to do a glass variant, because a friend of mine has access to an InGAs thermal camera. If I'm not mistaken, it'll do 1,600 fps, but I know not if it will see through glass. I keep meaning to ask him. He's a funny cat, "Dr. Megavolt" is his handle. he's big-time at Burning Man, shooting huge lighning bolts from gigantic Tesla coils.
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metiz
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Re: See through jet

Post by metiz » Sat Nov 29, 2008 4:37 pm

Mike Everman wrote: If I'm not mistaken, it'll do 1,600 fps
1600 fps....

Why are you typing this! go borrow that sucker!
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Re: See through jet

Post by Ghrey » Sun Nov 30, 2008 7:27 am

Yah ... Not oh 20 minutes later I had one of those " I posted what stupid question ??? " moments.


Of corse it will run.


The only posable question ( irrelevant in this case ) would be throttle range. And there is no small room for debate in that area,,,,


.:.

Note to self: MUST find a bigger toy, oh um equipment, yah, equipment budget.

.:.
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metiz
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Re: See through jet

Post by metiz » Mon Dec 01, 2008 1:54 pm

10mm layerd glass get!

This will at least take the grunt of the machine gunning. If this glass also breaks, ill go with heat resistant glass incased in water.
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Re: See through jet - high speed cheating

Post by metiz » Wed Dec 03, 2008 4:38 pm

ok so I now got a pane of glass 10 mm thick and hopefully i will be testing the engine again next saturday. I still don't have a highspeed camera though so I was thinking this:

My camera shoots at 30 or so frames per second (fps) after some tweaking I found out that the shutter speed can be adjusted to 1/10.000 of a second. this means that, even though one frame will catch like 10 cycles, if the timing is right (and there are 30 opportunities per second for that) one frame will be able to catch the gasses at a certain interval, say midway a cycle. It should be possible to string a couple of seperate frames together from the raw video and paste them together in sequence to get one or more frame by frame cycles of the engine.

What are your thoughts on this. Is it possible or am I missing something?
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Re: See through jet

Post by Mike Everman » Wed Dec 03, 2008 5:56 pm

I've always thought that you could do that. It'll be a fun project trying to paste together representative snapshots. You may end up influencing what you do with what you expect to see, though, but doubt it can be screwed up too much. cool
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larry cottrill
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Re: See through jet - high speed cheating

Post by larry cottrill » Wed Dec 03, 2008 6:05 pm

metiz wrote:My camera shoots at 30 or so frames per second (fps) after some tweaking I found out that the shutter speed can be adjusted to 1/10.000 of a second. this means that, even though one frame will catch like 10 cycles, if the timing is right (and there are 30 opportunities per second for that) one frame will be able to catch the gasses at a certain interval, say midway a cycle. It should be possible to string a couple of seperate frames together from the raw video and paste them together in sequence to get one or more frame by frame cycles of the engine.

What are your thoughts on this. Is it possible or am I missing something?
This would work well if the frame rate comes somewhere close to (but not exactly matching) the time of a group of cycles, and if the engine power development per cycle is highly consistent. Bruno Ogorelec has pointed out that both the cycle time and the explosive power in each cycle varies a lot more than we think from our (usually) casual observations. This doesn't mean you shouldn't try it, of course, but you may have a lot of trouble achieving a sequence of frames with good "smoothness" of progression of the flame, i.e. the best you can do MIGHT turn out both "jerky" and "flickery".

Of course, there is also the distinct possibility that fortune will smile and the engine will run with unheard-of consistency, yielding sensibly perfect results. Ha. I say, go for it. It will certainly make an interesting editing project, in any case. Even at worst, it will probably be far more interesting than yet another imaginative graphic pulsejet animation.

L Cottrill

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Re: See through jet

Post by Graham C. Williams » Fri Dec 05, 2008 11:55 am

Casio ExLim. High speed movie recording at up to 1200 fps

http://exilim.casio.com/browse_cameras/ ... lim/EX-F1/

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Re: See through jet

Post by James D » Fri Dec 05, 2008 3:41 pm

I've got a Casio EX-F1, it's pretty good. It has limitations of course, especially regarding resolution but there aren't many 1200 fps cameras that are so small and easy to use.
http://www.exilim.co.uk/exf1/


I recorded some high speed video of an FWE with a glass end plate on the combustion chamber a couple of weeks ago, I'll post it in a new thread sometime.


Metiz, this is a great project, I can't wait to see your next video it's gonna be awesome.


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metiz
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Re: See through jet

Post by metiz » Sat Dec 06, 2008 4:34 pm

Thicker glass this time. Held up long enough for a decent test but this time the filler material was to blame, it didn't grip the glass tightly enough so it vibrated a bit with the pressure pulses. because of this, leaks also started to form. next up: submersion in water

http://www.youtube.com/watch?v=9fkEqNO-lMs

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Re: See through jet

Post by Mark » Sun Dec 07, 2008 4:45 pm

The glass held up much better than I was expecting. I'd hate to see you out there in the cold, but a night or twilight viewing would probably bring out the flames more.
I've lit some long pyrex and quartz tubes with methanol in them, it's neat the way the flame front travels in different directions, kind of like watching a long flickering fluorescent bulb really, the to-and-fro movement of the ionized gases, like more than one motion going on at a time, pressure waves traveling through each other.
Last edited by Mark on Sun Dec 07, 2008 4:56 pm, edited 1 time in total.
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Re: See through jet

Post by Viv » Sun Dec 07, 2008 4:56 pm

Superb! I think this has some legs on it but as you say the sealant is still a problem, do you have a alternative ignition you can try? personally I am not so fond of sparklers as opposed to an intermittent spark.

Well done all the same and keep developing your engine its a joy to see it running

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