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Author Topic: Rubens' Tube - waves of fire - Garage Science  (Read 27173 times)

Offline thedoc

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Rubens' Tube - waves of fire - Garage Science
« on: 22/04/2014 16:16:31 »
One of the most beautiful and impressive physics demos is Rubens' tube, producing waves of fire that dance to the sound coming from a loudspeaker.

 Read more about this experiment.


Garage science is a blog of science experiments you probably can't or shouldn't do at home


 
« Last Edit: 22/04/2014 16:16:31 by _system »


 

Offline Bored chemist

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Rubens' Tube - waves of fire - Garage Science
« Reply #1 on: 21/04/2010 19:12:33 »
Are you CORGI registered?
 

Offline daveshorts

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Rubens' Tube - waves of fire - Garage Science
« Reply #2 on: 21/04/2010 19:15:29 »
The way the flames were escaping from the end of my small test tube indicates not... I really need to work out some way of soldering/welding the end pieces on to make a good seal.
 

Offline Geezer

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Rubens' Tube - waves of fire - Garage Science
« Reply #3 on: 22/04/2010 07:41:24 »
Dump the aluminium and use copper instead. You'll have no problem soldering it.

It's just as well I did not know about this in the sixties. If I had, I'm sure I would have made one to put in the Disco.

On second thoughts, you might not want to do too good a job sealing the ends. If you happen to create a combustible mixture inside the tube, it would be good to have a sort of safety valve.

BTW, what's CORGI. What does Her Majesty have to do with this?
 

Offline rosy

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Rubens' Tube - waves of fire - Garage Science
« Reply #4 on: 22/04/2010 10:31:34 »
They register people trained to do gas installations. I think it stands for something-or-other of registered gas installers, but I'm not sure about that.

http://www.trustcorgi.com/Pages/default.aspx
 

Offline daveshorts

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Rubens' Tube - waves of fire - Garage Science
« Reply #5 on: 22/04/2010 11:59:50 »

It could certainly be a combustible mixture in the tube, but the holes act like a Davey lamp  
http://en.wikipedia.org/wiki/Davy_lamp
The metal conducts the heat out of a flame fast enough that it cannot propagate through the hole.

I would rather avoid copper, as it is expensive, heavy and easily damaged. I think soldering aluminium isn't as bad as all that, I just need to get a powerful gas torch
 

Offline Geezer

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Rubens' Tube - waves of fire - Garage Science
« Reply #6 on: 22/04/2010 18:00:06 »

It could certainly be a combustible mixture in the tube, but the holes act like a Davey lamp  
http://en.wikipedia.org/wiki/Davy_lamp
The metal conducts the heat out of a flame fast enough that it cannot propagate through the hole.

I would rather avoid copper, as it is expensive, heavy and easily damaged. I think soldering aluminium isn't as bad as all that, I just need to get a powerful gas torch

If you've never tried soldering Aluminium before, you're in for some fun. (It's a pain in the neck!) Here's a link that might be helpful.

http://chestofbooks.com/home-improvement/workshop/Handy-Man/How-To-Solder-Aluminium.html

Ah yes. I understand the Davey Lamp principle, but then again, Davey didn't have a honking big loudspeaker in his lamp either ;D. A safety valve would be good insurance.

My brother had a Hillman Imp. One damp morning it would not start. My brother is not among the most technically aware, so he kept on cranking the starter in the hope that, by some miracle, the fuel would ignite.

Evidently there was no problem with the carburettor because it did exactly what it was supposed to do and mixed the fuel and air in ideal proportions for combustion. Unfortunately this mixture was being pumped out of the engine and into the exhaust system in a sufficient quantity to completely fill the silencer.

Eventually, my brother got the result he desired. Ignition! There was an extremely loud bang and the silencer was split wide open from end to end. The silencer was also immediately de-coked and all the carbon deposits spewed forth as flaming embers in the explosion.

Fortunately no one was injured, but it certainly woke my brother up. I think he had to have a change of trousers.

« Last Edit: 23/04/2010 05:49:48 by Geezer »
 

Offline Geezer

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Rubens' Tube - waves of fire - Garage Science
« Reply #7 on: 22/04/2010 18:08:38 »
They register people trained to do gas installations. I think it stands for something-or-other of registered gas installers, but I'm not sure about that.

http://www.trustcorgi.com/Pages/default.aspx

Thanks! I see they even tell you "How to Spot a Cowboy". I'll try that out around here.

Well, I'm glad they are finally using trained corgis as gas fitters in the UK. I'm sure they'll do a much better job than some of the twits that used to work for our local Gas Board  :D
(OK! OK! - it was a joke - well, kind of anyway.)

EDIT: Come to think of it, our Gas Board really was a joke!
« Last Edit: 22/04/2010 21:36:29 by Geezer »
 

Jake

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« Reply #8 on: 04/06/2010 22:40:16 »
I am in the process of making a rubens tube for my physics class and having some difficulty.  After lighting the tube I will only recieve a small blue flame instead of a larger orange flame.  Also it won;t stay lit.  It will go out almost immediately after lighting.  Any help or suggestions would be much appreciated.
 

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« Reply #9 on: 10/06/2010 11:40:52 »
What would the optimum diameter for the tube be ? As this could cause a problem if copper were to be used and what distance did you put between your holes ? Thanks
 

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« Reply #10 on: 14/06/2010 04:41:01 »
Aluminum is a pain make your job easier and just use JB weld. It'll hold at about 500 degrees, it's permanent, and a 100 times easier than working aluminum.
 

Offline daveshorts

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Rubens' Tube - waves of fire - Garage Science
« Reply #11 on: 21/06/2010 09:15:00 »
I am in the process of making a rubens tube for my physics class and having some difficulty.  After lighting the tube I will only recieve a small blue flame instead of a larger orange flame.  Also it won;t stay lit.  It will go out almost immediately after lighting.  Any help or suggestions would be much appreciated.
Sounds like you are not waiting for long enough, or just don't have enough gas flow, so the flames are very oxygenated. I don't know what kind of gas you are using, methane would probably burn cleaner than propane anyway.
 

Offline daveshorts

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Rubens' Tube - waves of fire - Garage Science
« Reply #12 on: 21/06/2010 09:17:55 »
What would the optimum diameter for the tube be ? As this could cause a problem if copper were to be used and what distance did you put between your holes ? Thanks
I used 1mm holes at a 5mm spacing. I am not sure of optimum diameter. I think for a 1800mm tube like mine more the 50mm diameter is great for higher order modes, but the fundamental doesn't work quite so well. I also had a test tube which was only 20cm long which would only do fundamental and first harmonic, I think because the cross section was larger than the second harmonic, so complicated 3D standing waves started happening.
 

Offline jgoldbeck

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Rubens' Tube - waves of fire - Garage Science
« Reply #13 on: 04/05/2011 09:08:06 »
I used 1mm holes at a 5mm spacing. I am not sure of optimum diameter. I think for a 1800mm tube like mine more the 50mm diameter is great for higher order modes, but the fundamental doesn't work quite so well. I also had a test tube which was only 20cm long which would only do fundamental and first harmonic, I think because the cross section was larger than the second harmonic, so complicated 3D standing waves started happening.

Great post!  I've been working with Ruben's tubes for a few years now and have come to the same conclusion you have about the loud volume behavior.

I was wondering if you could expound a little more on the effects of different diameter tubes.  We're working to make a fully optimized tube.  :-)  More details after we've got it up and running.

Also, I second the JB-weld.
« Last Edit: 04/05/2011 09:28:26 by jgoldbeck »
 

Offline daveshorts

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Rubens' Tube - waves of fire - Garage Science
« Reply #14 on: 04/05/2011 09:48:36 »
To be honest I haven't done a lot of development work after getting it to work. I have a feeling making the tube slightly larger than 50mm for the 1.8m I used would be a good idea.

My feeling is that if the tube is too narrow, the low frequency resonances will be weakened (I definitely see this) but as the tube gets wide, the high frequencies will start to have a wavelength similar to the radius of the tube, and I imagine that you will get all sorts of exciting modes of vibration across as well as along the tube. I think this will tend to smear the resonances, which is what I see with mine. It works beautifully for short wavelengths but you don't really get the first couple of modes.
 

Offline Airthumbs

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Rubens' Tube - waves of fire - Garage Science
« Reply #15 on: 04/05/2011 16:01:44 »
Does anyone have a practical use for this device? Apart from being used as a physics demo. I saw it on Garage Science (Did not look like a kitchen  [8D]) and it looks pretty cool but...... whats it for?  There must be some practical uses?
« Last Edit: 04/05/2011 16:03:22 by Airthumbs »
 

Offline jgoldbeck

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Rubens' Tube - waves of fire - Garage Science
« Reply #16 on: 05/05/2011 09:09:44 »
Yeah, play your instrument of choice through it for a ridiculous live show  :D
 

Offline levo1969

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Rubens' Tube - waves of fire - Garage Science
« Reply #17 on: 20/05/2011 10:37:51 »
Hi
I made one of these using 50mm PVC pipe and it worked well.
I then attempted one using 50mm galvanised pipe so it would last longer and it doesn't work.
Any thoughts on what may be wrong?
The holes in each are 2mm diameter and spaced 10mm apart.
each tube is about 180cm long.
regards
levo1969
 

Offline Jlfonz

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Rubens' Tube - waves of fire - Garage Science
« Reply #18 on: 05/06/2011 21:32:17 »
I haven't tried building one of these but may have an idea to help.  Has anyone tried to bevel the holes similar to an orifice in any consumer gas appliance?  If I remember correctly it greatly effects the organization of the flow of gas molecules passing through. There are calculators available online to determine size and desired effects.  Maybe finely tuning the tube will accentuate the effect.
 

Offline Jlfonz

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Rubens' Tube - waves of fire - Garage Science
« Reply #19 on: 05/06/2011 22:04:46 »
More thoughts about this.  What is at the opposite end of the speaker?  If it is some sort of rounded end cap it will severely distort any reflected sound waves in such a small area.  Would putting a sound deadening material in the opposite end eliminate any standing waves. Something like loose fiberglass or foam.  How about a completly flat surface on the opposite end that can either move with the sounds waves or be adjusted for distance from the source?  How about an identical speaker on the other end pointed in the same direction as the source speaker.  I think this might create a graphic equaizer effect of the flames.  It seems that this is the overall desired effect.  I also believe that some of you may be dealing with pressure issues.  If your fuel source does not give enough volume and pressure you would need smaller orifices (orifici?) to maintain a flame.  If they are to big for the source they will not burn well as the oxygen mix would be way to high.  If using propane tanks for gas grills---try using two of them.  This would also help to alleviate the issue stated in the original post--of oxygen being sucked into the orifices (orifici?) at the troughs. BTW--even if I am wrong--this is fun.
 

Offline rationalmaximiser2

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Rubens' Tube - waves of fire - Garage Science
« Reply #20 on: 04/07/2011 13:53:29 »
Hi guys. As my first post I'd like to tell you about my Rubens Tube.

Materials
=========
1 1.9m 75mm gorrigated iron down pipe (Bunnings, $10)
1 1.9m 220x15mm pine
2 0.3m 220x15mm pine
1 jaycar 100mm speaker
  silicon rubber
1 200x200x7mm plastic plate (hole in middle for blowtorch thread)
1 blowtorch
1 set of $5 computer speakers (for the amp)
1 iphone with oscillator app

Design
======
65 2mm holes in the top, 20mm spacing.
Cut two big holes in the small bits of pine to house the pipe, attach on top of either end of the base. seal pipe flush to the end of the wood with silicon rubber. On one end, mount the speaker (silicon seal), on the other, the blowtorch/plate.

I've been able to demonstrate a standing wave at various frequencies, and use it as a great visualiser for music (youtube video on the way)

This is just something i knocked up as a pilot - I'm designing mach 2 now. Any suggestions? One thing I'll do is reduce the jet size, and spacing. Jets currently have difficulty lighting their adjacent flame.

By the way I'm not a pyhsics teacher, just an independent learner. I wonder if any schools would like to borrow the tube? I'd be happy to lend or demo.
 

Offline imatfaal

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Rubens' Tube - waves of fire - Garage Science
« Reply #21 on: 04/07/2011 15:34:36 »
Very cool - in fact from the look of those flames, very hot as well.  Look forward to the videos - but remember to hold safety first!
 

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Rubens' Tube - waves of fire - Garage Science
« Reply #21 on: 04/07/2011 15:34:36 »

 

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