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Author Topic: Replica of Palma's homopolar generator  (Read 8770 times)

sigis

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Replica of Palma's homopolar generator
« on: March 07, 2010, 10:47:59 PM »
There is Replica of homopolar generator. Still not working, problems with leaking of mercury. Also mercury is very poison. Now we will try Indium alloy. Biggest problem is to avoid leaking with very high rotation like 25000 rpm. Appreciate for advices how to solve this problem. 
« Last Edit: March 08, 2010, 01:51:33 AM by sigis »

petersone

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Re: Replica of Palma's homopolar generator
« Reply #1 on: March 07, 2010, 11:08:57 PM »
Hi Sigis
Beautiful build,if it runs like it looks it will be something special.Hope you get it going soon.
peter

DreamThinkBuild

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Re: Replica of Palma's homopolar generator
« Reply #2 on: March 08, 2010, 12:38:04 AM »
Welcome to the forum Sigis,

Impressive build and machining. Hopefully the mercury leak will only be a very short setback. Are the copper blocks all one piece?

sigis

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Re: Replica of Palma's homopolar generator
« Reply #3 on: March 08, 2010, 01:43:25 AM »
There is two peaces of coper up and down, like in Palma's machine.
Problem with mercury leaking, that is very difficult make small gaps between rotor and teflon separators.

mikestocks2006

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Re: Replica of Palma's homopolar generator
« Reply #4 on: March 09, 2010, 07:43:53 PM »
There is two peaces of coper up and down, like in Palma's machine.
Problem with mercury leaking, that is very difficult make small gaps between rotor and teflon separators.
Hi sigis,
Can you provide few more specifics about leakage, and where exactly does it occur and when? Maybe a blowup schematic of the areas in question could be of more help to better identify the problem and possible solutions?
You only need enough conductive liquid to bridge the gap between the outer edge of your copper rotor and the facing area of the corresponding pickup stator. Making the gap small enough but not too small (account for surface tension, wetting and laminar vs turbulent dynamic states of the conductive liquid, rotational speed related, ofc and thermal expansions etc) would be helpfull.
It maybe easier to pour in the liquid slowly as the rotor is already in motion and slowly speeds up to avoid cavitations, air bubbles, slowly achieve a continuous film/body of fluid in the gap. You may also want to include a drain port at the bottom to start removing it as the rotor slows down and gravity starts taking over causing the liquid to gather at the lower area and overflowing from the sides.

Agreed with posters above on mercury, and as already noted possibly a Eutectic Alloy of Ga-In,  24.5%In might be better for safety and overall handling, it’s liquid above 15-16 deg C

Do you have any vibration issues (liquid conductor present) and if yes at what speeds?

I hope this helps
Mike

sigis

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Re: Replica of Palma's homopolar generator
« Reply #5 on: March 10, 2010, 01:02:14 AM »
Hi Mike,
Thanks for your answer. There is problem, that by high speeds( over 10000rpm) of rotation, rotor has little bit vibration, but no resonans on some speed. If we making to small gaps, separators stops motor (1,5kw power). That we need to make gaps equal to vibration amplitude. But true those gaps mercury leaking very ease. With indium alloy more problems, because this alloy is like water. Now we looking for special separators with some elastic parts, to allow little vibration of rotor. Also looking for some experience for high speed turbines construction in power plants, they have the same problems. But still not find draw of such turbine. I attach some draw of machine to be more clear.
Sigitas. 

leo48

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Re: Replica of Palma's homopolar generator
« Reply #6 on: March 10, 2010, 11:33:04 AM »
Congratulations for the work done to resolve the loss of liquid mercury see if you can apply these seals
http://www.hdslippers.it/
regards
leo48

Paul-R

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Re: Replica of Palma's homopolar generator
« Reply #7 on: March 10, 2010, 05:24:42 PM »
There is Replica of homopolar generator. Still not working, problems with leaking of mercury. Also mercury is very poison. Now we will try Indium alloy. Biggest problem is to avoid leaking with very high rotation like 25,000 rpm...
This thing will need to be balanced; and dynamically balanced at that.

You should not allow anything of value to be in the plane of rotation.

mikestocks2006

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Re: Replica of Palma's homopolar generator
« Reply #8 on: March 10, 2010, 09:28:35 PM »
Hi Mike,
Thanks for your answer. There is problem, that by high speeds( over 10000rpm) of rotation, rotor has little bit vibration, but no resonans on some speed. If we making to small gaps, separators stops motor (1,5kw power). That we need to make gaps equal to vibration amplitude. But true those gaps A leaking very ease. With indium alloy more problems, because this alloy is like water. Now we looking for special separators with some elastic parts, to allow little vibration of rotor. Also looking for some experience for high speed turbines construction in power plants, they have the same problems. But still not find draw of such turbine. I attach some draw of machine to be more clear.
Sigitas.

Hi sigis,

First, on the leakage issue:
as far as the gap goes, a better more accurate machining/grinding maybe required to closer tolerances for just a fine clearance fit of the parts, but that can get expensive.
You may want try high surface speed rotary seals, some can go as high as 40 m/s
As an example
http://www.ahpseals.com/products/high_perf.php up to 40 m/s
http://www.systemseals.com/rotary-seals.htm  up to 35m/s
Per your drawing, your sealing circular area is of no more than 70 mm dia (actually a bit less) and at 10k rpm you are looking no more than 36.65 m/s surface speed.
 In addition, if you can get your expected effect at lower speeds by using stronger magnets (if you haven’t maxed out what’s available) it may even be better for friction, sealing effectiveness and duration.
If you are looking at much higher speeds you are possibly looking at non contact surfaces vane pumping action designs and it will probably get cost prohibitive and it may also negatively effect the conductive fluid.

Second, on the vibration issue:
why do you have to get to 10K rpm? If this is a direct duplicate of the DePlama machine, according to their tests and calculations they need to cross just above 6K rpm to get overunity, the power out is increased by the square (2nd power) of the speed (rotational) vs composite friction and other losses that are increasing by the 1.5 power of the speed.
They also had a vibration issue.
See also this thread and videos # 9 and above and especially #11
http://www.overunity.com/index.php?topic=626.new#new


I hope this helps
Mike