Naked Science Forum
On the Lighter Side => New Theories => Topic started by: fgt55 on 24/03/2012 13:54:02
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Hi,
My son are looking for systems on internet for give energy free, I know it's impossible and until now I arrive to say where is the problem but I don't find for this one ? Can I expose the system ? It's not very complicated for explain, it's only 2 wood screws and differents pressures.
Regards
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Hello,
You'll have to explain a bit better what the system you are discussing, and where energy is involved.
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Ok, thanks
The system is composed with 2 wood screws (helicoids). Each screw can only turn around its longitudinal axis (translation is not possible). Screws are put closed, the thread overlap other thread. All the system is under pressure P except one screw has around itself 3P and small volumes has pressure 2P. (Small volume=interface) Small volumes are where threads overlap. Screws turn at the same rotational speed in the same direction. All volumes are constant. I tested with 2 real wood screws, effectively screws turn, I see interface move up but like the interface is composed with 2 surfaces from threads and 2 gaskets's surfaces which are in the longitudinal axis, I see nothing lost energy.
First drawing: the principle, but green area can be very small like second drawing show. Third drawing show the volume of the interface composed with 2 parts of screw and 2 gaskets.
this for find the problem easily:
1/ Screws turn at the same speed in the same direction, so they don't move up/down, it's mechanical
2/ The interface with 2P pressure put a difference of pressure which want to turn screws in the same direction. My son see screws giving energy and me too !
3/ Interface has always the volume constant.
4/ Interface is moving in translation only in the longitudinal axis
5/ Interface is composed with 2 surfaces of helicoids and 2 surfaces of gaskets. Gaskets's surfaces are are parallel to longitudinal (or can be) so zero energy is needed for move in longitudinal axis the interface.
6/ All system can be put under P pressure like that red helicoid don't need something for retain pressure.
7/ Black helicoid is under pressure 3P, this pressure can be retain by a very thin film of pressure (with a hard material and gaskets for retain pressure). The hard material is moving when the interface is coming. Like the film can be very small, this need to take off very small pressure. The volume of the black helicoid with 3P pressure is constant because the interface is moving (need to take off and need to put 3P pressure). This need zero energy in theory for me.
Sure this system need gaskets, a lot ! and a special screw for retain 3P pressure. The film of pressure can be very thin, the side must move in real time with the moving of interfaces, difficult to do in practise but in theory this can't give more energy than received !!
I need help for explain where is the problem I don't see it :)
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A mechanism like a lever or a screw can multiply force (https://en.wikipedia.org/wiki/Force) (pressure),
but does not multiply energy (https://en.wikipedia.org/wiki/Energy). Energy cannot be created or destroyed (https://en.wikipedia.org/wiki/Conservation_of_energy).
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I'm sure, you're right but I don't find where is exactly the problem can you explain ?
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Obviously with gaskets, you get friction.
But, that aside, in a system with a pressure differential, you tend to get movement in a direction that relieves the pressure differential. If motion doesn't relieve the pressure differential, then it would be unlikely to turn.
So, ignoring friction, the pressure would tend to try to drive the 3P screw out of whatever is holding it. And, it would also tend to drive the 1P screw further into it. If it is designed so that the screws don't actually move, then the turning the screws won't actually relieve pressure, and there would be nothing to drive the movement forward.
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Yes, I'm ignoring friction.
If the screw move with longitudinal axis, screw can only turn, the axis can block the longitudinal translation I think (with bearing). Rotation is only the liberty for screw I don't know how one screw can go to another ?
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What you have is esentially a nut and bolt.
You can multiply the force at the expense of motion, but, because of friction, you are unlikely to multiply the motion at the expense of force.
The reason nuts do not unscrew themselves is because of friction between the nut and the bolt, although, when there is vibration, or repeated heating and cooling, a nut can creep on a bolt and lose tension.
Friction is heat energy, so if there is any friction at all (and there always is) you will get less work (mechanical energy) out than you put in.
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What you have is esentially a nut and bolt.
Not really.
Have you read all my first message ? Have you understand all the message, if not don't hesitate to ask.
We can limit all friction but not to zero sure ! But friction can't cancel all the energy give by rotation unless you want it. Screws can't move in translation, so the interface can move up easily, gaskets and friction is only here because there is a difference of pressure.
A torque exist and rotate screws. The another thing to move is interface: 2 longitudinal surfaces, how the energy is lost ? I need an explanation for explain.
You're right friction is energy, so if screws give energy, if friction is energy where the energy is lost ? Do you think all energy give from screws are transform in heat ? Why, explain please.
is because of friction between the nut and the bolt
it's 2 wood screws like drawing show, so they can turn togeter easily.
Please read the first message
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Hi,
I take time again to thinking about this problem and I don't know where friction is, if you could explain ? because when I take 2 wood screws in my hands they turn freely IF rotational speeds are the same.
For the interface, gaskets's surfaces can be hard surfaces except at junction where it's possible to use something like radial shaft seal technology for example, so the friction can be reduce I think. If not, can you explain please ?
Regards
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Are you rotating both screws at the same time?
If you are, there never needs to be any contact between the screws so there is no force transmitted between them. If there is no force, there will be no friction.
You can get the same effect by rotating two meshed gears so that the teeth never actually make contact. Or you can put a nut on a bolt and rotate the bolt and allow the nut to rotate with the bolt.
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Yes, I'm rotating both screws at the same time. There is always a line in contact (I used wood screw), see the drawing. One screw never block other, sure the speed must be exaclty the same. A line is not a surface but the volume of the interface is something like the yellow part in last drawing: 2 surfaces from helicoids and 2 hard surfaces which is the really the interface, these surfaces are curve but in longitudinal axis. Maybe if you have 2 wood screws this can help me to understand.
Thanks for your help
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I add a drawing for show the real volume of interface. It's the other side of the last drawing. One screw is under P, other under 3P and interface under 2P.
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I really don't understand what the question is.
The two screws rotate and don't interfere with each other. A lot of things (like bearings for example) can have relative rotation without interfering each other. This isn't really any different.
Are you thinking this mechanism could be part of a pump or something?
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Sorry. It's not a pump, all volumes are constant and pressure P, 2P, 3P never change. Red screw has around it P, black screw has around it 3P, the interface has inside 2P. Black screw see a differential pressure 3P/2P on a small part of a surface, this rotate with torque the black screw. Red screw see a differential 2P/P on a small part of a surface, this rotate (in the same direction than black screw) with torque the red screw. Interface move in longitudinal axis only but like surfaces are in longitudinal axis this don't need energy (2 surfaces of the interface is screws but screws don't move in longitudinal axis, but they turn). So if the friction for contain pressure can be small, where the energy is lost ?
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What you have is a type of helical gear.
http://en.wikipedia.org/wiki/Gear#Helical (http://en.wikipedia.org/wiki/Gear#Helical)
However, the slope of the helix with two screws is so small that the mechanism will tend to wedge as soon as you use it to transmit torque from one screw to the other. If the screws had much steeper slopes, and you had multiple helixs on each screw, you would have two helical gears meshed, and you would be able to transmit torque.
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It's not one screw which transmit torque to another. It's the difference of pressure which create 2 torques, one for red screw and one for black screw. Screws are independant (but controlled for have same rotational speed). The slope is the slope of the pitch of the screw is not so small.
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Yes, but you still have a helical gear : )
OK - I give up.
If both of the screws are being driven at the same speed, what does it matter whether the helixs contact each other or not, and what is the purpose of this machine?
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My son has seen that idea on internet, I don't know where. The purpose is to give more energy than the system receive...I know it's not possible and often I find where is the problem on several systems. But here no ! Here I think the idea is to put 3 fixed pressures, 2 screws, gaskets, controlled system, etc. and recover energy from rotation of helixs (for me the translation of interface don't need energy), the rest of the system don't lost energy. I hope you don't give up ;)
We can imagine sensors with controlled system which driven at the same speed screws, it's only a technical problem (at least for me). The contact of helixs is not essential, it's the volume of interface which must be constant (for not loss energy I think). The volume of interface give a surface for each helix, the differential's pressure rotate screws and torque.
The volume of interface is not 0, see yellow part in reply #2
Maybe if you read the reply #2 you can find where an hypothesis is false ?
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You need to draw a box around the system and identify all the energy inputs and all the energy outputs. Total input must equal total output. If they are not equal you are overlooking something.
I can assure you that what you have is a variation of a helical gear, and there isn't a gearing system that is even 100% efficient let alone more than 100% efficient. I encourage you to study how gears work, and where they lose energy.
I'll be moving this topic to the "New Theories" forum in a little while.
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Ok, thanks
Something important: 2 screws are motors, it's not one motor and one receptor, each give motor's torque.
I think 2 screws can be really independant, I don't see them like a gear when a screw will turn other, and maybe it's the problem. But I'm thinking about your message.
For now, maybe my misunderstood is I think the screw turn where there is a difference of pressure on a small part of surface (only one side), see drawing. Here there is ONLY one screw. One screw turn like that and give a torque ? Sure like that the sum of energy is 0 because I need to adjust the position of the red point.
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I think I understood your point of view, maybe you think one screw turn and give torque to the second screw ? Two Screws turns independantly and give a torque for turn 2 receptors. If you see 2 screws like motors, one screw don't give energy to other. Tell me if it's that ?
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Are you trying to make something like this?
http://en.wikipedia.org/wiki/Rotary_screw_compressor#Superchargers (http://en.wikipedia.org/wiki/Rotary_screw_compressor#Superchargers)
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It's not exatly that, more complicated and it's the contrary: pressure => torque
Please, take the reply #20, for you the screw turn and give torque ?
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I still not sure I understand what it's supposed to do - probably a language thing.
Are you saying that fluid pressure contained by the green line will make the screws turn?
If that's it, the screws will not turn because no work is being done to make them turn. That would only happen if the volume of the 3P zone changed. The geometry of the screws ensures that the volume never changes.
If you contain high pressure gas in a cylinder with a piston, it only does work when the volume increases as the piston moves. If you look at the picture of the screw compressor I posted you can see that the helices have opposite screw directions so that work can be done on them to compress a gas. If the screws had the same direction they would rotate, but they would not compress anything.
Hope that's it!
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Are you saying that fluid pressure contained by the green line will make the screws turn?
No, I'm not saying that.
I would like to know if for you the unique thread on reply #20 (drawing) turn and give torque ?
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Are you saying that fluid pressure contained by the green line will make the screws turn?
No, I'm not saying that.
I would like to know if for you the unique thread on reply #20 (drawing) turn and give torque ?
Do you mean #21?
The answer is, generally, no. If it was yes, screws would be not be of any use because they would fall out all the time.
If you eliminate the rotational friction, and the friction between the point of contact and the thread, the screw will rotate. If you use a screw with a much greater pitch it will rotate much more easily.
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it's really the reply #20, but forget this reply I reformulate: for find my error I'm going step by step: I'm thinking with only one screw, 2 bars everywhere except at small red surface (only one side) where pressure is 1 bar. The screw can only turn not move in translation. Like this the screw turn and give a torque ? In this case, for me, the sum of energy is 0 because we need to move the small red surface in the same time. Are you agree with that ?
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The algebraic sum of the energies is always zero, but if some of the work energy produces friction, heat energy will be created and the work energy output will be less than the work energy input.
If there was no frcition at all in the system you could get as much work out as you put in, but no more. If there is any friction in the system (and there always is) the system converts work into heat and the system is less than 100% efficient.
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ok, the screw turn and give torque, the sum of energy is 0 and there is friction.
Second step: now, imagine you have 2 screws:
1/ one in your left hand where outside there is 1 bar except at small red surface where pressure is 2 bars (red surface at down), this screw turn and give torque, the sum of energy is 0 and there is friction. The screw turn in a direction.
2/ one in your right hand where outside there is 3 bars except at small red surface where pressure is 2 bars (red surface at up), this screw turn and give torque, the sum of energy is 0 and there is friction. The screw turn in the same direction than other screw.
Now, move closed 2 screws for put small red surfaces in front of (one is down, other up). The first drawing show a lot of volume where pressure is 2 bars but we can have only one. The volume where pressure is 2 bars is composed by 2 parts of screws down and up and 2 longitudinals surfaces (gaskets). For me, screws turn and give torque, there is friction (no more before) but for the energy the volume where there are 2 small red surfaces don't lost energy (for me) because 2 surfaces are longitudinal axis (gaskets) and 2 surfaces (red surfaces) are screws and screws don't move in translation they turn only. The small volume where pressure is 2 bars move in the longitudinal axis. The volume where pressure is 2 bars is constant. With one screw, the screw give energy and we lost the same energy by move the red surface. Here, we don't lost energy by move red surface because it's the other screw that diseapear the other side of the red surface. Finally, we have the system like first drawing show.
Sure there are 3 pressures, but for one screw we can say everwhere outside the system there is 1 bar, for the red volume (interface) the gaskets can controlled pressure. For other screw, the pressure can be controlled by thin film of pressure and thin film of dynamic wall, this need system for controlled walls but in theory this don't need energy (if friction is not 0 we lost energy but why 100% of energy we received from screws ?). See second drawing for that, it's a part of black screw for see details.
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ok, the screw turn and give torque, the sum of energy is 0 and there is friction.
There is no need to go any further. You have just proved it cannot produce free energy.
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There is no need to go any further.
Ok, I understand for one screw (for one screw I knew sum of energy is 0) but not for two, it's the problem for me and if I need to explain I can't say with 2 screws it's the same problem... Just for understand the all system ;) Please :)
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But I don't understand the system. I don't even know what you mean by "pressure". Is this a fluid pressure, or are you really referring to a force?
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sorry, I'm not fluently in english and I'm not a specialist in physics :(
"pressure": it's air pressure (for example, use anybody fluid) at 1 bar, 2 bars or 3 bars
ask me if you don't understand others things in my message
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OK - So what you have is two screws that mesh together and form a gas-tight seal where they touch (no leaks) and the seal encloses a volume of high pressure gas. The two screws are rotated by some external gearing system.
What is suppsed to happen when the screws are rotated?
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What is suppsed to happen when the screws are rotated?
With 2 screws, each screw is a motor it give energy to a mechanical receptor (if friction is low). Screws are not receptors they are motors. It's not a screw which give a torque to another. This is the differential of pressure of fluid that give a motor torque to each screw. Like screws give energy to receptors we need lost energy somewhere, where ?
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Ah, right.
So the thing is a motor that is driven by the P3 pressure?
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"the thing" ?
Black screw has everywhere around it 3 bars except at interface (small volumes between screws) where pressure is 2 bars => the screw turn and give a torque
Red screw has everywhere around it 1 bar except at interface (small volumes between screws) where pressure is 2 bars => the screw turn and give a torque
Like screws turns and can't move in translation, interfaces (small volumes between screws) move up/down, but each interface is composed by 2 surfaces from screws and 2 gaskets's surfaces. Like 2 gaskets's surfaces can be in longitudinal axis we don't lost energy when the interface move.
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"the thing" = the device.
OK, so why would the higher pressure make the screws rotate?
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It's differential of pressure of fluid that rotate each screw. Each screw can only turn (bearing). We can thinking with only one screw, the black for example, it has all around 3 bars except at small surface where pressure is 2 bars. This rotate the screw I think ? See drawing please.
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But differential pressure will not produce rotation. There is differential pressure between the inside and outside of your bottle of Fanta, but nothing actually happens until you take the cap off the bottle.
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but the red surface move it's not a static surface, follow the screw, move in translation.
And the red surface is only on one side of the screw, not 2 sides. See drawing please.
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You are missing a very important point.
The screws enclose a constant volume of gas even when they are rotated by an external force. It's just the same as the gas inside a sealed bottle. Differential pressure won't do anything uless you allow the gas to expand.
Engines that use gas to do work, like turbines, pistons etc. are frequently called "expanders" for that reason.
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The screws enclose a constant volume of gas even when they are rotated by an external force. It's just the same as the gas inside a sealed bottle. Differential pressure won't do anything uless you allow the gas to expand.
You're explain for 2 screws or one ? If it's for 2 screws, I'm agree with your explanation but I'm trying to understand this device with sum of forces (torques too). Because my son can only understand this, sorry :(
It's not the sum of forces that rotate screws ?
For you one screw turn like that (for me one srew turn, it's only a problem with sum of forces, sure with one screw I can explain sum of energy is 0, the difference of pressure rotate with torque the screw but I need the same energy for move red surface) ? If yes, why two screws don't rotate (explanation with forces) ? My son come back tomorrow and I would like to explain this wk, thanks for your help :)
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Just because there is a force, it does not mean there is a transfer of energy.
The mechanism you describe prevents the "3P" volume from ever changing. If you think there is an energy transfer (which is the basis of all machines that do work) you need to explain how the volume changes.
If you look at it very carefully, you will discover that the volume never changes, so it might as well be a bottle of Fanta.
It's cleverly designed to deceive, but if you want it to do anything useful, one of the spirals has to be reversed as it is in supercharger link I posted.
Do you think the volume changes?
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No, for me the volume don't change, the device is like that. I understand your point of view and it's ok for the sum of energy when I think with volume/pressure. But when I think with force, I see a force that rotate each screw in the same direction, I don't understand why there is no torque ? The torque come from force, like force is not 0, torque is not 0. And like screws can turn mechanically they can give energy to receptors. For me there is a contradiction here.
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I think the problem is that there really is no differential pressure, even though the drawaing suggests there should be. I don't understand how the seals (gaskets) described are supposed to be arranged in a real system.
If you can draw a practical arrangement, I think you will find the forces all sum to zero.
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This afternoon, I'll build 2 helicoids in cardboard for my son, like that we can see the exact volume and gaskets's surfaces. For now, a 3d software give the interface like the drawing show, for me it's like I see with 2 real screws I have in front of me. Second drawing is top view for see gaskets's surfaces are in longitudinal axis.
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All is fine with sum of energy. In fact it was the separation (sides) of fixed pressure, walls can't stay fixed, they need to move and this lost energy.