Magnetic flux control idea

[citfta]

Hi Vidar,

You are proposing an interesting experiment.  I am familiar with someone who built a bouyancy wheel like you posted at first.  He built a much smaller version and did quite a bit of analysis on it.  It was too small to turn under its own power but a test he did showed something interesting.  He used a small DC motor to drive the wheel in one direction and turned the current down until the wheel would stop.  He recorded the minimum amount of current required to keep the wheel turning.  He then did the same thing turning the wheel the opposite direction.  He found that it required quite a bit more current to keep the wheel turning against the direction you would expect it to go if it could power itself.  He and several of us were convinced that a much larger wheel would probably turn under its own power.  But the complications of building it larger got the project put on the back burner I think. 



To test your device you might also try driving it one way and then the other.  The only problem with that is you need to make sure your motor draws the same amount of current in both directions when loaded the same.  I have worked with motors for many years and some are more efficient one way than the other.  Or you could drive the wheel on one side and then drive it from the other side to keep the motor turning the same way both times.



There are several areas of that design that can add a lot of friction to the free turning of the wheel.  I am afraid you will also run in to some of those areas.  One improvement you have made is the idea of using a bellows between the wheels.  If I recall correctly he had a solid box around the wheels with seals where the wheels met the box.  He said those seals were contributing a lot of drag.

The other area of drag was the friction caused by the tubes sliding in and out of the wheels.  I don't know anything about the ferrofluid.  Is it slippery like a lubricant?  That might help reduce the friction in this area.


Good luck,
Carroll

[tinman]

Hi Vidar,

You are proposing an interesting experiment.  I am familiar with someone who built a bouyancy wheel like you posted at first.  He built a much smaller version and did quite a bit of analysis on it.  It was too small to turn under its own power but a test he did showed something interesting.  He used a small DC motor to drive the wheel in one direction and turned the current down until the wheel would stop.  He recorded the minimum amount of current required to keep the wheel turning.  He then did the same thing turning the wheel the opposite direction.  He found that it required quite a bit more current to keep the wheel turning against the direction you would expect it to go if it could power itself.  He and several of us were convinced that a much larger wheel would probably turn under its own power.  But the complications of building it larger got the project put on the back burner I think.  



To test your device you might also try driving it one way and then the other.  The only problem with that is you need to make sure your motor draws the same amount of current in both directions when loaded the same.  I have worked with motors for many years and some are more efficient one way than the other.  Or you could drive the wheel on one side and then drive it from the other side to keep the motor turning the same way both times.



There are several areas of that design that can add a lot of friction to the free turning of the wheel.  I am afraid you will also run in to some of those areas.  One improvement you have made is the idea of using a bellows between the wheels.  If I recall correctly he had a solid box around the wheels with seals where the wheels met the box.  He said those seals were contributing a lot of drag.

The other area of drag was the friction caused by the tubes sliding in and out of the wheels.  I don't know anything about the ferrofluid.  Is it slippery like a lubricant?  That might help reduce the friction in this area.


Good luck,
Carroll

It was more a case of working out why it would not work.

One thing low-Q needs to take into consideration is that the ferro fluid will also become magnetic around the steel pins,as the steel pins will become temporary magnets while in the magnetic field of the PMs. This in turn (virtually) increases the volume(weight) of the steel pins,and decreases the volume of the liquid ferrofluid.

So the net work done by the PMs on the steel rods on either side of the axis point sums to 0.


Brad

[Low-Q]

@Carrol
The motor used on the buoyancy wheel might suffer from the difference in efficiency. This can be adjusted on regular DC-motors by turning the commetators a little bit one way or the other, so the timing on the rotating electromagnets is equal in both directions.
The reason why his device got more volume on one side than the other, is because of the angle between the wheels. This angle also increase the surface area in front of each tube which will cause greater force in front of the tube than behind them. This counterforce is caused by the same angle that makes greater volume on the wide side than the narrow side. So these two forces adds up to zero.
Btw, even if steel rods doesn't float on water, he could likely used steel rods instead of hallow tubes.
The difference in buoyancy is the same

My ferrofluid is very slippery. It is some sort of silicone oil with magnetite powder in it.




@Brad
I can absolutely agree with you. Ferrofluid becomes a magnet. Strongest closest to the PM, but it also increase the pressure in the fluid which will make the steel rods more bouyant. Therfor harder for the steel rods to displace the fluid when they enter this area of higher compression. So what the magnetic field is attracting, the increased pressure will counterforce. So I don't think the attraction at the bottom is the main obstacle, but maybe it is.
However, something must account for conservation of energy. Cannot disagree on this.
I need to say that this is just a hobby. Much of my hobbies is creating problems at will, and then try to solve them - a troublemaker that cleans up after himself


Vidar

[Low-Q]

3D printed bellow. I need to redo this one. Too poor bonding between the layers. And I need to extend it a bit with one more section.
https://youtu.be/qNNiBpVd5jg


Vidar

[Low-Q]

Better but still small holes. Another material, with the same printer settings.


Vidar