A Homemade Magnetohydrodynamic Thruster (MHDT)
Based on the image on the left, it is possible to make a simple MHD thruster, just powerful enough to propel a toy boat.
This type of thruster generates magnetic fields by passing an electric current through a liquid conductor, such as sea water. Using another magnetic field, the liquid can be pushed in a chosen direction, therefore generating thrust. You can easily make one of these devices from household materials and a couple of neodymium magnets. In the diagram below the small arrows represent the intersecting electric and magnetic fields. the large blue arrow represents the flow of water.
Two opposing inner faces of a rectangular plastic tube are covered by metal strips. These are the main electrodes and should have a connection for a battery. Magnets are attached on the outside of the tube so that they are attracting each other, and are at 90° to the electrodes.
The metal strips here are cut from a thin Aluminium sheet, but you can just use foil although it wont last as long. The electrolysis and salt water corrosion soon eats away at the metal, but foil should last just long enough to see it working. The best sort of electrode would possibly be made from carbon. A good power source for this device would be a pulse width modulated supply such as our power pulse modulator. This would allow you to adjust the frequency and width of electical pulses so that you could get the optimum thrust from your design.
To learn how a MagnetoHydroDynamic thruster works, see the Propulsion section.
This setup shows the electrodes closer together than the magnets. The combination of magnets used in this device were not strong enough to move the electrified water with any decent force. At only 1.5V in salty water, large amounts of electrolysis occurs, but the water does generally flow in one direction.
The key to getting the best performance it to have the strongest magnetic field you can get across the gap between the electrodes.
Also make sure the magnets are behind the plastic or insulated somehow. You don't want them shorting out the electric current in the water.
The information provided here can not be guaranteed as accurate or correct. Always check with an alternate source before following any suggestions made here.
I am planning to use for the MHDT. How wide should I make
the tube?
Thanks,
IM
i have been researching HHO generation for a while as a hobby. my aim: to fuel a petrolengine in a car with a mix of 50/50 petrol and HHO. The hho-cell is made of stainless steel plates in tapwater @ 12vAC 10-20 amps. i get about 1 liter/minute of gas production. How about converting the cell to create a "flow" with neodymium magnets would this enhance the electrolysis process and how would it inpact energy consumption?
greetings
Using magnets in your cell would have virtually no effect as the cell overall is neutrally charged (uncharged).
see it ...http://fr.youtube.com/watch?v=sT39rd4P9x4
You can't increase the voltage without increasing the current and visa-versa. See Ohms Law.
I've no idea what you are talking about at the end of your post!
"Stronger magnets or more current will improve performance equally. Using more current though will heat the water and waste some energy. You should use the strongest magnets possible to improve efficiency.
You can't increase the voltage without increasing the current and visa-versa. See Ohms Law.
I've no idea what you are talking about at the end of your post!"
I am not sure you are entirely right about not being able to raise voltage without raising current. What about something like a Van de Graaff generator being used to power the unit. It creates incredibly high voltage but little current and is an extreme example of what I meant. Why would it not be possible to run this thing in this way? (not neccesarily using a Van De Graff machine) I was always under the impression that current and voltage were different things. Using the anology of water,HV without much current would be like holding your thumb over the end of a water hose. The pressure would be greatly increased yet the actual flow would not. High current yet low current would be like a very wide yet slow moving stream. Another analogy. High voltage yet low current would be like a lead bullet shot out of a gun at high speed. High current, yet low voltage would be like me throwing a very large and heavy lead weight. Both could cause damage, yet in different ways. As for my question about using opposing magnetic fields (N-N, S-S) I think I found the answer to that myself, but please help me to understand if I am wrong. This would either cause the water to not move at all becuase the magnetic field would cancel itself out since it would be moving in opposite directions-OR- it may cause some water to move one way and other to move in the opposite direction dep. on which was closer to which pole. Or am I not understanding that concept??? As for my question at the end of my other post-I have no idea what I was talking about either!
Plus a NEW question-If instead of using magnets you used electromagnets set up in the same way, and from the same power source-and furthermore if this powersource was AC and not DC-then would this not work pretty much the same since both the current and the electromags were run of the same source-they would both(magnets-and electric current)switch polarities at the same time? would this be true of the current moving through the salt water or would there be an increased resistance which would cause a delay which may make the whole thing not work. Assuming it works just fine, however, would it poss. work even better this way, or even perhaps less well. If either would be true please explain why. Also should I ask a priest for forgiveness if I comit a sin against nature-for instance-if I where to create some frankensteinian-unholy-abomination to both nature and man. Would a small hydroelectromagnetic craft be such an abomination, or would I have to resort to science involving a radical reassesment of where life begins and ends, perhaps creating an experiment which redifines such things in such a way as to send shock waves of moral and scientific indignation and disbelief?
When calculating using ohms law you have to include all of the circuit, this includes the power supply. Any power supply has its own internal resistance.
Whatever way you do it, the physics will make ohms law true always.
If you have magnets facing like to like poles, the magnetic field lines will not be at 90 degrees to the electric field. This would cause the water to move in other directions or not at all. It would be quite useless.
You could get stronger fields using electromagnets, but using AC would cause the water to move back and forth, thus giving no net thrust in one direction. If you arranged it so that the magnets also change polarity with the field you could get thrust, but it wouldn't help. Using AC would also add some impedance to the circuit.
A priest can't help you. A priest is just a man who claims to represent a god. A god that he can't communicate with in any way. He is just a man who represents the ideas of other men who use the name of god without any divine authority. If you feel that you committed a "sin" then you have to learn to deal with it your self, try to make up for it in other ways. The only persons advice you may need is that of a lawyer because there are laws to prevent certain experiments from being done. If whatever you do is within the law and does not make you feel like it is immoral or wrong, then it is probably OK.
The part you quote is about non-linear electronic components. Such components have semiconductor junctions that change the way electricity flows in them. Salt water is a 'standard' linear material and will obey ohms law.
If you had a high voltage, high current source, the spark would be very different to that of a VDG. Air is a dielectric (non-conductor) when the voltage is high enough a phenomenon of avalanche breakdown occurs allowing it to conduct.
Salt water is normally conductive and does not break down in order to allow current to flow. You can test ohms law on salt water yourself very easily.
I said nothing blasphemous. I just presented a series of facts about men, not gods. I don't need or want forgiveness of any sort from a priest, but I am happy to answer science questions if he emails them to me.
Voltage and Amperage can be dealt with as totally independent factors, but used together, they have a measurement we call Watts, which implies the ability to do work(Watts can be converted to other units, such as Horse Power, for direct comparison of the afore mentioned ability to do work).
Didn't notice this discussion before :-)
I tried to build one of those "railguns for water", but it seems like it needs a lot of tinkering to get it to work properly, sort of the same problem as if you make a normal electrical motor but instead of a coil you just have a single wire. I works, but the efficiency is "shit". I can imagine that if you manage to get several places within the tunnel that conduct, and you get them far enough from each other, so that you end up with separate "conducting areas", maby you could connect those in series to imitate a sort of coil? hmm.. well, when i think more about it, seems like a coil is a bit different, but ... ach, i dont know :-)
What if you use air instead? Let's preted we take the ignition coil of a car, a 30 000V capacitor and high voltage diode, something that pulses the coil, end some strong magnets? Then you adjust the air gap between the electrodes so that you get a constant spark. I would do this myself if i had the time and money :-/ (mostly it's the time that is lacking, it shouldn't cost a lot to build)
If nothing else you end up with a kick-ass tazer :-)
I can see the problem though, it would have the same issue as the one with saltwater in it, crappy efficiency. It would just look and sound cooler hehe :-)
You need to learn about ohms law so that you can understand that your question can't be answered in the way you are thinking.
Your wire will have a set value of resistance which is determined by its diameter, length, material, and temperature. For this example, lets say that value is 0.1 ohms and we will ignore any variation in temperature etc.
Ohms law states that V = IR (voltage = current times resistance)
If the voltage is 10V, then the the current flowing must be 100 amps because 100 x 0.1 = 10
If you change the voltage, the current will change too. So in your questions A,B,C, to have those values, the wires resistance would be different and it is therefore impossible to have those values on the same piece of wire. A = 1 ohm, B = 100 ohms, C = 10,000 ohms