Trying to create MHD drive for a boat

[Lingrod]

TL;DR Summary

MHD boat experiment issue

Hello,

I am trying to create a MHD boat.

With my magnet and my generator, which generates a current of 10A, I can create a rapid flow. However, the cable connecting the electrodes to the generator generates a force that prevents my boat from moving forward. I've tried different types of cable, more or less rigid, but my boat just can't cope with the torsion force. Does anyone have similar problems or an idea (other than a battery, I'd like to vary the voltage) to solve my problem?

 

[Baluncore]

Welcome to PF.
Is this an experiment on a full size, or on a scale model?
In it in freshwater or seawater?
Where are you doing the tests?
If you experiment in a test tank, your boat can remain by the generator.

 

[sophiecentaur]

TL;DR Summary: MHD boat experiment issue

However, the cable connecting the electrodes to the generator generates a force that prevents my boat from moving forward.

Which direction does this force appear to act? If you want a supply that has little effect on the boat, I could suggest using two overhead wires (as on a tram), spaced out to produce a correcting torque.I can see that could be too complex for you.
Do you have a diagram of the system?

 

[Tom.G]

Co-axial cable feed feed wires?

 

[Lingrod]

Hello everyone, thank you for your answers, in reality I don't think I have enough flux to move my little polystirene boat.

The reason I've only come to see you now is that I've more or less abandoned my boat project to concentrate solely on propulsion by studying the flow of water between 2 copper electrodes of various sizes and magnets of various powers in several configurations and in more or less ionized water.

However, I still have a small problem: I'd like to determine the impact of electrolysis on my system, but I'm not sure how to go about it. My first idea is to calculate the Laplace force, and thus perhaps make a comparison with the total electrical power supplied, but I don't know where to include electrolysis in my equation.

 

[berkeman]

but I don't know where to include electrolysis in my equation.

Can you show us the math you have so far?

 

[Baluncore]

I'd like to determine the impact of electrolysis on my system, but I'm not sure how to go about it.

For a DC drive current, with permanent magnets, you will need to use carbon electrodes to avoid loss of electrode material. The carbon will develop a polarised layer, as ions from the (sea)water are plated on, or stripped off the electrodes when in reverse.

Commercial MHD generators have a wound field magnet, and produce AC, so they have less electrode problems. Your boat could also use AC.

Don't feel too bad if your MHD boat consumes electrodes. A normal boat leaves a chemical trace in its wake. That ionic signature lasts for some time after it passes. It is often sufficiently detailed, to identify the boat.