Submarine Propulsion

taylaron

Submarine propulsion

Regarding nuclear powered submarines, they produce electric energy through the use of a generator that is being powered by steam from a “boiler” –for simplicity-
Would this energy be enough to power a submarine using magnetohydrodynamic water propulsion? Using electricity to power a device that uses the electricity to move water through this “chamber” that runs the length of the ship?

Article found on magnetohydrodynamic water propulsion found at:
http://www.spots.ab.ca/~belfroy/magnetohydrodynamics/magnetoWaterPropulsion.html


This could be the key to “silent” submarines if possible.
I’m no physicist and am simply curious wither a submarines electrical output is enough to move enough water for a submarine to move significantly.
I know Honda experimented on magnetohydrodynamic water propulsion, and failed. But they don’t have nuclear power plants aboard their boats do they…..

I also know that they use electrolysis to make pure water and oxygen for their extended underwater travels. Magnetohydrodynamic propulsion expels water flow, hydrogen, and oxygen (from separating the hydrogen and oxygen in the water).
They could use this electrolysis for their oxygen and water supply. Neat and efficient.
The bad thing is, if it was possible, it would already be done. I’m afraid my perspectives on the required energy are way off.


Thank you everybody

taylaron

anybody?
some input would would be great.

Morbius

taylaron,

Have you been watching "Hunt for Red October"?

The generators in subs are sized to provide the electrical needs of the sub,
but that doesn't mean they can't be sized to convert the entire turbine
output to electricity - as in a land-based commercial power plant.

The question I would have would be if magnetohydrodynamics would be
"gilding a lilly". One would have to know what the real noise makers are
on a sub.

Certainly propellors CAN be noise makers, but the Navy has put a lot of
work into making propellors as quiet as possible. The machining of propellors
is done very precisely. Toshiba got into trouble several years back when it
was discovered that they sold machining equipment with proprietary US
technology to Russia; which used that equipment to make quieter props for
Russian subs.

http://lubbers-line.blogspot.com/200...age-again.html

However, suppose the turbine were the noisiest device on the sub. Then it
wouldn't make sense to go with MHD; because you would still have the
turbine noise.

I would bet that the U.S. Navy is making subs as quiet as possible within the
limits of current technology.

Dr. Gregory Greenman
Physicist

3trQN

Japan successfully ran a Prototype MHD Ship the Yamoto 1 Apparently.

Astronuc

While true, the speed was limited to 15 km/h (8 knots), they did not have to be concerned with 'noise' and I am quite sure they used conventional marine power systems rather than a nuclear plant, and the ships had a relatively limited demonstration period.

As Morbius indicated, the Navy is constantly looking for ways to make submarines quieter, as well as more reliable and less costly. The US Navy has certainly looked into MHD.

taylaron

i've seen the hunt for red october and i was assuming that the "caterpiller drive" was some sort of MHD engine. although i dont recall them ever calling it that.

thank you all for your help.

and happy new year

taylaron

so does MHD technology pose any usefullness in the near future? in your opinion.

Morbius

taylaron,

In the movie, "Hunt for Red October", I believe Ryan is told that the
catepillar is an MHD device by the "sub-driver" [ former sub captain ]
Oliver Wendell "Skip" Tyler; that he came to the USA to see.

Dr. Gregory Greenman
Physicist

taylaron

thanks morbius for your help

sanman

The coupling effect for MHD seems very poor.

taylaron

I know this is going off topic but,
For submersible vehicles for underwater exploration, they have a definite depth limit due to the integrity of the hull correct? the inside of these vehicles are full of air and pose a problem with implosion/folding when going too deep. Because you cant compress liquids, why not build a vehicle that is filled with a non-conductive liquid? Because water is a conductor, if the thing is filled, it will naturally fry the electronics. But if it was filled with a liquid that doesn’t conduct electricity. wouldn’t this dramatically help the maximum depth problem? im merely curious, I don’t know if they're already doing this.
Thank you for your time.

LURCH

Up until recently, you would have one that bet. However, the Germans appear to have beat us out with their hydrogen fuel cell powered submarine .

It is now the worlds quietest submarine, which nicely illustrates your point about the chief source of noise being something other than the propeller. The new Germans sub uses a propeller, just like nuclear powered American subs, but because it uses hydrogen fuel cells rather than a reactor, it is much quieter, because it does not have "the noise of the reactors cooling system", according to one interview I saw on, TLC.

Morbius

LURCH,

More likely the noise of the TURBINE and reduction GEARS!!!

The Navy submarine cooling systems are very quiet - can't elaborate here.

The noise is from mechanical sources - a fast spinning turbine, and the gearing that
it takes to reduce the speed to much slower speeds of the sub's propellor.

I would bet the German subs use low RPM motors to turn the propellor, thus eliminating
the need for reduction gearing.

The German subs are quiet - but they are SLOOOOWWW compared to a US nuclear
sub. They may be able to sneak up on a nuke - but they most certainly can't run from
a nuke.

Dr. Gregory Greenman
Physicist

russ_watters

That's just a slightly better diesel sub - diesel subs are always the quietest subs (an electric motor running off a battery is very quiet), but they have a pretty severe drawback in that they require air to run the engines to charge the batteries.

The US very likely still holds the title when it comes to subs that can stay underwater for long periods of time (months rather than days).

[edit: Wik says 3 weeks. That would surprise me. Perhaps it is 3 weeks if they don't move...]

berkeman

Like, fill the submarine with oxygenated Flourinert?

http://en.wikipedia.org/wiki/Flourinert

Then train all the submariners to breath the stuff, and give them special glasses so that they can focus on the displays and see still. Kind of like (what was the name of that movie....something like The Deep or The Chasm?....with the John Glenn actor guy?)

Morbius

Russ,

I think you were correct the first time - it's more like months.

The Trident SSBN "boomers" certainly can stay submerged for months - that's how they
hide. The basic limitation on how long a Trident can remain at sea, and remain submerged
is how much food they can carry.

The sub can make it's own fresh water and oxygen from seawater.

A good book on life on a Trident is:

"Big Red: The Three-Month Voyage of a Trident Nuclear Submarine"
by Douglas C. Waller

http://www.amazon.com/Big-Red-Three-...e=UTF8&s=books

Dr. Gregory Greenman
Physicist

LURCH

The "three weeks' was for the German sub.