Submarine Propulsion

  1. taylaron

    taylaron 388
    Gold Member

    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:

    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
  2. jcsd
  3. taylaron

    taylaron 388
    Gold Member

    some input would would be great.
  4. Morbius

    Morbius 1,160
    Science Advisor


    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.

    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
    Last edited: Dec 31, 2006
  5. Japan successfully ran a Prototype MHD Ship the Yamoto 1 Apparently.
  6. Astronuc

    Staff: Mentor

    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.
  7. taylaron

    taylaron 388
    Gold Member

    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
  8. taylaron

    taylaron 388
    Gold Member

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

    Morbius 1,160
    Science Advisor


    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
    Last edited: Jan 1, 2007
  10. taylaron

    taylaron 388
    Gold Member

    thanks morbius for your help
  11. The coupling effect for MHD seems very poor.
  12. taylaron

    taylaron 388
    Gold Member

    helping depth problems...

    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. :confused:
  13. LURCH

    LURCH 2,507
    Science Advisor

    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.
  14. Morbius

    Morbius 1,160
    Science Advisor


    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
  15. russ_watters

    Staff: Mentor

    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...]
    Last edited: Jan 11, 2007
  16. berkeman

    Staff: Mentor

    Like, fill the submarine with oxygenated 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?)
  17. Morbius

    Morbius 1,160
    Science Advisor


    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

    Dr. Gregory Greenman
  18. LURCH

    LURCH 2,507
    Science Advisor

    The "three weeks' was for the German sub.
  19. taylaron

    taylaron 388
    Gold Member

    rover suggestion

    sounds like the movie "the abyss" by james cameron.
    in this movie i think they use liquid oxygen or something along those lines to "breathe a liquid for insane depths."
    but i was talking about mini remote controlled subs. i suggest filling one up with a non conductive liquid and sealing it shut. wouldent this let the rover go much deeper?
  20. taylaron

    taylaron 388
    Gold Member

    nuclear power and fuel cells

    in a submarine nuclear power plant, one of the forms of radiation is alpha radiation correct and it is identical to helium correct? but does it have orbiting electrons?
    it doesnt say so in wikipedia's
    although it does say it consists of 2 protons and 2 neutrons. no electrons? or did they leave those out for some strange reason?

    i think this is where im wrong
    dispite that probability, i'll go on with my idea

    couldent you take those helium particles and strip the elctrons from them like in the process used by fuel cells? or the same thing by using the beta emissions (high energy, high speed electrons) to produce electricity.

    i think im really screwed up here......:confused: :frown:
  21. It's probably not wise me blowing what little captial I have at this forum being a newb and all, but I put in an SBIR proposal after grad school for a propulsion system, based around manipulating the dipole moments of water using electric field gradients. The system as proposed was too small to be practical and I suppose what was gained in noise suppresion was lost in creating a massive EM signature :)
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