Talk:Magnetohydrodynamic drive

Question

Hello this is a test. An experimental MHD drive was installed onto the Russian submarine Red October in the movie The Hunt For Red October. This drive allowed the sub to be nearly silent (and thus undetectable) while moving. As the MHD drive requires a substantial magnetic field, would this not be detectable by a magnetic anomoly detection system (MAD boom) as carried by the anti-submarine warfare (ASW) aircraft of virtually all the worlds navies/air forces? Commercially viable, yes. Undetectable?, possibly not.

Electrolysis

Speaking from experience, when you run a current through salt water, you get hydrogen and chlorine forming by electrolysis. Chlorine is highly corrosive (even compared to salt water), poisonous, and explosive in combination with hydrogen. Since the gases form as bubbles, surely this process is also noisy. So what is done to suppress electrolysis in an MHD engine? Or are the voltages and currents such that nothing need be done? --Andrew 06:41, Apr 24, 2005 (UTC)

Electrolysis reply

You probably would be unable to stop electrolysis occuring. But, I can reason like this: 1. While you are right in that the hydrogen + chlorine reaction is explosive, it only happens if there is available light. In the dark (e.g in an engine) there is absolutely no reaction.

2. Chlorine itself is not corrosive. It reacts with water to form hydrochloric acid and hypochlorous acid, which are. However, in an MHD, the dilute acidic solution would be rapidly ejected from the engine into the sea, whre it would do no harm to the engine.

You are right in that the hydrogen bubbles would remain free, but they may be collected and stored/used.

82.153.169.213 17:44, 13 October 2005 (UTC)

Few MHD comments...

The Red October's Caterpillar drive was thermohydrodynamic, not magnetohydrodynamics, or in other words a nuclear water jet. One thing I never really understood was how they avoided cavitation from boiling water. Then theres also the issue of running the reactor hot enough to heat huge volumes of water at an extremely high rate of speed, if anything went even slightly wrong it would melt down and explode before they even knew what happened.

Magnetic detection is a problem for all subs and I'm not sure a MHD drive would make a difference, certainly wouldn't help. Using different hull materials or layers of materials is another option. It would sacrifice dive depth and general hull strength for increased stealth. Same for acoustic detection, a soft enough material might even be able to adsorb an active sonar ping (e.g. creating a large shadow or “hole�? in the water rather than a well defined shape).

Few literate among these had been made on the spite of the listening with respect to the willingness ok..Other things to consider with next generation subs: hyper-planing rocket propelled torpedoes and hyper-planing bullets. Deep running subs are effectively immune to missiles, bombs, depth charges, etc... Now with hyper-planing bullets they could easily destroy an incoming conventional torpedo well before it poses a serious threat to the sub. Hyper-planing torpedoes allow the sub to hit targets well outside of detection range with a supersonic torpedo that cannot be detected before impacting the target. (note, saying next generation is a bit of a misnomer, China armed their subs with Russian hyper-planing torpedoes over a year ago but last I heard the US is planning to implement them in the next generation of subs towards the end of the decade -- not to mention these 'super torpedoes' are able to carry nuclear warheads).

Back to the subject at hand, another interesting application for MHD drive systems is fighter subs. With advances in fuelcell technology or even compact nuclear reactors, a fighter size sub could run totally silent and kill targets with near impunity (unless the target had hyper-planing bullet based weapons). Just have to work out the technical issues with the drive systems.

The future of naval warfare will be very interesting indeed and I think MHD drives will be a corner stone in that future.

-MegaBurn

In the first sentence you call it a nuclear water jet. But what could possibly be a nuclear water jet? The only thing a nuclear plant can produce is heat, which has to be further processed to get electricity or mechanical power. Your statement doesn't make sense.--Titeuf24 (talk) 01:57, 5 July 2009 (UTC)

Production of gas

My understanding is it is possible to produce an electric field in water without electrolysis and therefore, the production of gas. If a substance undergoes electrolysis to yield H+ ions and is seperated from the (sea?) water by a semi-permeable membrane that allows the passage of H+ ions but nothing else, then excess H+ ions could be forced into the sea water. The negative ions at the cathode would be protected by a similar semi-permeable membrane, with the result that H+ ions would leave the anode and migrate through seawater to the cathode, thus resulting in an electric field in the water. As neither electrode makes direct contact with the water, electrolysis does not take place. Application of a magnetic field perpendicular to the direction of the electric field would result in the magnetohydrodynamic drive as described by the article. This line of reasoning occurs to me as neurones produce electric fields across their membranes via the hydrolysis of ATP routinely, and do so without generating gas from the hydrolysis of water. In such a system, the electric field may be maintained as long as a steady supply of ATP (or other high energy proton source)is provided. Please note that I am not a trained chemist, rather a biologist, and my understanding of this phenomenon may be mistaken.

Removing Probable HOAX

Conservation of Energy and a host of other engineering perameters make this paragraph extremely doubtful. Suggest it needs multiple cites from 'reputable publications, NOT from COLLEGE pages w/likely 'prank's to support it 'factually' before it restoring it to the article.

An example would be Japan, which began sea trials of a prototype magnetic ship. Yamato 1 is propelled by two MHD (magnetohydrodynamic) thrusters that run without any moving parts. When completed, the MHD ship should be able to attain speeds of more than 100 knots (125 miles or 200 kilometers per hour), with little noise. This is several times the top speed of today’s ships, which are slowed down by turbulence created by the ship’s propellers. MHD works by applying a magnetic field to an electrically conducting fluid. The electrically conducting fluid used in the MHD thruster of the Yamoto 1 is seawater. [1]

http://en.wikipedia.org/w/index.php?title=Magnetohydrodynamic_drive&action=edit

The material cited is now four years old, and if reputible results exist, they should be more available than something this skimpy and unreliably edited. FrankB 21:13, 1 June 2006 (UTC)

1. What does this have to do with conservation of energy?
2. Here is a reference that looks legit at first glance: [2]
3. And another [3]
4. And another [4] — Omegatron 21:45, 1 June 2006 (UTC)

Merge with Caterpillar drive

I'd say yes to this merge, afterall they're the same thing. One just uses a puncher name (designed to inspire the imaginations of film goers) and the other a technical name. --62.173.194.7 08:05, 24 July 2006 (UTC)

The caterpillar is the underwater equivalent of a jet, not an MHD. Like in all conversions(I just know I'm using the wrong word), details were changed when the screenplay was written. In the book(which should always be preferred over the movie in this kind of situation), the caterpillar is driven by impellers. The article needs to be rewritten to show this. BioTube 00:28, 24 September 2006 (UTC)

Clarify the engine/generator part?

"The major problem with MHD is that with current technologies it is more expensive and much slower than a propeller driven by an engine. The extra expense is from the large generator that must be driven by an engine. Such a large generator is not required when an engine directly drives a propeller."

So, if it's still driven by an engine powering a generator...what's the point of the MHD? —Preceding unsigned comment added by 146.145.251.34 (talk) 20:16, 23 November 2010 (UTC)

History of Magnetohydrodynamic Propulsion

Magneto-hydrodynamic Propulsion was first used in experimental German submarines in 1933. The Germans also tried it to propel torpedoes, but the gases produced were visually more noticeable and they were very acoustically noisy, as well, so this was abandoned in favour of chemical propulsion in which the reaction products were dissolvable in seawater to conceal the wake. They could not get sufficient thrust from this, so they returned to using propellors and put up with the cavitation wake they produced because they were so much faster, which meant that the target had insufficient time to react. The Magneto-hydrodynamic propulsion of submarines was similarly abandoned because of the acoustic and magnetic noise and because low RPM propellors and electric motors were far less detectable. — Preceding unsigned comment added by 203.142.148.196 (talk) 02:26, 31 December 2011 (UTC)

Can't magnetohydrodynamic drive theory be used in jet engines? If it needs high voltage of electricity, couldn't it provided with battery power for passenger jets like Air Bus? If we could achieve this we could reduce the cost of air travel and passenger risk if the jet crashes. — Preceding unsigned comment added by Mihinduep (talk • contribs) 01:38, 24 April 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Magnetohydrodynamic drive/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Article needs an expert in magnetohydrodynamics and expansion. In-line citations are needed. Additional references(Properly formatted) are needed. --Xp54321 (Hello! • Contribs) 19:19, 31 August 2008 (UTC)

Last edited at 19:19, 31 August 2008 (UTC). Substituted at 22:50, 29 April 2016 (UTC)

Supposed reasons for impracticality -- a generator and (possibly) low efficiency

The lede says "MHD drives remain impractical due to... the large amount of energy needed to operate them," implying that efficiency is low. But the article says precious little about actual efficiency. It would be nice to have a section, however brief, that describes MHD efficiency.

The article goes on to say "The major problem with MHD is that with current technologies, it is more expensive, and much slower, than a propeller driven by an engine. The extra expense is from the large generator that must be driven by an engine. Such a large generator is not required when an engine directly drives a propeller."

As written, this is dubious. A diesel-electric locomotive is not driven directly by an engine; instead, a diesel generator creates electric power which drives electric motors.

Now, there may be a valid reason why the need for a generator is not a problem on a locomotive, but is a deal-breaker on a marine vessel. If so, the article should explain it. Novel compound (talk) 21:35, 17 September 2017 (UTC)

Fact or fiction

This article contains some good, sourced material, but mixed in with that much of it is unsourced speculation reminiscent of science fiction. Examples will follow. Andrewa (talk) 22:52, 12 April 2020 (UTC)

Electro Magnetic Flow Meter

Electromagnetic Flowmeters measure flow of conductive fluids with no moving parts using the MHD Generator principle. https://en.wikipedia.org/wiki/Magnetic_flow_meter — Preceding unsigned comment added by 194.54.168.71 (talk • contribs) 12:10, 25 February 2021 (UTC)

Not really. ~Anachronist (talk) 18:07, 25 February 2021 (UTC)

Active flow control

It says:

"Active flow control by MHD force fields on the contrary involves a direct and imperious action of forces"

"Imperious"? How can a force's action be imperious? Can anyone say whether perhaps there's a typo, and some other word was intended?

MrDemeanour (talk) 14:55, 26 May 2023 (UTC)