Magnetohydrodynamic drive

MHA test vehicle Yamato 1

A magnetohydrodynamic drive , also called MHA ( magnetohydrodynamic drive , MHD), is a drive principle for watercraft .

Such a device can be seen as a reversal of the magnetohydrodynamic generator : while there the moving water in the magnetic field creates a current between the collector plates, here the current in the magnetic field sets the water in motion.

Since no propellers or other mechanically moving parts are used for movement, the drive is practically noiseless.

Functional prototypes have already been built in both the USA and Japan, but the necessary high magnetic flux densities and electrical currents make operation unprofitable.

functionality

An electric and a magnetic field are built up perpendicular to the desired direction of movement and perpendicular to each other . The electrolysis of the water causes a current in the direction of the electric field, the charge carriers of which are deflected by the Lorentz force in the magnetic field. This sets the water in motion along the direction of the jet, and the recoil drives the ship.

The Lorentz force on a conductor the length through which a current flows is equal to the field strength in the magnetic field ${\displaystyle d}$ ${\displaystyle I}$ ${\displaystyle B}$

${\displaystyle {\vec {F}}=I{\vec {d}}\times {\vec {B}}}$,

where here represents the distance between the electrodes. The available driving force is only relatively small , even with magnetic flux densities of several Tesla and currents of several thousand amperes . ${\displaystyle d}$

Prototypes

In 1966, the first MHA drive was successfully tested in a model submarine , the EMS-1 , off the coast of California.

In the 1980 and 1990s in Japan, u. a. built by Mitsubishi , models and prototypes of MHA-powered ships (e.g. SEMD-1, ST-500). The vehicles reached speeds of around 15 km / h, although numerous difficulties arose.

Yamato 1

In June 1992 the experimental ship, the Yamato 1 (30 m long, 10 m wide, displacement 185 t, crew ten people (three crew and seven passengers)) was tested in the port of Kobe . The ship was largely made of an aluminum alloy (JIS A 5083) and powered by two magnetohydrodynamic engines. The propulsion system worked in a similar way to a water jet propulsion system : Seawater was expelled here at an accelerated rate by the Lorentz force at the stern of the ship. The magnetic fields required for this purpose have been provided with liquid helium cooled niobium / titanium - superconductor generated.

A Yamato 1 engine

Magnetic flux densities of 4  Tesla were used. The Yamato 1 is today in front of the Naval Museum in Kobe.

Drive concept also in space travel

Conceptually analogous, but working with the medium plasma , the magnetoplasmadynamic drive for space vehicles is an active research topic.

Trivia

In the movie Hunt for Red October 1990, an MHA was thematized, which could drive a new, fictional submarine silently. In contrast to this film, the subject of the literature was a submarine with a water jet drive .

In several of Clive Cussler's books there are ships and submarines with magnetohydrodynamic propulsion. In the Oregon series books, the Oregon is equipped with this drive.

In the scientific and didactic comic "The magnetic sound barrier" from the series The Adventures of Anselm Wüßtegern by the French physicist Jean-Pierre Petit , the magnetohydrodynamic drive is the theme.

literature

• Kazu Nishigaki, et al .: Elementary study on superconducting electromagnetic ships with helical insulation wall , Cryogenics, Vol. 40, Issue 6, 2000, pp. 353-359. doi : 10.1016 / S0011-2275 (00) 00049-7 .
• D. L. Mitchell et al .: Magnetohydrodynamic ship propulsion with superconducting magnets , Journal of Superconductivity, Volume 1, Number 4, pp. 349-364. doi : 10.1007 / BF00618593 .

Individual evidence

1. ^ S. Takezawa et al .: Operation of the Thruster for Superconducting Electromagnetohydrodynamic Propulsion Ship "YAMATO 1". (PDF; 257 kB) Marine Engineering Society in Japan, March 1995, accessed on March 3, 2016 (English). 
2. ^ "S. Way tried to conduct the worlds first sea trial for the MHD-propelled model submarine EMS 1 ...", in: Yohei Sasakawa: Yamato-1 - the world's first superconducting MHD propulsion ship. Ship & Ocean Foundation, Tokyo 1997, ISBN 4-916148-02-9 .
3. ^ Technology: Run Silent, Run Electromagnetic. Time, September 23, 1966; accessed December 6, 2010 . 
4. ^ TR Reid: Ship Sails on High-Tech, 'Silent' Drive. (Free article preview) Japan Tests New Propulsion System Reminiscent of 'Red October'. The Washington Post, June 17, 1992, accessed December 6, 2010 . 
5. ↑ TR Reid: Japanese Ship's Magnetic Attraction. (Free article preview) Revolutionary Drive Design Lacks Moving Parts. The Washington Post, June 22, 1992, accessed December 6, 2010 . 
6. ^ Colin Nickerson: Engineering - May The Force Be With You. The Seattle Times, July 20, 1992, accessed December 6, 2010 . 
7. ↑ Yohei Sasakawa: Yamato-1 - the world's first superconducting MHD propulsion ship , Ship & Ocean Foundation, Tokyo, 1997, ISBN 4-916148-02-9 , pp 10-15.
8. ↑ Dennis Normile, Robert Langreth: Supercon Goes to Sea. (Google books) Popular Science, November 1992, accessed December 6, 2010 . 
9. ^ Jean-Pierre Petit: The magnetic sound barrier , PDF file, German; 3.4 MB, accessed June 16, 2019