mhd propulsion thruster (2)

MHD propulsion thruster

SEMINAR

MHD PROPULSION THRUSTER

EMIL JACOB ISSAC

S8 MA


ABSTRACT

The Magneto Hydro Dynamic (MHD) propulsion thruster is designed to use magneto

hydrodynamic force generated by sending electric current through a magnetic field created in

sea water by superconducting magnets. The principle of MHD propulsion is to apply the

Fleming's left hand rule of electromagnetics to sea water directly .In this propulsion system

magnetic field is created in sea water by magnets fixed on a hul1. When electric current is sent to

sea water at right angles to the magnetic field, and electromagnetic force (Lorentz force) acts on

sea water in the direction perpendicular to both the direction of magnetic field and that of electric

current. Propu1sion force is gained as a reaction force of this Lorentz force.


INTRODUCTION

MHD

Magneto hydrodynamics involves magnetic fields (magneto) and fluids (hydro) that conduct

electricity and interact (dynamics).MHD technology is based on a fundamental law of

electromagnetism: When a magnetic field and an electric current intersect in a liquid, their

repulsive intersection propels the liquid in a direction perpendicular to both the field and the

current. Hannes Alfven was the first to introduce the term “MHD”.


Thruster


hydrodynamic force generated by sending electric current through a magnetic field created in

sea water by superconducting magnets. The principle of MHD propulsion is to apply the

Fleming's left hand rule of electromagnetics to sea water directly .In this propulsion system

magnetic field is created in sea water by magnets fixed on a hul1. When electric current is sent to

sea water at right angles to the magnetic field, and electromagnetic force (Lorentz force) acts on

sea water in the direction perpendicular to both the direction of magnetic field and that of electric

current. Propu1sion force is gained as a reaction force of this Lorentz force.

.

The Lorentz force F (N) which is the source of thrust force T is given by the formula

F = J X B dv (N)

Here J is a current density vector of infinitesiml volume dv and B is a magnetic flux

density vector of the same. When J and B are constant over the entirevolume V (m3) of the

working part where magnetic fie1d and electric current interact, can be expressed by the

fol1owing formula

F = J X B X V (N)


Thruster Systems

The magnetohydrodynamic (MHD) thruster system for ships with superconducting

electromagnets has been recognized as its potentially attractive performance. Namely, it does not

need any rotating part like conventional propellers or water jet propulsions, and therefore may

be less affected by cavitations, which would be suitable propulsion means for high speed ships

and for ships as specially required silent operation. However, it is still considered that the MHD

thruster system has various kind of difficult problems to be resolved before it could reach

the level of practical use. The problems may be classified into two categories, which are the

technology specifically concerning physical phenomena of superconductors and practical

technique which examines possibility for designing and constructing MHD thruster systems.

This investigation concerns with the later kind of problems. It is considered that MHD thrusters

can be designed


Thruster types

Inner ducting type —A thruster duct is Installed in the lower hull of a SWATH, which

Accelerates seawater for generating thrust force. Two saddle type superconducting coils and

electrodes Installed in the duct generate electromagnetic fields.


Annular ducting type —Superconducting Magnets are composed of several segments which are

installed surrounding the lower hull of a SWATH .The magnets and electrodes form an annular

ducting surrounding the lower hull ,Which generate electromagnetic fields .


Pod mount type —Two pods of thrusters are installed at both sides of the lower hull of a

SWATH Type ship .Their configuration is similar to a inner Ducting type thruster.


YAMATO 1

"YAMATO 1" is the first superconducting electro-magneto hydrodynamic (MHD)

propulsion ship in the world. This ship was developed by Mitsubishi Corporation. The ship was

designed to be propelled by directly using magneto hydrodynamic force generated by sending

electric current through a magnetic field created in seawater by superconducting magnets.

"YAMATO 1" is a ship built for the purpose of verifying possibilities of actualizing

superconducting MHD propulsion ships. A committee named Super conducting MHD

Propulsion Ship R&D Committee was organized by the Ship & Ocean Foundation and had and

operation as compared with conventional propulsion systems...


GENERAL ARRANGEMENT OF YOMATO 1

In place of a propeller or paddle wheel, Yamato 1 uses jets of water produced by a magneto hydrodynamic (MHD) propulsion system. Inside each thruster, the seawater flows into six identical tubes, arranged in a circle like a cluster of rocket engines. The ten inch diameter tubes are individually wrapped in saddle shaped superconducting magnetic coils made of niobium titanium alloy filaments packed into wires with copper cores and shells. Liquid helium cools the coils to –452.13°F, just a few degrees above absolute zero, keeping them in a superconducting state in which they have almost no resistance to electricity. Electricity flowing through the coils generates powerful magnetic fields within the thruster tubes. When an electric current is passed between a pair of electrodes inside each tube, seawater is forcefully ejected from the tubes, jetting the [craft] forward.


Upper View


Longitudinal View


Propulsion System


Outline of propulsion system


The propulsion systems are composed of superconducting magnets, persistent current switches,

helium refrigerator units, seawater pipes electrodes, etc. and each one set of these systems is

arranged on the port and starboard sides of the ship respectively. The superconducting magnets

are of a six-linked ring construction with six saddle type superconducting coils being arranged on

a concentric circle in a helium vessel. The leakage of magnetic field around magnets are made

small as much as possible by mutually combining magnetic fluxes of each coil. The seawater

pipes are blow passages of seawater through the hull and are subjected to seawater pressure and

electromagnetic force. Furthermore, the seawater pipes are required to be with a good insulating

character against electricity in order to hold electrodes and bus bars for sending electric current.

For these reasons, the seawater pipes are made of epoxy resin GFRP.

Outline of shore support base

Because the superconducting magnets are to be operated in a persistent

current mode during navigation, no facilities are required onboard for initial

cooling of

the superconducting MHD propulsion system from room temperature to the

liquid helium temperature and for magnetization and demagnetization.

Therefore, these facilities are installed ashore and it has been planned to

reduce the weight of "YAMATO 1'' and to simplify the propu1sion system

onboard.


Advantages

The thruster contains no moving part in propulsion system

It works on MHD technology

It can be used for making ships and sub marines

It is pollution free

It produces no noise ,so it is used for warfare


Conclusion


hydrodynamic force generated by sending electric current through a magnetic field created in sea

water by superconducting magnets. When electric current is sent to sea water at right angles to

the magnetic field, and electromagnetic force (Lorentz force) acts on sea water in the direction

perpendicular to both the direction of magnetic field and that of electric current. Propulsion force

is gained as a reaction force of this Lorentz force.MHD propulsion is very advantageous as

it consists of no moving parts and it is pollution free. In the near future this propulsion device

will be used over the conventional propulsion devices.

mhd propulsion thruster (2)

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