MAGNETO HYDRODYNAMIC PROPULSION
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 seminar class Active In SP Posts: 5,361 Joined: Feb 2011 02-03-2011, 03:56 PM Submitted by AKHIL K DAS   RAJIV GANDHI INSTITUTE OF TECHNOLOGY.ppt (Size: 521.5 KB / Downloads: 213) introduction  The magnetohydrodynamic propulsion is a new propulsion system which is used for propelling ships & submarines.  The magnetohydrodynamic, or MHD, propulsion has no moving parts like propeller, gear, shafts etc  Submarines fitted with it , cannot be detected easily (as it is silent) History  First proposed by W A Rice in 60’s in USA  He does experimental work on it using dc direct drive propulsion using battery driven magnets  Speed 1.5 knots against design goal was 1  Earlier research faded as efficiency achieved was marginal using available magnetic technologies  In 70’s research started using supermagnets in Japan Principle  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 hull  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) J is a current density vector of infinitesiml volume dv B is a magnetic flux density vector  When J and B are constant over the entirevolume V (m3) F = J X B X V (N) Case study- “YAMANTO 1” Mhd ship  The first prototype based on mhd technology was ‘YAMANTO 1’  Made by mistubushi in 1990,weighing 184 tons, traveled at 15 km/hr  It uses a 4 tesla superconducting magnet  Electrodes are titanium with anode coating of DSA & cathode plated with platinum.  Electrode length 3.4m  Superconducting magnets are operated in persistent current mode during navigation  No onboard facilities for initial cooling  It had a shore support base  Initial Cooling,Magnetization & demagnetization are done there  It reduced the weight Cooling method  Cooling of superconducting coil from room temperature to about 20K is done by passing G He  Cooling from 20K-4K is done by using L He filling  L He filling was done by connecting L He reservoir to the L He filling port of the large He refrigerator on shore. Magnetization & de magnetization  The persistent current switch (PCS) is of a thermal type ,turns OFF position when sending current and to the ON position when stop sending current to the PCS heater  For magnetization, the PCS is to be set at the OFF position  PCS is to be switched to the ON position when the current has reached the predetermined value Thrust performance  It is found by Bollard test  Ship moored to a quay by mooring lines fitted with tension meters.  electric current was sent between the electrodes and the generated pull force and pressure in the thruster duct were measured Test results From graph  Bollard pull force , Lorentz force and thrust force increase proportionally to increase of electrode current.  Texp is greater than Tcal  This is due to experimental error  Otherwise measured results agree with calculation Advantages  It has no moving parts (no motors, gears ,shafts) - QUIET OPERATION  high speed due to the absence of a cavitation limit  high efficiency due to the nearly direct conversion of electrical energy into KE  Less demand for fuel Disadvantages  These systems use high magnetic fields, which require the use of cryogenically cooled superconducting coils –increases cost  'Acoustic Signature' –electrolysis off sea water produces visible wake  Magnetic signature Future scope  MHD ships & Subs has a great future because of its silent and high speed performance  For its development more research on superconducting magnets and its subsystems are necessary