MAGNETOHYDRODYNAMIC 

 PROPULSION FOR SEA VEHICLES 



E. L. Resler, Jr. 

 Cornell University .: ■ 



Ithaca, New York ■ ... 



Any propulsion mechanism, internal or external to the vehicle structure, 

 is ultimately a pump that imparts momentum to the fluid medium in the direc- 

 tion opposite the vehicle's direction of motion. The thrust on the vehicle is the 

 reaction force and is equal and opposite the force on the fluid. For magneto- 

 hydrodynamic (MHD) type propulsion, the general features are the same; how- 

 ever, some of the reaction forces may act via the electromagnetic fields on 

 magnetic pole pieces or current elements producing the magnetic field. Al- 

 though many different arrangements are possible, the general features of such 

 propulsion systems are most easily discussed and examined for a simple duct 

 flow with constant area. 



Consider a simple propulsive duct or MHD-type pump, as depicted in Fig. 

 1. This type of pump is usually referred to as a crossed fields pump, as the 

 electric and magnetic fields are at right angles to one another. The details of 

 the sources of the electromagnetic fields will not be discussed, but our purpose 

 is to explore their interaction with the fluid in the propulsive duct. 



TZZZZZZZZZ 



S=DUCT 

 DIA 



/7NB = MAGNETIC FIELD 



U - FLUID VELOCITY 



^ 



V=VOLTAGE 



Sp = ELECTRODE AREA 



I = CURRENT 



Fig. 1 - MHD propulsive duct, B field towards 

 the reader 



In this discussion we will neglect the internal resistance of the source of 

 current I, and the fluid in the duct will have a conductivity . The resistance 

 the fluid offers to the current flow in Fig. 1 is then R = h / Se. The applied 



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