Resler 



COIL WINDING 



Fig. 5 - Use of sea water as the "ring" of 

 Fig. 4 



the water move together. This combination makes use of the good coupling, 

 because of the high electrical conductivity of the liquid metal, and retains the 

 general features of MHD propulsion. 



Note that these electromagnetic devices work successfully, in that the 

 currents flow in such a manner as to realize the magnetic pressure as a fluid 

 pressure. We have discussed above mostly dynamic systems. Magnetic pres- 

 sure can be realized in yet another manner. It is possible to fabricate a fluid 

 with ferromagnetic properties by suspending very small ferromagnetic parti- 

 cles, say magnetite, in a fluid such as kerosene. These fluids tend to deform 

 with the magnetic fields, much as conducting fluids. This is another way that 

 magnetic pressure can be materialized in a fluid. Such a ferromagnetic fluid 

 can be used in the device shown schematically in Fig. 5, and would replace the 

 liquid metal. This fluid would also be more compatible with sea operations. 

 A number of papers that describe such a fluid appear in the bibliography that 

 follows. The theory outlined at the outset is not directly applicable to ferro- 

 magnetic fluids, but the phenomena are similar to those described. 



A brief presentation of the principles governing direct magnetohydro- 

 dynamic propulsion has been discussed and typical operating conditions out- 

 lined. Other indirect schemes, seemingly more convenient, have also been 

 discussed. It seems fair to conclude that the versatility of MHD propulsion 

 makes worthwhile the further exploration of its possibilities. 



BIBLIOGRAPHY 



Way, S., and Devlin, C, Prospects for the electromagnetic submarine. AIAA 

 3rd Propulsion Joint Specialist Conference, AIAA Paper 67-432, July 17-21, 

 1967 ,,, :. 



Resler, E.L., Jr., and Rosensweig, R.E., Magnetocaloric power. AIAA Journal 

 2 (No. 8) pp. 1418-1422, (1964) 



Rosensweig, R.E., Magnetic fluids. Int. Sci. Technol., pp. 48-57, July 1966 



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