Sea-water magnetohydrodynamic propulsion for next-generation undersea vehicles. Annual report, 1 February 1989-31 January 1990

Three tasks were performed in this report period. Their individual abstracts are summarized as follows: (I) Thruster Performance Modelings - The purpose of this work is to analyze underwater vehicle propulsion by applying Lorentz forces to the surrounding sea water. While this propulsion concept involves two different schemes, i.e. the external field method and the internal duct-type method, the current analysis focuses on the internal thruster scheme due to the space limitations and speed considerations. The theories of magnetohydrodynamic (MHD) pump jet propulsion are discussed. A so-called dual control volume analysis to model the MHD thruster, and calculations of vehicle velocity and power efficiency are presented. (II) Sea Water Conductivity Enhancement - This work discusses the mechanisms of enhancing the electric conductivity of sea water. The direct impact of conductivity enhancement of sea water is the improvement of propulsion performances of marine vehicles that use the magnetohydrodynamic thrusts of sea water. The performance improvement can be in energy efficiency or in vehicle speed. Injection of strong electrolytes (acids or bases) into the main sea water flow in the MHD channel appeared to be the most logical way of achieving the purpose. (III) Status of Current Superconductivity Works - A surveymore » of recent research in both low -T{sub c} and high -T{sub c} superconductivities is provided. It is generally true that high -T{sub c} superconductors carry critical current densities several orders of magnitude less than those of low -T{sub c} ones.« less