External MHD propulsion

D. Convert - J. P. Thibault

Laboratoire des Ecoulements Geophysiques et Industriels, Institut de Mecanique de Grenoble (LEGI IMG), CNRS-UJF-INPG, B.P. 53 X. 38041 Grenoble cedex, France

Abstract
External magnetohydrodynamic propulsion presents, if high induction is achieved, a strong coupling between electromagnetism a nd fluid mechanics. It is shown that this coupling concerns the electrical field and the velocity. The turbulent flow, at constant pressure, does not affect the magnetic field. A momentum balance links the evolution of the momentum thickness to the thrust of the propeller. At first stage, it appears that the flow and the electromagnetic variables are bidimensional. Two models, in different planes, treat the two problems and their connection. They are applied to a submarine and predict an overall efficiency of 44% at 8 m/s, with current and tension comparable to the ones of the inner dc propulsion mode.