Propulsive Efficiencies of Magnetohydrodynamic Submerged Vehicular Propulsors

Magnetohydrodynamic MHD ship propulsion is the process of propelling a vehicular structure by a seawater electromagnetic pump. This propulsion system can be applied to a surface ship or a submerged vehicle however, in this work only submerged vehicles at depths where wave effects can be neglected were considered. Although a number of different arrangements for a MHD propulsion system are possible, the general characteristics of such systems are most easily determined by a simple, ideal MHD rectangular duct of constant cross-sectional area. A mathematical model was developed for calculating the propulsive efficiencies of such a rectangular duct propelling a submerged vehicle. Numerical propulsive efficiencies are presented in terms of many different parameters. Assumptions were generally made in the model that tend to maximize the propulsive efficiency of the MHD system. Thus, the propulsive efficiencies calculated from the model overestimate the efficiencies of the corresponding real MHD propulsion system. These numerical results can be used for engineering estimates of the propulsive efficiencies of real MHD propulsion systems.