AC Maritime Magnetohydrodynamic Engine—Resonant Drive Topologies, Propulsion Mechanism, and Experimental Validation

A magnetohydrodynamic (MHD) engine is a propulsion system that converts electric energy into fluid flow by utilizing the Lorentz force. It has the potential to electrify the conventional rotational propellers on ships, which can have adverse effects on the underwater environment. However, the development of an MHD engine for maritime propulsion is sparse, from the motion theory to the prototype investigation. In this article, the advantage of high-frequency ac operation is depicted. The systematic introduction for the ac MHD engine is elucidated for the electromagnetic field generator configurations, engine drive topologies, and onboard compartment distributions. The propulsion mechanism will be interpreted in force analysis, regarding the Lorentz force and its interaction with the fluid by applying the Stokes law, by deriving the forces to a single ion to the liquid dragged by the engine. Moreover, it provides a case study of the practical development for the engine, showing the power circuit with the forward/reverse control, the analysis of the reluctance circuit and magnetic simulation for the magnetic field estimation, and the laboratory testing solution for mock seawater. A 250-W experiment combining the electric and fluid measurements was conducted to benchmark the ac operational MHD engine structure, validating the proposed topology with practical control and presenting 80% accuracy of the propulsion mechanism analysis.