Alternating current liquid metal vortex magnetohydrodynamic generator

•A novel liquid metal MHD generator with easily tunable voltage output is proposed.•Pulsating current output is produced using an integrated liquid metal switch.•Developed analytical models for flow, voltage, and current agree well with results.•System has the potential to generate power output of the order of a watt. A proof of principle for a new mechanical to electrical energy harvesting method using an AC liquid metal vortex magnetohydrodynamic (MHD) generator has been designed, fabricated, demonstrated, and analyzed. The novel energy harvesting approach uses mechanical force to drive a swirling flow of Galinstan through a cylindrical chamber in the presence of a strong magnetic field. Useful voltage is produced via an integrated liquid switch that causes the internal resistance of the generator to vary in time, leading to a pulsating current that is transformed to higher voltage. An analytical model for the system was developed and validated against experimental results taken with multiple load resistances and transformer windings. The AC generator is capable of delivering power of the order of one watt and voltages of the order of one volt in a compact and versatile package, and it shows substantial promise for previously unaccessible energy harvesting applications including mobile electronics, prosthetics, and industrial machinery. Thus, this generation method would allow for high power density at size and velocity scales where that previously would have been untenable.