Device for electro-magnetohydrodynamic (EMHD) energy harvesting

摘要

This paper describes a device that uses flow-induced electromagnetic induction as a source of continuous electrical power. The target application is energy harvesting (auxiliary power) for unmanned undersea vehicle (UUV) intelligence, reconnaissance, surveillance (ISR) operations to extend mission duration (trickle charging) or to power supplementary sensor systems. Other military/commercial applications can be envisioned as well for any system that involves the flow of low conductivity fluids and a need for low-level continuous electrical power. The basic device consists of orthogonal pairs of electrodes and a permanent magnet mounted flush with the vehicle surface. When a conducting fluid (e.g., seawater) flows over the device, an electric field is established in the fluid resulting from the motion of the conducting fluid through the magnetic field. The mean flow induced electric field in the fluid is mapped to a DC voltage across the electrode pairs by the same physical process exploited in electromagnetic flow meters. The theoretical basis for the device operation is developed here and used to determine the optimum device/array configuration and to provide numerical estimates of the available DC power. For a UUV at an operating speed of 10 knots, it is estimated that a continuous DC power level of 10mW can be obtained by a relatively compact array of these devices. Laboratory experiments and a more complete analytical model are required to develop an operational system for a full-scale UUV.