Energy harvesting system using flow-induced vibrations

System harnesses fluid flow to induce vibrations that are converted to electrical energy

Energy Environmental

The kinetic energy harvesting system

Renewable sources of energy such as solar, wind, and waves have been long sought after. Improved harvesting systems for these sources are continually being developed, and are especially favored for ocean-based environments.

Renewable sources of energy such as geothermal, sediment, or ocean current conditions must be utilized in submerged devices, where surface-based devices are not applicable. These methods leave a need for a dependable and compact system to provide a renewable power source for underwater systems.

This system developed by the Navy harnesses fluid flow to induce vibrations that are converted to electrical energy. The system consists of a housing, vibrating components, and a kinetic energy harvester (KEH) made up of coils and magnets.

The housing is shaped to direct fluid flow through the system. One example of a housing shape is a hollow cylinder. Ends of vibrating components are attached to a support structure positioned within the hollow cylinder in the path of fluid flow. The other ends of the vibrating components are attached to KEH components located in the walls of the cylinder.

Fluid flow through the system vibrates the support structure and components, which in turn induces an electric current in the KEH. If flow-induced oscillations reach the resonance frequency of the KEH, a maximum amount of vibration will occur, and the energy output will be constant. Tests have shown that vibrating components in a small device (13mm diameter cylinder) in a low fluid speed (2 knots) can achieve oscillations at the resonance frequency of the KEH (10 Hz).

Multiple systems may be combined in a single housing to not only increase energy production but to create patterns that take advantage of flow instabilities created by neighboring systems. With the versatility of device applications, an external system may connect directly to the KEH as a power supply where energy is not otherwise accessible.

The KEH may find application in any location with water-based or air-based fluid flow and in particular as renewable power for underwater systems and sensors.

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