Hydrokinetic energy harvesting using tethered undersea kites

2015 ◽  
Vol 7 (4) ◽  
pp. 043114 ◽  
Author(s):  
David J. Olinger ◽  
Yao Wang
Keyword(s):  
Energy Harvesting ◽  
Hydrokinetic Energy

Toward a Contactless Hydrokinetic Energy Harvester: A Computational Magnetic Field Estimation

2018 ◽  
Author(s):  
Georgios Tsakyridis ◽  
Nikolaos I. Xiros ◽  
Michael M. Bernitsas
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Attitude Control ◽  
Magnetic Levitation ◽  
Magnetic Energy ◽  
Hydrodynamic Drag ◽  
Core Element ◽  
Hydrokinetic Energy ◽  
Ferromagnetic Core ◽  
The Magnetic Field

Magnetic levitation (maglev) concepts are applied to a variety of industries such as the automotive, aerospace, or energy in order to accomplish different tasks: suspension and propulsion in maglev trains, rocket propulsion and spacecraft attitude control, centrifuge of nuclear reactors. In this paper, maglev is implemented in environmentally friendly hydrokinetic energy harvesting to achieve contactless bearing, thus, minimizing friction and improving efficiency. Generally, maglev systems exhibit higher efficiency and reduced maintenance while providing longer lifetime and higher durability when appropriate engineering design and control are applied. A Flow Induced Oscillation (FIO) energy-harvesting converter is considered in this work. To minimize friction in the support of the cylinder in FIO (vortex induced vibrations and galloping) due to high hydrodynamic drag, a maglev system is proposed. In the proposed configuration, a ferromagnetic core (element 1), of known dimensions, is considered under the effects of an externally imposed magnetic field. A second ferromagnetic element, of smaller dimensions, is then placed adjacent to the previous considered core. This particular configuration results in a non-homogenous magnetic field for element 1, caused by dimensional disparity. Specifically, the magnetic flux does not follow a linear path from the ferromagnetic core to element 2. A general electromagnetic analysis is conducted to derive an analytical form for the magnetic field of element 1. Subsequent numerical simulation validates the obtained formula. This distinct expression for the magnetic field is valuable towards calculating the magnetic energy of this specific configuration, which is essential to the design of the FIO energy harvesting converter considered in this work.

Hydrokinetic Energy Harvesting System From Vortex Induced Vibrations of Submerged Bodies

2011 ◽  
Author(s):  
Varun Lobo ◽  
Arindam Banerjee ◽  
Nyuykighan Mainsah ◽  
Jonathan Kimball
Keyword(s):  
Boundary Layer ◽  
Energy Harvesting ◽  
Vortex Shedding ◽  
Computational Study ◽  
High Energy ◽  
Power Converter ◽  
Design Parameters ◽  
Hydrokinetic Energy ◽  
Energy Harvesting System ◽  
Efficient Power

A Vortex Induced Vibration (VIV) based hydrokinetic energy system is discussed in this paper. Vibrations induced on a body (facing an external flow) due to the periodic irregularities in the flow caused by boundary layer separation are called as VIV. This separation of the boundary layer from the surface causes vortex formation in the wake region of the cylinder. The lift-force or the transverse oscillation of the vibrating cylinder depends upon the strength and modes of the vortex formed. The VIV energy harvesting system is based on the idea of maximizing rather than spoiling vortex shedding and was discovered in 2004 at the University of Michigan by Bernitsas and Raghavan. The vibrating bodies will in turn be used to harness energy using an efficient power-take-off system. In this paper, we discuss the hydrodynamic design of such a VIV based energy harvesting system using computational fluid dynamics. A fluid structure interaction calculation is performed to determine the forces on the surface of a bluff body due to separation of vortices from the surface. The hydrodynamic forces that act on such a system depend on the cylinder diameter, flow velocity, modes of vortex shedding and arrangement of cylinder(s). A detailed computational study on the effect of different design parameters listed above are first carried on a single cylinder arrangement; this is followed by a more detailed analysis that is extended to multiple cylinders. For a two-cylinder arrangement, the positions in which the cylinders are placed are also found to play an important role, as the vortex shed from one cylinder may be used to enhance the forces of lift on another cylinder present in its wake. Furthermore, the design of a VIV generator requires optimal damping and low mass ratio to enable high energy conversion via an efficient power take-off mechanism. The working and design considerations of the energy converter is outlined starting with a set of basic definitions pertaining to this technology. A tubular linear interior permanent magnet generator (TL-IPM) connected to a power converter is used; a linear generator was chosen to minimize mechanical components, such as gears or cams in the system.

Marine hydrokinetic energy harvesting performance of diamond and square oscillators in tandem arrangements

Energy ◽  
2020 ◽  
Vol 202 ◽  
pp. 117749 ◽  
Author(s):  
V. Tamimi ◽  
M.J. Esfehani ◽  
M. Zeinoddini ◽  
S.T.O. Naeeni ◽  
J. Wu ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Hydrokinetic Energy ◽  
Marine Hydrokinetic

scholarly journals Influence of attack angle on vortex-induced vibration and energy harvesting of two cylinders in side-by-side arrangement

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882259
Author(s):  
Li Zhang ◽  
Xinru Mao ◽  
Lin Ding
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Energy Conversion Efficiency ◽  
Maximum Energy ◽  
Attack Angle ◽  
Navier Stokes ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Wake Patterns ◽  
Vibration Responses

The vortex-induced vibration and energy harvesting of two cylinders in side-by-side arrangement with different attack angles are numerically investigated using two-dimensional unsteady Reynolds-Averaged Navier–Stokes simulations. The Reynolds number ranges from 1000 to 10,000, and the attack angle of free flow is varied from 0° to 90°. Results indicate that the vortex-induced vibration responses with attack angle range of 0°≤  α ≤ 30° are stronger than other attack angle cases. The parallel vortex streets are clearly observed with synchronized vortex shedding. Relatively large attack angle leads to a phase difference between the wake patterns of the two cylinders. Hydrokinetic energy can be obviously harvested when Re > 4000. Compared with the larger attack angle case, the two side-by-side cylinders with smaller attack angle have better performance on energy conversion. The maximum energy conversion efficiency of 21.7% is achieved. The optimum region for energy conversion is 5000 ≤  Re ≤ 7000 and 0°≤  α ≤ 30°.

Piezoelectric Artificial Kelp for Energy Harvesting

2010 ◽  
Author(s):  
Alexander M. Pankonien ◽  
Zoubeida Ounaies
Keyword(s):  
Energy Harvesting ◽  
Piezoelectric Material ◽  
Piezoelectric Materials ◽  
Kelp Forests ◽  
Flow Conditions ◽  
Marine Habitat ◽  
Specific Flow ◽  
Hydrokinetic Energy ◽  
Piezoelectric Energy ◽  
Energy Harvesting System

This study focuses on a hydrokinetic energy harvesting system concept using piezoelectric materials. The Piezoelectric Active Kelp (PAK) system will consist of chemically inert piezoelectric polymers or piezoelectric ceramics manufactured into long flexible ribbons. The PAK system will convert the natural mechanical motions seen in kelp forests due to oceanic wave action, into electricity. As the periodic ocean currents, resulting from waves, pass over the PAK system, they cause the structure to oscillate back and forth. The piezoelectric materials will convert this mechanical motion directly into electrical power via the inverse piezoelectric effect. Large numbers of piezo-kelp ribbons would be mounted like forests on the ocean floor, producing a constant stream of smart grid power. PAK forest systems would also provide an artificial marine habitat while meeting the world’s demand for inexpensive and sustainable energy. Contrary to most forms of hydrokinetic energy harvesting system, the PAK system has no fast-moving parts or turbines and will be made of environmentally inert materials. The amount of power harvested by the PAK system depends upon the flow conditions, device configuration and size, and its piezoelectric material properties. Assuming specific flow conditions and fluid-structure interaction, this study will determine the optimal piezoelectric material to use, along with physical dimensions and layup configuration, to maximize the volumetric power density of the PAK system. The power generated by three common piezoelectric energy harvesting configurations: the unimorph, a homogeneous bimorph and a heterogeneous bimorph, will be compared for both a piezopolymer and a piezoceramic. Additionally, an appropriate figure-of-merit is also identified, based on the piezoelectric coefficient product (d31· g31) to compare the power production capabilities across materials.

Energy Harvesting From the Tidal Currents Using a Mangrove-Like System

2020 ◽  
Author(s):  
Amirkhosro Kazemi ◽  
Oscar Curet ◽  
Daniel Gómez ◽  
Eduardo E. Castillo
Keyword(s):  
Energy Harvesting ◽  
High Speed ◽  
Oscillation Amplitude ◽  
Tidal Energy ◽  
Tidal Currents ◽  
Electric Generator ◽  
Hydrokinetic Energy ◽  
Energy Devices ◽  
Novel Device ◽  
Mangrove Roots

Abstract Tidal energy has the potential for future electricity generation to be widely used in intercostal areas during the rise and fall of tides. Inspired by mangrove roots, we designed a novel device to harvest hydrokinetic energy from tidal currents. This device consists an oscillating cylinder, partially submerged in a flow of water and an electric generator composed of a fixed magnet and a coil attached to the cylinder pivoted at its top by a thin flexible steel plate. This energy harvesting system is considered as one-degree-of-freedom vortex-induced vibration (VIV). The oscillation amplitude of the cylinder tip was recorded with a high-speed camera and 2-D PIV measurements were made to explore the hydrodynamic interaction within the devices for Reynolds numbers ranging from 200 to 1500 (based on cylinder diameter) consistent with biological velocity in tidal flows. We analyzed the kinematics as well as the power generation of the device for different stiffness of the plate. We observed that the cylinder was unmoved for low water velocities; however, by increasing the flow velocity the oscillations increase and reached a maximum value; similar fashion was observed for all stiffness. It was found that for a specific range of reduced velocity (0 < Ur < 3.5) the device worked in its optimal range in which the amplitude of oscillations and the efficacy of the system reach the highest values. This analysis of VIV correlated with oscillations will be fundamental for future bio-inspired energy harvesting devices. These renewable energy devices could have applications to power small actuators or sensors to monitor coastal infrastructure.

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