scholarly journals WAVE ENERGY CONVERTER WITH WAVE ABSORBING CONTROL

2018 ◽  
pp. 61
Author(s):  
Takashi Kawaguchi ◽  
Kunio Nakano ◽  
Shogo Miyajima ◽  
Taro Arikawa
Keyword(s):  
Electric Power ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Tank Wall ◽  
Energy Converter ◽  
Reflected Waves ◽  
Wave Sensors ◽  
Incident Waves ◽  
The Waves

The wave absorbing control using wave sensors was theorized and developed by the authors, about 30 years ago. It was originally for absorbing wavemakers for tank tests in laboratories. This control enables wavemakers to generate the desired incident waves while absorbing undesirable reflected waves from the tank wall. When waves are absorbed by the wavemaker, the energy of the waves are also absorbed, that is, the energy is regenerated to electric power with the wavemaker drivemotor. According to this theory, in case that certain waves are generated by an oscillating body, these waves can be absorbed by the same body. Therefore, we can design a wave energy converter as a kind of absorbing wavemaker.

scholarly journals A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

2021 ◽  
Author(s):  
Michele Righi ◽  
Giacomo Moretti ◽  
David Forehand ◽  
Lorenzo Agostini ◽  
Rocco Vertechy ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Deformations ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Pressure Differential ◽  
Design Stage ◽  
Small Scale ◽  
Energy Converter ◽  
Wide Range ◽  
The Waves

AbstractDielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable promise in replacing expensive and inefficient power take-off systems with cheap direct-drive generators. This paper introduces a concept of a pressure differential wave energy converter, equipped with a DEG power take-off operating in direct contact with sea water. The device consists of a closed submerged air chamber, with a fluid-directing duct and a deformable DEG power take-off mounted on its top surface. The DEG is cyclically deformed by wave-induced pressure, thus acting both as the power take-off and as a deformable interface with the waves. This layout allows the partial balancing of the stiffness due to the DEG’s elasticity with the negative hydrostatic stiffness contribution associated with the displacement of the water column on top of the DEG. This feature makes it possible to design devices in which the DEG exhibits large deformations over a wide range of excitation frequencies, potentially achieving large power capture in a wide range of sea states. We propose a modelling approach for the system that relies on potential-flow theory and electroelasticity theory. This model makes it possible to predict the system dynamic response in different operational conditions and it is computationally efficient to perform iterative and repeated simulations, which are required at the design stage of a new WEC. We performed tests on a small-scale prototype in a wave tank with the aim of investigating the fluid–structure interaction between the DEG membrane and the waves in dynamical conditions and validating the numerical model. The experimental results proved that the device exhibits large deformations of the DEG power take-off over a broad range of monochromatic and panchromatic sea states. The proposed model demonstrates good agreement with the experimental data, hence proving its suitability and effectiveness as a design and prediction tool.

scholarly journals Resonant behaviour of an oscillating wave energy converter in a channel

2012 ◽  
Vol 701 ◽  
pp. 482-510 ◽  
Author(s):  
Emiliano Renzi ◽  
F. Dias
Keyword(s):  
Wave Energy ◽  
Velocity Potential ◽  
Wave Energy Converter ◽  
Maximum Efficiency ◽  
Hypersingular Integral Equation ◽  
Energy Converter ◽  
Theory Application ◽  
Incident Waves ◽  
Resonant Mechanism ◽  
Recent Laboratory

AbstractA mathematical model is developed to study the behaviour of an oscillating wave energy converter in a channel. During recent laboratory tests in a wave tank, peaks in the hydrodynamic actions on the converter occurred at certain frequencies of the incident waves. This resonant mechanism is known to be generated by the transverse sloshing modes of the channel. Here the influence of the channel sloshing modes on the performance of the device is further investigated. Within the framework of a linear inviscid potential-flow theory, application of Green’s theorem yields a hypersingular integral equation for the velocity potential in the fluid domain. The solution is found in terms of a fast-converging series of Chebyshev polynomials of the second kind. The physical behaviour of the system is then analysed, showing sensitivity of the resonant sloshing modes to the geometry of the device, which concurs in increasing the maximum efficiency. Analytical results are validated with available numerical and experimental data.

scholarly journals Numerical Study on the Optimization of Hydrodynamic Performance of Oscillating Buoy Wave Energy Converter

2021 ◽  
Vol 28 (1) ◽  
pp. 48-58
Author(s):  
Wenbin Lai ◽  
Yonghe Xie ◽  
Detang Li
Keyword(s):  
Wave Energy ◽  
Numerical Study ◽  
Energy Conversion Efficiency ◽  
Absorption Efficiency ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Energy Converter ◽  
Physical Experiments ◽  
Working Principle ◽  
The Waves

Abstract The oscillating buoy wave energy converter (OBWEC) captures wave energy through the undulating movement of the buoy in the waves. In the process of capturing wave energy, the hydrodynamic performance of the buoy plays an important role. This paper designed the “Haida No. 1” OBWEC, in which the buoy adopts a form of swinging motion. In order to further improve the hydrodynamic performance of the buoy, a 2D numerical wave tank (NWT) model is established using ADINA software based on the working principle of the device. According to the motion equation of the buoy in the waves, the influence of the buoy shape, arm length, tilt angle, buoy draft, buoy width, wave height and Power Take-off (PTO) damping on the hydrodynamic performance of the buoy is studied. Finally, a series of physical experiments are performed on the device in a laboratory pool. The experimental results verify the consistency of the numerical results. The research results indicate that the energy conversion efficiency of the device can be improved by optimizing the hydrodynamic performance of the buoy. However, the absorption efficiency of a single buoy for wave energy is limited, so it is very difficult to achieve full absorption of wave energy.

scholarly journals KNSwing—On the Mooring Loads of a Ship-Like Wave Energy Converter

2019 ◽  
Vol 7 (2) ◽  
pp. 29
Author(s):  
Kim Nielsen ◽  
Jonas Thomsen
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Numerical Models ◽  
Breaking Waves ◽  
Wave Energy Converter ◽  
Experimental Results ◽  
Irregular Waves ◽  
Mooring System ◽  
Energy Converter ◽  
The Waves

The critical function of keeping a floating Wave Energy Converter in position is done by a mooring system. Several WECs have been lost due to failed moorings, indicating that extreme loads, reliability and durability are very important aspects. An understanding of the interaction between the WEC’s motion in large waves and the maximum mooring loads can be gained by investigating the system at model scale supported by numerical models. This paper describes the testing of a novel attenuator WEC design called KNSwing. It is shaped like a ship facing the waves with its bow, which results in low mooring loads and small motions in most wave conditions when the structure is longer than the waves. The concept is tested using an experimental model at scale 1:80 in regular and irregular waves, moored using rubber bands to simulate synthetic moorings. The experimental results are compared to numerical simulations done using the OrcaFlex software. The experimental results show that the WEC and the mooring system survives well, even under extreme and breaking waves. The numerical model coefficient concerning the nonlinear drag term for the surge motion is validated using decay tests. The numerical results compare well to the experiments and, thereby, the numerical model can be further used to optimize the mooring system.

scholarly journals Analytical Study on an Oscillating Buoy Wave Energy Converter Integrated into a Fixed Box-Type Breakwater

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Xuanlie Zhao ◽  
Dezhi Ning ◽  
Chongwei Zhang ◽  
Yingyi Liu ◽  
Haigui Kang
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Maximum Efficiency ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Linear Potential ◽  
Energy Converter ◽  
Transmission Coefficients ◽  
Incident Waves

An oscillating buoy wave energy converter (WEC) integrated to an existing box-type breakwater is introduced in this study. The buoy is installed on the existing breakwater and designed to be much smaller than the breakwater in scale, aiming to reduce the construction cost of the WEC. The oscillating buoy works as a heave-type WEC in front of the breakwater towards the incident waves. A power take-off (PTO) system is installed on the topside of the breakwater to harvest the kinetic energy (in heave mode) of the floating buoy. The hydrodynamic performance of this system is studied analytically based on linear potential-flow theory. Effects of the geometrical parameters on the reflection and transmission coefficients and the capture width ratio (CWR) of the system are investigated. Results show that the maximum efficiency of the energy extraction can reach 80% or even higher. Compared with the isolated box-type breakwater, the reflection coefficient can be effectively decreased by using this oscillating buoy WEC, with unchanged transmission coefficient. Thus, the possibility of capturing the wave energy with the oscillating buoy WEC integrated into breakwaters is shown.

scholarly journals Optimization of an Invention Based on a Force Multiplier Mechanism for Wave Power Generation

2014 ◽  
Vol 507 ◽  
pp. 480-485
Author(s):  
Javier Aparisi ◽  
Jose González ◽  
Bernabé Hernandis
Keyword(s):  
Power Generation ◽  
Wave Height ◽  
Wave Energy ◽  
Fossil Fuels ◽  
Clean Energy ◽  
Wave Energy Converter ◽  
Wave Power ◽  
Rectilinear Motion ◽  
Energy Converter ◽  
The Waves

The development and exploitation of new sources of clean energy that do not depend on traditional sources based on the use of fossil fuels, is the focus of this research, which starts with the optimization of an invention capable of transforming a reciprocating rectilinear motion into continuous circular motion in a very efficient way, to be used in the development of a Wave Energy Converter (WEC), capable of operating with low wave height and taking advantage of the oscillating movement of the waves both when rising, and when lowering, unlike other similar devices that harness it only in one way.

NUMERICAL MODELLING AND ASSESSMENT OF THE UGEN FLOATING WAVE ENERGY CONVERTER

2021 ◽  
Vol 153 (A2) ◽  
Author(s):  
N Fonseca ◽  
S R Silva ◽  
J Pessoa
Keyword(s):  
Numerical Modelling ◽  
Relative Motion ◽  
Wave Energy ◽  
Hydrodynamic Model ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Rolling Mode ◽  
The Waves

The paper presents a linear hydrodynamic model for the UGEN wave energy converter, an analysis of the dynamics of the system and the predicted ability to extract energy from the waves. The UGEN (floating device with a U tank for GENeration of electricity from waves) consists of an asymmetric floater with a large internal U tank filled with water, where the energy is extracted from the relative motion between the water inside the tank and the rolling of the floater. The floater rolling mode of motion is the main stimulator of the motion of the water in the tank, however the sway and heave motions are also coupled therefore the system has motion.

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