Experimental Investigation on Hydrodynamic Effectiveness of a Wave Energy Converter Using Floating Breakwater

2020 ◽  
Author(s):  
Wei Peng ◽  
Junwei Ma
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Resonance State ◽  
Wave Energy Converter ◽  
Scale Model ◽  
Maintenance Cost ◽  
Wave Direction ◽  
Energy Converter ◽  
Floating Structure ◽  
Floating Breakwater

Abstract Wave energy is favored by more and more people because of its wide distribution, pollution-free, renewable and many other advantages. Among numerous wave energy converting devices, the converters using floating breakwaters are recognized to be quite promising as the construction and maintenance cost can be shared. In this study, a shoreline wave energy converter (WEC) is proposed which consists of a floating breakwater arranged along the wave direction and restricted to only have vertical degree of motion. Making use of the motion of breakwaters, a dynamo is able to convert the wave power to electricity. At the same time, the incoming waves can be attenuated due to the complex interaction between waves and the floating structure. A scale model was built in the laboratory at Hohai University, and then employed to investigate the performance of developed wave energy device. In the physical model, dynamos and resistance were employed as the power take-off (PTO) system, and the instantaneous output power could be calculated using the measured data. Experimental results show that the resonance state of float plays an important role for the wave energy extraction, and the hydrodynamic efficiency of the device under the resonance state can be up to 41.8% for single breakwater, counting in the internal energy converted by the dissipative force. When subjected to shorter waves, the PTO damping encourages the wave reflection; whereas, more wave energy is dissipated or transformed to power for longer waves. Meanwhile, the PTO damping is also a negative factor for the wave overtopping reduction as the motion of float may be restrained considerably. Last but not the least, the PTO load is proved to be a significant parameter for the optimization the output power, and a strategy must be found to achieve the best power conversion under the dominant wave conditions.

Novel hydraulic mechanism-based output power regulation for the wave energy converter

2021 ◽  
Vol 110 ◽  
pp. 102587
Author(s):  
Dazhou Geng ◽  
Yang Zheng ◽  
Qijuan Chen ◽  
Xuhui Yue ◽  
Donglin Yan
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Power Regulation ◽  
Hydraulic Mechanism

scholarly journals Deep Learning for Wave Energy Converter Modeling Using Long Short Term Memory

2021 ◽  
Author(s):  
Seyed Milad Mousavi ◽  
Majid Ghasemi ◽  
Mahsa Dehghan Manshadi ◽  
Amir Mosavi
Keyword(s):  
Wind Speed ◽  
Output Power ◽  
Wave Energy ◽  
Short Term Memory ◽  
Ocean Waves ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Short Term ◽  
Term Memory ◽  
Long Short Term Memory

Accurate forecasts of ocean waves energy can not only reduce costs for investment but it is also essential for management and operation of electrical power. This paper presents an innovative approach based on the Long Short Term Memory (LSTM) to predict the power generation of an economical wave energy converter named “Searaser”. The data for analyzing is provided by collecting the experimental data from another study and the exerted data from numerical simulation of searaser. The simulation is done with Flow-3D software which has high capability in analyzing the fluid solid interactions. The lack of relation between wind speed and output power in previous studies needs to be investigated in this field. Therefore, in this study the wind speed and output power are related with a LSTM method. Moreover, it can be inferred that the LSTM Network is able to predict power in terms of height more accurately and faster than the numerical solution in a field of predicting. The network output figures show a great agreement and the root mean square is 0.49 in the mean value related to the accuracy of LSTM method. Furthermore, the mathematical relation between the generated power and wave height was introduced by curve fitting of the power function to the result of LSTM method.

scholarly journals Numerical and Experimental Investigation on a Moonpool-Buoy Wave Energy Converter

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2364 ◽  
Author(s):  
Hengxu Liu ◽  
Feng Yan ◽  
Fengmei Jing ◽  
Jingtao Ao ◽  
Zhaoliang Han ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Scale Model ◽  
Energy Converter ◽  
Point Absorber ◽  
Motion Responses ◽  
Computational Fluid Dynamics Cfd ◽  
The Time Domain ◽  
Good Agreement

This paper introduces a new point-absorber wave energy converter (WEC) with a moonpool buoy—the moonpool platform wave energy converter (MPWEC). The MPWEC structure includes a cylinder buoy and a moonpool buoy and a Power Take-off (PTO) system, where the relative movement between the cylindrical buoy and the moonpool buoy is exploited by the PTO system to generate energy. A 1:10 scale model was physically tested to validate the numerical model and further prove the feasibility of the proposed system. The motion responses of and the power absorbed by the MPWEC studied in the wave tank experiments were also numerically analyzed, with a potential approach in the frequency domain, and a computational fluid dynamics (CFD) code in the time domain. The good agreement between the experimental and the numerical results showed that the present numerical model is accurate enough, and therefore considering only the heave degree of freedom is acceptable to estimate the motion responses and power absorption. The study shows that the MPWEC optimum power extractions is realized over a range of wave frequencies between 1.7 and 2.5 rad/s.

Modeling and Experiment of a Novel Micro Wave Energy Converter

2017 ◽  
Vol 863 ◽  
pp. 175-182
Author(s):  
Yi Ming Zhu ◽  
Zi Rong Luo ◽  
Zhong Yue Lu ◽  
Jian Zhong Shang
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Mechanical Energy ◽  
Vertical Motion ◽  
Electrical Energy ◽  
Wave Energy Converter ◽  
Design Parameters ◽  
Energy Converter ◽  
Drive Power ◽  
Continuous Rotation

This paper proposed a novel micro wave energy converter which can convert irregular wave energy into rotating mechanical energy, then into electrical energy. The device consists of an energy absorption part and an energy conversion part. In details, the blades are installed on the absorber circumferentially and averagely, which are capable of converting the vertical motion of the surface body to continuous rotation of the absorber and leading to a great increase in efficiency. A physical prototype was built to test the performance of the novel generator and optimize the design parameters. In the experiment part, a linear motion electric cylinder was used as the drive power to provide the heaving motion for the device. And the experiment platform was built for modeling a marine environment. Also, a data acquisition program was edited in Labview. Thus, the experiment analyzed the influence of amplitude, frequency, blade angle and resistance value to the output power, and then obtained the optimum parameters combination which can maximize the value of the output power. The result will provide reference for the device’s further application.

A multi-point-absorber wave-energy converter for the stabilization of output power

2018 ◽  
Vol 161 ◽  
pp. 337-349 ◽  
Author(s):  
Hoang-Thinh Do ◽  
Tri-Dung Dang ◽  
Kyoung Kwan Ahn
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Point Absorber

scholarly journals Using Flexible Blades to Improve the Performance of Novel Small-Scale Counter-Rotating Self-Adaptable Wave Energy Converter for Unmanned Marine Equipment

2019 ◽  
Vol 7 (7) ◽  
pp. 223 ◽  
Author(s):  
Sun ◽  
Shang ◽  
Luo ◽  
Lu ◽  
Wu ◽  
...  
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Power Supply ◽  
Simulation Analysis ◽  
Average Power ◽  
Wave Energy Converter ◽  
Small Scale ◽  
Energy Converter ◽  
Experimental Conditions ◽  
Blade Thickness

Unmanned marine equipment has been increasingly developed for open seas. The lack of efficient and reliable power supply is currently one of the bottlenecks restricting the practical application of these devices. In order to provide a viable power supply method for unmanned marine equipment, such as sonic buoys and sea robots, we originally propose a novel small-scale flexible blade wave energy converter (WEC) based on self-adaptable counter-rotating operation mechanism. The flexible blade WEC is designed on the basis of the rigid blade WEC with the caging device. This paper identifies the key factors affecting WEC performance through theoretical analysis. According to the numerical simulation analysis, the output mechanical power of the double-layer absorber is 12.8 W, and the hydraulic efficiency is 36.3%. The results of the verification experiment show that the peak power of WEC is 5.8 W and the average power is 3.2 W. The WEC with 65Mn flexible blade under most experimental conditions has the best performance when the blade thickness is 0.10 mm. The study shows that the new generation WEC can effectively overcome the excessive fluctuation of the output power of the previous generation WEC. The output power curve of the novel WEC is relatively smooth, which is conducive to its smooth operation and subsequent utilization and storage of electrical energy.

scholarly journals Hydro-Elastic Modelling of an Electro-Active Wave Energy Converter

2013 ◽  
Author(s):  
Aurélien Babarit ◽  
Benjamin Gendron ◽  
Jitendra Singh ◽  
Cécile Mélis ◽  
Philippe Jean
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Ocean Basin ◽  
Wave Energy Converter ◽  
Scale Model ◽  
Linear Potential ◽  
Energy Converter ◽  
Outer Flow ◽  
Modal Expansion ◽  
Linear Potential Theory

Since 2009, SBM Offshore has been developing the S3 Wave Energy Converter (S3 WEC). It consists in a long flexible tube made of an Electro-Active Polymer (EAP). Thus, the structural material is also the Power Take Off (PTO). In order to optimize the S3 WEC, a hydro-elastic numerical model able to predict the device dynamic response has been developed. The inner flow, elastic wall deformations and outer flow are taken into account in the model under the following assumptions: Euler equation is used for the inner flow. The flow is also assumed to be uniform. Elastic deformation of the wall tube is linearized. The outer flow is modeled using linear potential theory. These equations have been combined in order to build the numerical model. First, they are solved in the absence of the outer fluid in order to obtain the modes of response of the device. Secondly, the outer fluid is taken into account and the equation of motion is solved by making use of modal expansion. Meanwhile, experimental validation tests were conducted in the ocean basin at Ecole Centrale De Nantes. The scale model is 10m long tube made of EAP. The tube deformations were measured using the electro-active polymer. The model was also equipped with sensors in order to measure the inner pressure. Comparisons of the deformation rate between the numerical model and experimental results show good agreement, provided that the wall damping is calibrated. Eventually, results of a technico-economical parametric study of the dimensions of the device are presented.

Design and Hydrodynamic Performance Testing of One-Base Multi-Buoy Floating Sharp Eagle Wave Energy Converter

2015 ◽  
Vol 1092-1093 ◽  
pp. 152-157
Author(s):  
Zhen Peng Wang ◽  
Ya Ge You ◽  
Ya Qun Zhang ◽  
Song Wei Sheng ◽  
Hong Jun Lin
Keyword(s):  
Wave Energy ◽  
High Efficiency ◽  
Performance Testing ◽  
Clean Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Wave Direction ◽  
Energy Converter ◽  
Working Principle ◽  
Period Wave

Research on wave energy extraction has been conducted in many countries to meet the growing demand for clean energy. To find an efficient and economic way to convert wave energy, an one-base multi-buoy offshore floating Sharp Eagle wave energy converter is designed, consisting of four Eagle head absorbing buoys, one semi-submersible barge, one energy conversion system, buoyancy tanks, underwater appendages and other components. The working principle of the device is described in this paper. To test the hydrodynamic performance of device and make an initial evaluation for the design, a model experiment of 1/13.78th scale was carried out. The influence of wave period, wave height, pressure in hydrocylinders and wave direction is tested. All the efficiencies in different conditions are compared with each other, while the high efficiency and stability of device are verified.

Latching Control of an OWC Spar-Buoy Wave Energy Converter in Regular Waves

2012 ◽  
Author(s):  
J. C. C. Henriques ◽  
A. F. O. Falcão ◽  
R. P. F. Gomes ◽  
L. M. C. Gato
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Phase Control ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Wave Direction ◽  
Regular Waves ◽  
Energy Converter ◽  
Chamber Volume ◽  
The Time Domain

The present paper concerns an OWC spar-buoy, possibly the simplest concept for a floating oscillating-water-column (OWC) wave energy converter. It is an axisymmetric device (and so insensitive to wave direction) consisting basically of a (relatively long) submerged vertical tail tube open at both ends, fixed to a floater that moves essentially in heave. The length of the tube determines the resonance frequency of the inner water column. The oscillating motion of the internal free surface relative to the buoy, produced by the incident waves, makes the air flow through a turbine that drives an electrical generator. It is well known that the frequency response of point absorbers like the spar buoy is relatively narrow, which implies that their performance in irregular waves is relatively poor. Phase control has been proposed to improve this situation. The present paper presents a theoretical investigation of phase control by latching of an OWC spar-buoy in which the compressibility of air in the chamber plays an important role (the latching is performed by fast closing and opening an air valve in series with the turbine). In particular such compressibility may remove the constraint of latching threshold having to coincide with an instant of zero relative velocity between the two bodies (in the case under consideration, between the floater and the OWC). The modelling is performed in the time domain for a given device geometry, and includes the numerical optimization of the air turbine rotational speed, chamber volume and latching parameters. Results are obtained for regular waves.

Comparison of Mooring Loads in Survivability Mode on the Wave Dragon Wave Energy Converter Obtained by a Numerical Model and Experimental Data

2012 ◽  
Author(s):  
Stefano Parmeggiani ◽  
Made Jaya Muliawan ◽  
Zhen Gao ◽  
Torgeir Moan ◽  
Erik Friis-Madsen
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Complex Geometry ◽  
Wave Energy Converter ◽  
Scale Model ◽  
Coupled Analysis ◽  
Small Scale ◽  
Energy Converter ◽  
Numerical Predictions ◽  
Small Scale Model

The Wave Dragon Wave Energy Converter is ready to be up-scaled to commercial size. The design and feasibility analysis of a 1.5 MW pre-commercial unit to be deployed at the DanWEC test center in Hanstholm, Denmark, is currently ongoing. With regard to the mooring system, the design has to be carried out numerically, through coupled analyses of alternative solutions. The present study deals with the preliminary hydrodynamic characterization of Wave Dragon needed in order to calibrate the numerical model to be used for the mooring design. A hydrodynamic analysis of the small scale model in the frequency domain is performed by the software HydroD, which uses WAMIT as core software. The quadratic damping term, accounting for the viscous effect, is determined through an iterative procedure aimed at matching numerical predictions on the mooring tension, derived through time domain coupled analysis, with experimental results derived from tank tests of a small scale model. Due to the complex geometry of the device, a sensitivity analysis is performed to discuss the influence of the mean position on the quality of the numerical predictions. Good correspondence is achieved between the experimental and numerical model. The numerical model is hence considered reliable for future design applications.

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