scholarly journals Hydrodynamic Efficiency of a Wave Energy Converter in Front of an Orthogonal Breakwater

2021 ◽  
Vol 9 (1) ◽  
pp. 94
Author(s):  
Dimitrios N. Konispoliatis ◽  
Spyridon A. Mavrakos
Keyword(s):  
Wave Energy ◽  
Cylindrical Wave ◽  
Wave Energy Converter ◽  
Wave Power ◽  
Linear Potential ◽  
Energy Converter ◽  
Theoretical Formulation ◽  
Hydrodynamic Efficiency ◽  
Vertical Walls ◽  
Linear Potential Theory

In the present study, the hydrodynamic efficiency of a cylindrical wave energy converter (WEC) of vertical symmetry axis and arranged in front of a reflecting orthogonal breakwater is explored. The idea is based on exploiting the anticipated amplification of the scattered and the reflected wave fields originating from the presence of the vertical walls, towards increasing the WEC’s wave power absorption due to the walls’ wave reflections. Two types of converters are examined, namely the heaving device and the oscillating water column (OWC) device, assuming linear potential theory. The associated diffraction-, motion-, and pressure-radiation problems are solved using axisymmetric eigenfunction expansions for the velocity potential around the WECs by properly accounting for the wave field’s modification due to the walls’ presence. To this end, a theoretical formulation dealing with the evaluation of the converter’s performance is presented accounting for the coupling between the WEC and the reflecting vertical walls. The results depict that the amount of the harvested wave power by the WEC in front of an orthogonal wall is amplified compared to the absorbed wave power by the same WEC in the open sea.

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.

On the Numerical Modelling of the Non Linear Behaviour of a Wave Energy Converter

2009 ◽  
Author(s):  
Aure´lien Babarit ◽  
Hakim Mouslim ◽  
Alain Cle´ment ◽  
Pauline Laporte-Weywada
Keyword(s):  
Wave Energy ◽  
Numerical Models ◽  
Computation Time ◽  
Wave Energy Converter ◽  
Linear Potential ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Cfd Models ◽  
Linear Potential Theory ◽  
Energy Converters

Wave energy converters of the wave activated body class are designed to have large amplitudes of motion, even in moderate sea states, because their efficiency is directly related with the amplitude of their motion. Hence, classical seakeeping numerical tools based on linear potential theory, which are widely used in the design process of offshore structures, are not accurate enough in the case of wave energy conversion. So, large differences between numerical predictions and wave tank experiments are often observed. On the other hand, the use of CFD models theoretically able to provide more accurate results is still difficult for wave energy applications, mainly because this requires a huge computation time. Moreover, it is well known that viscous solver have difficulties in propagatating gravity waves accurately. In this paper, we assess the potential of two advanced hydro-dynamic numerical models in the numerical modelling of wave energy converters. These numerical models are expected to provide more accurate results than classical linear theory based numerical models and faster results than CFD models. Particularly, these tools are expected to be able to deal efficiently with large motions of wave energy converters. In the first one, the hydrostatic forces and the Froude-Krylov forces are computed on the exact wetted surface of the wave energy converter, whereas radiation and diffraction forces are computed using the standard linear potential theory. Using this model, it is shown that we were able to predict the parametric roll phenomenon in the case of the SEAREV wave energy converter. In the second one, a Navier Stokes solver, based on RANS equations, is used. Comparisons are made with experiments and it is showed that this tool is able to model quite accurately viscous effects such as slamming. However, computation time is found to be long with this last tool.

Improvement of Performance of Wave Power Conversion Due to the Projecting Walls for Oscillating Water Column Type Wave Energy Converter

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hikaru Omori ◽  
Hiroyuki Osawa ◽  
Hisaaki Maeda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Prediction Method ◽  
Past Research ◽  
Wave Energy Converter ◽  
Air Pressure ◽  
Wave Power ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Energy Converter

This paper describes a method to improve the performance of primary conversion of wave power takeoff. The wave energy converter (WEC) used here was of oscillating water column (OWC) type. This method for improvement has been already proposed in past research and its usefulness has been confirmed. It involves projecting walls (PWs) being attached to the front of the inlet–outlet of the OWC. The prediction method of hydrodynamic behaviors for the OWC type WEC with PWs installed is explained in this paper. The boundary element method with the Green's function is applied, and influence of air pressure and free surface within every air-chamber was directly taken into consideration in the prediction method based on linear potential theory. Validity of the prediction method was proved by comparing the results with the results of model experiments. Series calculations are performed with the prediction method. Behaviors of air pressure, water elevation, and the efficiency of primary conversion of wave power were investigated. From the calculations, length of the PWs was shown to affect the efficiency of primary conversion. It was possible to equip the PWs so as to enable improvements in oblique waves to beam sea conditions as well as in the head sea conditions. This paper examined not only the PWs but also the application and effects of the end walls (EWs) with the slit. The EWs were very useful to improve the efficiency.

Numerical simulation of a submerged cylindrical wave energy converter

2014 ◽  
Vol 64 ◽  
pp. 132-143 ◽  
Author(s):  
M. Anbarsooz ◽  
M. Passandideh-Fard ◽  
M. Moghiman
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Cylindrical Wave ◽  
Wave Energy Converter ◽  
Energy Converter

scholarly journals Numerical simulation of a wave energy converter using linear generator

2013 ◽  
Vol 35 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Dang The Ba
Keyword(s):  
Numerical Simulation ◽  
Wave Energy ◽  
Energy Demand ◽  
Wave Energy Converter ◽  
Linear Potential ◽  
Energy Converter ◽  
Wave Condition ◽  
Mechanics Model ◽  
South Central ◽  
Offshore Wave

This paper presents results of numerical simulation for a wave energy converter using linear permanent magnet generator. The use of linear permanent generator has advantages of simple structure, minimizing mechanical loose... On the base of mechanics model, a system of equations describing the operation of the device under linear potential wave was obtained. The magnetic field in generator was calculated by Flex-PDE software. The system of movement equations was numerically solved with Matlab.Various calculations were performed with different parameters of wave conditions and device's structures to determine the device’s configuration for a 300 W output power for the offshore wave condition in South-Central offshore of Vietnam. The results also show potential of developing the wave energy conversion to meet the energy demand in some coastal and island regions of Vietnam.

scholarly journals Hydrodynamic Performance of a Hybrid System Combining a Fixed Breakwater and a Wave Energy Converter: An Experimental Study

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5740
Author(s):  
Wei Peng ◽  
Yingnan Zhang ◽  
Xueer Yang ◽  
Jisheng Zhang ◽  
Rui He ◽  
...  
Keyword(s):  
Experimental Study ◽  
Hybrid System ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Wave Power ◽  
Energy Converter ◽  
Power Extraction ◽  
Wave Induced

In this paper, a hybrid system integrating a fixed breakwater and an oscillating buoy type wave energy converter (WEC) is introduced. The energy converter is designed to extract the wave power by making use of the wave-induced heave motions of the three floating pontoons in front of the fixed breakwater. A preliminary experimental study is carried out to discuss the hydrodynamic performance of the hybrid system under the action of regular waves. A scale model was built in the laboratory at Hohai University, and the dissipative force from racks and gearboxes and the Ampere force from dynamos were employed as the power take-off (PTO) damping source. During the experiments, variations in numbers of key parameters, including the wave elevation, free response or damped motion of the floating pontoons, and the voltage output of the dynamos were simultaneously measured. Results indicate that the wave overtopping and breaking occurring on the upper surfaces of floating pontoons have a significant influence on the hydrodynamic performance of the system. For moderate and longer waves, the developed system proves to be effective in attenuating the incident energy, with less than 30% of the energy reflected back to the paddle. More importantly, the hydrodynamic efficiency of energy conversion for the present device can achieve approximately 19.6% at the lowest wave steepness in the model tests, implying that although the WEC model harnesses more energy in more energetic seas, the device may be more efficient for wave power extraction in a less energetic sea-state.

The influence of oblique waves on the hydrodynamic efficiency of an onshore OWC wave energy converter

2021 ◽  
Author(s):  
Ayrton Alfonso Medina Rodríguez ◽  
Rodolfo Silva Casarín ◽  
Jesús María Blanco Ilzarbe
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Oblique Waves ◽  
Hydrodynamic Efficiency

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.

Sign in / Sign up

Export Citation Format

Share Document