scholarly journals A Study of the Hydrodynamic Performance of a Pitch-type Wave Energy Converter–Rotor

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 842 ◽  
Author(s):  
Sunny Kumar Poguluri ◽  
Il-Hyoung Cho ◽  
Yoon Hyeok Bae
Keyword(s):  
Wave Energy ◽  
Energy Method ◽  
Potential Flow ◽  
Equation Of Motion ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Linear Potential ◽  
Viscous Damping ◽  
Energy Converter ◽  
Free Decay

The effect of hydrodynamic performance of the wave energy converter (WEC)–rotor based on linear potential flow theory due to nonlinear viscous damping was investigated. Free decay tests were conducted using computational fluid dynamics (CFD) to obtain the viscous damping moment. The commonly used procedure for obtaining the damping moment is based on peak amplitudes which normally require a long time history records. Such long free decay records may not be possible in nodding WEC rotor due high damping. The energy method proposed by Bass and Haddara requires only the short and full range of the recorded data. This method provides sufficiently good results when the bodies have high damping. The method equates the rate of change of the total energy of a body undergoing free rolling/pitching to the rate of energy dissipated by the damping. The present study adopts a similar methodology for estimating the linear and linear plus quadratic damping. To incorporate the nonlinear viscous damping moment in the linear equation of motion, an equivalent linearization concept is used without neglecting the nonlinear damping effects. The hydrodynamic coefficients obtained from the linear potential flow theory, nonlinear viscous damping moment from the energy method and estimated PTO damping are used to solve the equation of motion of the WEC rotor. The estimated pitch free decay data shows good agreement with the simulated CFD results when compared to the linear viscous damping moment and better agreement is obtained with linear plus quadratic viscous damping moment. The regular and irregular wave analyses show that a considerable effect on the hydrodynamic performance of the WEC rotor is observed when the linear and linear plus quadratic viscous damping are included.

scholarly journals Effect of Dissipation on the Moonpool-Javelin Wave Energy Converter

2021 ◽  
Vol 9 (12) ◽  
pp. 1444
Author(s):  
Dan Yu ◽  
Keyi Wang ◽  
Yeqing Jin ◽  
Fankai Kong ◽  
Hailong Chen ◽  
...  
Keyword(s):  
Wave Energy ◽  
Potential Flow ◽  
Wave Force ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Energy Converter ◽  
Viscous Term ◽  
Cfd Method ◽  
The Time Domain

In this work, the hydrodynamic performance of a novel wave energy converter (WEC) configuration which combines a moonpool platform and a javelin floating buoy, called the moonpool–javelin wave energy converter (MJWEC), was studied by semianalytical, computational fluid dynamics (CFD), and experimental methods. The viscous term is added to the potential flow solver to obtain the hydrodynamic coefficients. The wave force, the added mass, the radiation damping, the wave capture, and the energy efficiency of the configuration were assessed, in the frequency and time domains, by a semianalytical method. The CFD method results and the semianalytical results were compared for the time domain by introducing nonlinear power take-off (PTO) damping; additionally, the viscous dissipation coefficients under potential flow could be confirmed. Finally, a 1:10 scale model was physically tested to validate the numerical model and further prove the feasibility of the proposed 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 Experimental investigation on the hydrodynamic performance of a wave energy converter

2017 ◽  
Vol 31 (3) ◽  
pp. 370-377 ◽  
Author(s):  
Xiong-bo Zheng ◽  
Yong Ma ◽  
Liang Zhang ◽  
Jin Jiang ◽  
Heng-xu Liu
Keyword(s):  
Experimental Investigation ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Energy Converter

scholarly journals Establishment of Motion Model for Wave Capture Buoy and Research on Hydrodynamic Performance of Floating-Type Wave Energy Converter

2015 ◽  
Vol 22 (s1) ◽  
pp. 106-111 ◽  
Author(s):  
Hongtao Gao ◽  
Biao Li
Keyword(s):  
Wave Energy ◽  
Structural Parameters ◽  
Absorption Efficiency ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Motion Model ◽  
Energy Converter ◽  
Type Wave ◽  
Energy Absorption Efficiency ◽  
Floating Type

Abstract Floating-type wave energy converter has the advantages of high wave energy conversion efficiency, strong shock resistance ability in rough sea and stable output power. So it is regarded as a promising energy utilization facility. The research on hydrodynamic performance of wave capture buoys is the precondition and key to the wave energy device design and optimization. A simplified motion model of the buoys in the waves is established. Based on linear wave theory, the equations of motion of buoys are derived according to Newton’s second law. The factors of wave and buoys structural parameters on wave energy absorption efficiency are discussed in the China’s Bohai Sea with short wave period and small wave height. The results show that the main factor which affects the dynamic responses of wave capture buoys is the proximity of the natural frequency of buoys to the wave period. And the incoming wave power takes a backseat role to it at constant wave height. The buoys structural parameters such as length, radius and immersed depth, influence the wave energy absorption efficiency, which play significant factors in device design. The effectiveness of this model is validated by the sea tests with small-sized wave energy devices. The establishment methods of motion model and analysis results are expected to be helpful for designing and manufacturing of floating-type wave energy converter.

Nonlinear Time-Domain Simulation of the Heaving-Buoy Type Wave Energy Converter by Using Three-Dimensional Potential Numerical Wave Tank Under Irregular Wave Conditions

2020 ◽  
Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo ◽  
Moo-Hyun Kim
Keyword(s):  
Wave Energy ◽  
Time Domain ◽  
Three Dimensional ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Numerical Wave Tank ◽  
Energy Converter ◽  
Wave Tank ◽  
Type Wave ◽  
Numerical Wave

Abstract The aim of this paper is to evaluate the hydrodynamic performance of a heaving buoy type wave energy converter (WEC) and power take-off (PTO) system. To simulate the nonlinear behavior of the WEC with PTO system, a three-dimensional potential numerical wave tank (PNWT) was developed. The PNWT is a numerical analysis tool that can accurately reproduce experiments in physical wave tanks. The developed time-domain PNWT utilized the previously developed NWT technique and newly adopted the side wall damping area. The PNWT is based on boundary element method with constant panels. The mixed Eulerian-Lagrangian method (MEL) and acceleration potential approach were adopted to simulate the nonlinear behaviors of free-surface nodes associated with body motions. The PM spectrum as an irregular incident wave condition was applied to the input boundary. A floating or fixed type WEC structure was placed in the center of the computational domain. A hydraulic PTO system composed of a hydraulic cylinder, hydraulic motor and generator was modeled with approximate Coulomb damping force and applied to the WEC system. Using the integrated numerical model of the WEC with PTO system, nonlinear interaction of irregular waves, the WEC structure, and the PTO system were simulated in the time domain. The optimal hydraulic pressure of the PTO condition was predicted. The hydrodynamic performance of the WEC was evaluated by comparing the linear and nonlinear analytical results and highlighted the importance accounting for nonlinear free surfaces.

Analysis of the Hydrodynamic Performance of an Oyster Wave Energy Converter Using Star-CCM+

2019 ◽  
Vol 18 (2) ◽  
pp. 153-159
Author(s):  
Zheng Yuan ◽  
Liang Zhang ◽  
Binzhen Zhou ◽  
Peng Jin ◽  
Xiongbo Zheng
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Energy Converter

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.

scholarly journals Nonlinear and viscous effects on the hydrodynamic performance of a fixed OWC wave energy converter

2018 ◽  
Vol 131 ◽  
pp. 42-50 ◽  
Author(s):  
Rong-quan Wang ◽  
De-zhi Ning ◽  
Chong-wei Zhang ◽  
Qing-ping Zou ◽  
Zhen Liu
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Viscous Effects ◽  
Energy Converter
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