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 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 Influence of Central Platform on Hydrodynamic Performance of Semi-Submerged Multi-Buoy Wave Energy Converter

2019 ◽  
Vol 8 (1) ◽  
pp. 12
Author(s):  
Yuan Hu ◽  
Shaohui Yang ◽  
Hongzhou He ◽  
Hu Chen
Keyword(s):  
Numerical Analysis ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Theoretical Research ◽  
Width Ratio ◽  
Energy Converter ◽  
Wave Condition ◽  
Energy Capture ◽  
Central Platform

The influence of the central platform on hydrodynamic performance of a wave energy converter (WEC) has remained elusive. To approach this dearth of relevant theoretical research, this paper presents a semi-submerged multi-buoy WEC and the results of the numerical analysis at different dimension parameters of the central platform of the WEC. The WEC consists of three oscillating buoys hinged with a central platform through multiple actuating arms. Numerical analysis revealed that there exists a relationship between the hydrodynamic performance of device and the geometry of the central platform. At the given wave condition, different central platform size would obviously affect the hydrodynamic performance and wave energy capture width ratio of the semi-submerged multi-buoy WEC. Additionally, appropriately increasing central platform draft would help to improve the wave energy capture capability of the oscillating buoys.

Experimental investigation on hydrodynamic performance of a dual pontoon–power take-off type wave energy converter integrated with floating breakwaters

2018 ◽  
Vol 233 (4) ◽  
pp. 991-999 ◽  
Author(s):  
Dezhi Ning ◽  
Xuanlie Zhao ◽  
Ming Zhao ◽  
Haigui Kang
Keyword(s):  
Transmission Coefficient ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Width Ratio ◽  
Frequency Range ◽  
Effective Frequency ◽  
Energy Converter ◽  
Damping Force ◽  
Capture Width Ratio

As an extension of the single pontoon wave energy converter–type breakwater, a wave energy converter–type breakwater equipped with dual pontoon–power take-off system is proposed to broaden the effective frequency range (for transmission coefficient KT < 0.5 and capture width ratio η > 20%). The wave energy converter–type breakwater with dual pontoon–power take-off system consists of a pair of heave-type pontoons and power take-off systems for which the power take-off system is installed to harvest the kinetic energy of heave motion of the pontoon. In this paper, we experimentally confirm the advantage of the wave energy converter–type breakwater with dual pontoon–power take-off system over the one with a single pontoon–power take-off system. Both wave energy converter–type breakwater with dual pontoon–power take-off system and that with single pontoon–power take-off system are tested in regular waves. A (electronic) current controller–magnetic powder brake system is used to simulate the power take-off system. The characteristics of power take-off system are investigated and results showed that the power take-off system can simulate the (approximate) Coulomb damping force well. Experimental results reveal that the wave energy converter–type breakwater with dual pontoon–power take-off system broadens the effective frequency range compared with the single pontoon–power take-off system with the same pontoon volume (i.e. the displacement of the pontoon). Specifically, the transmission coefficient of the system is smaller while the system in relative longer waves. Furthermore, the capture width ratio of system can be improved.

scholarly journals Hydrodynamic Investigation of a Dual-Cylindrical OWC Wave Energy Converter Integrated into a Fixed Caisson Breakwater

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 896 ◽  
Author(s):  
Chang Wan ◽  
Can Yang ◽  
Qinghe Fang ◽  
Zaijin You ◽  
Jing Geng ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Analytical Model ◽  
Wave Energy ◽  
Velocity Potential ◽  
Wave Energy Converter ◽  
Published Data ◽  
Geometrical Parameters ◽  
Linear Potential ◽  
Energy Converter ◽  
Cylindrical Column

A fixed dual cylindrical oscillating water column (OWC) acting as a breakwater-type wave energy converter (WEC) is proposed to harvest the wave energy effectively for shallow offshore sites. An analytical model is developed to investigate the hydrodynamic characteristics and the energy capture capacity of the cylindrical OWC device in severe waves. Based on the linear potential flow theory, the analytical solutions of the velocity potential in diffraction mode are solved by matching the Eigen-function expansion technique, and the continuous conditions of the velocity potential and fluid velocity between the computational sub-domains are involved in solving the problem for determining a solution. The proposed model is verified against the published data. The effects of the wave height, the angle of chamber clapboard and the radius of the inner and outer cylindrical column on the energy conversion efficiency are investigated in this paper. To improve the energy conversion performance and obtain a faster prediction for structural optimization of the cylindrical OWC, the geometrical parameters are further discussed in the analytical model. The results indicate that the geometrical parameters of the chamber have significant effects on the wave energy absorption efficiency. It is found that the effective frequency bandwidth of the dual cylindrical column can be broadened by improving the angle of the chamber clapboard and the inner–outer cylinder diameter ratio.

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 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

Uncertainty in Wave Basin Testing of a Fixed Oscillating Water Column Wave Energy Converter

2021 ◽  
Author(s):  
Frances M. Judge ◽  
Eoin Lyden ◽  
Michael O'Shea ◽  
Brian Flannery ◽  
Jimmy Murphy
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Width Ratio ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
The Monte Carlo Method ◽  
Wave Basin ◽  
Measurement Location ◽  
The Impact

Abstract This research presents a methodology for carrying out uncertainty analysis on measurements made during wave basin testing of an oscillating water column wave energy converter. Values are determined for Type A and Type B uncertainty for each parameter of interest, and uncertainty is propagated using the Monte Carlo method to obtain an overall Expanded Uncertainty with a 95% confidence level associated with the Capture Width Ratio of the device. An analysis into the impact of reflections on the experimental results reveals the importance of identifying the incident and combined wave field at each measurement location used to determine device performance, in order to avoid misleading results.

scholarly journals An efficient multi-factor geometry optimization based on motion analysis and resonance response for hinged double-body floating wave energy converter

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042095015
Author(s):  
Biao Li ◽  
Fangfang Sui ◽  
Bingsong Yang
Keyword(s):  
Motion Analysis ◽  
Wave Energy ◽  
Geometry Optimization ◽  
Geometric Optimization ◽  
Wave Energy Converter ◽  
Geometrical Parameters ◽  
Optimization Strategy ◽  
Energy Converter ◽  
Pitching Motion ◽  
Resonance Response

In the practical engineering applications of multi-body floating wave energy converter (WEC), the traditional geometric optimization is always expensive and time-consuming. This study aim to propose a more efficient geometry optimization strategy with a hinged double-body floating WEC as the study object. The influences of geometric parameters of the buoys on the pitching motion and energy conversion ability are analyzed by numerical simulation. Simulation results show that the resonance state of the pitching motion of the buoys mainly depends on their radius and draft rather than the length; But the length of the buoys, rather than the radius and draft, always has a significant effect on the pitching phase difference of the adjacent buoys. Based on the motion analysis and resonance response, an efficient multi-factor geometry optimization strategy is put forwarded. By the strategy, the sub-optimal and optimal geometrical parameters are solved out quickly at several typical wave conditions of China Seas. The results indicate that the optimal total length of WEC is approximately equal to the wave length. The optimal diameter of buoys is about 25% of the length of buoys. And the optimal draft should attain about 61% of the diameter.

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.

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