scholarly journals Three-dimensional effects on the performance of multi-level overtopping wave energy converter

2021 ◽  
Vol 1137 (1) ◽  
pp. 012016
Author(s):  
S. Jungrungruengtaworn ◽  
N. Thaweewat ◽  
B.S. Hyun
Author(s):  
Ryan G. Coe ◽  
Diana L. Bull

A three dimensional time-domain model, based on Cummins equation, has been developed for an axisymmetric point absorbing wave energy converter (WEC) with an irregular cross section. This model incorporates a number of nonlinearities to accurately account for the dynamics of the device: hydrostatic restoring, motion constraints, saturation of the power-take-off force, and kinematic nonlinearities. Here, an interpolation model of the hydrostatic restoring reaction is developed and compared with a surface integral based method. The effects of these nonlinear hydrostatic models on device dynamics are explored by comparing predictions against those of a linear model. For the studied WEC, the interpolation model offers a large improvement over a linear model and is roughly two orders-of-magnitude less computationally expensive than the surface integral based method.


2016 ◽  
Vol 693 ◽  
pp. 484-490
Author(s):  
Ying Xue Yao ◽  
Hai Long Li ◽  
Jin Ming Wu ◽  
Liang Zhou

Duck wave energy converter has the advantages of high conversion efficiency, simple construction, low cost relative to other wave power device. In the paper, the numerical simulation of the response of the converter was calculated by the AQWA software which based on the three dimensional potential flow theories. The results show that the pitch angle appear the peak when the incident wave frequency is 1rad/s and the maximum of the pitch angle come out as the linear wave normally incident the duck body, which means duck wave energy converter can absorb more wave energy in this angular frequency. The above research can provide reference for the design of the duck wave energy converter.


Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo ◽  
Moo-Hyun Kim

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.


2013 ◽  
Vol 716 ◽  
pp. 566-596 ◽  
Author(s):  
S. Crowley ◽  
R. Porter ◽  
D. V. Evans

AbstractA novel design concept for a wave energy converter (WEC) is presented and analysed. Its purpose is to balance the theoretical capacity for power absorption against engineering design issues which plague many existing WEC concepts. The WEC comprises a fully submerged buoyant circular cylinder tethered to the sea bed by a simple mooring system which permits coupled surge and roll motions of the cylinder. Inside the cylinder a mechanical system of pendulums rotate with power generated by the relative rotation rates of the pendulums and the cylinder. The attractive features of this design include: making use of the mooring system as a passive component of the power take off (PTO); using a submerged device to protect it from excessive forces associated with extreme wave conditions; locating the PTO within the device and using a PTO mechanism which does not need to be constrained; exploiting multiple resonances of the system to provide a broad-banded response. A mathematical model is developed which couples the hydrodynamic waves forces on the device with the internal pendulums under a linearized framework. For a cylinder spanning a wave tank (equivalent to a two-dimensional assumption) maximum theoretical power for this WEC device is limited to 50 % maximum efficiency. However, numerical results show that a systematically optimized system can generate theoretical efficiencies of more than 45 % over a 6 s range of wave period containing most of the energy in a typical energy spectrum. Furthermore, three-dimensional results for a cylinder of finite length provide evidence that a cylinder device twice the length of its diameter can produce more than its own length in the power of an equivalent incident wave crest.


2021 ◽  
Vol 247 ◽  
pp. 114717
Author(s):  
Hengming Zhang ◽  
Binzhen Zhou ◽  
Jun Zang ◽  
Christopher Vogel ◽  
Peng Jin ◽  
...  

2014 ◽  
Vol 518 ◽  
pp. 209-214 ◽  
Author(s):  
Dong Jiao Wang ◽  
Shou Qiang Qiu ◽  
Jia Wei Ye

Based on the three dimensional potential theory, numerical studies were carried out to investigate the hydrodynamics of a single-acting trapezoidal pendulum wave energy converter in regular waves by using time domain analysis. The nonlinear viscous damping was also taken into account, and the influence of power take-off damping on the motion responses and output performances were analyzed. Comparisons of experimental and numerical results were performed as part of the validation process.


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