scholarly journals Hydrodynamic Analysis of a Multibody Wave Energy Converter in Regular Waves

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1233
Author(s):  
Sunny Kumar Poguluri ◽  
Dongeun Kim ◽  
Yoon Hyeok Bae
Keyword(s):  
Wave Energy ◽  
Numerical Models ◽  
Wave Energy Converter ◽  
Optimal Time ◽  
Q Factor ◽  
Energy Converter ◽  
Multiple Wave ◽  
Hydrodynamic Analysis ◽  
Heading Angle ◽  
Extracted Power

A performance assessment of wave power absorption characteristics of isolated and multiple wave energy converter (WEC) rotors was presented in this study for various wave-heading angles and wave frequencies. Numerical hydrodynamic analysis of the WEC was carried out using the three-dimensional linear boundary element method (BEM) and nonlinear computational fluid dynamics (CFD). Experimental results were used to validate the adopted numerical models. Influence with and without power take-off (PTO) was estimated on both isolated and multiple WEC rotors. Furthermore, to investigate the interaction effect among WECs, a q-factor was used. Incorporation of viscous and PTO damping into the linear BEM solution shows the maximum reduction focused around peak frequency but demonstrated an insignificant effect elsewhere. The q-factor showed both constructive and destructive interactions with the increase of the wave-heading angle and wave frequencies. Further investigation based on the prototype WEC rotor was carried, and calculated results of the linear BEM and the nonlinear CFD were compared. The pitch response and q-factor of the chosen wave frequencies demonstrated satisfactory consistency between the linear BEM and nonlinear CFD results, except for some wave frequencies. Estimated optimal time-averaged power using linear BEM show that the maximum extracted power close to the zero wave-heading angle around the resonance frequency decreases as the wave-heading angle increases. Overall, the linear BEM on the extracted power is overestimated compared with the nonlinear CFD results.

Hydrodynamic analysis of a novel wave energy converter: Hull Reservoir Wave Energy Converter (HRWEC)

2021 ◽  
Vol 170 ◽  
pp. 1020-1039
Author(s):  
S.D.G.S.P. Gunawardane ◽  
G.A.C.T. Bandara ◽  
Young-Ho Lee
Keyword(s):  
Wave Energy ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Hydrodynamic Analysis

scholarly journals KNSwing—On the Mooring Loads of a Ship-Like Wave Energy Converter

2019 ◽  
Vol 7 (2) ◽  
pp. 29
Author(s):  
Kim Nielsen ◽  
Jonas Thomsen
Keyword(s):  
Numerical Model ◽  
Wave Energy ◽  
Numerical Models ◽  
Breaking Waves ◽  
Wave Energy Converter ◽  
Experimental Results ◽  
Irregular Waves ◽  
Mooring System ◽  
Energy Converter ◽  
The Waves

The critical function of keeping a floating Wave Energy Converter in position is done by a mooring system. Several WECs have been lost due to failed moorings, indicating that extreme loads, reliability and durability are very important aspects. An understanding of the interaction between the WEC’s motion in large waves and the maximum mooring loads can be gained by investigating the system at model scale supported by numerical models. This paper describes the testing of a novel attenuator WEC design called KNSwing. It is shaped like a ship facing the waves with its bow, which results in low mooring loads and small motions in most wave conditions when the structure is longer than the waves. The concept is tested using an experimental model at scale 1:80 in regular and irregular waves, moored using rubber bands to simulate synthetic moorings. The experimental results are compared to numerical simulations done using the OrcaFlex software. The experimental results show that the WEC and the mooring system survives well, even under extreme and breaking waves. The numerical model coefficient concerning the nonlinear drag term for the surge motion is validated using decay tests. The numerical results compare well to the experiments and, thereby, the numerical model can be further used to optimize the mooring system.

A New Class of Wave Energy Converter: The Floating Pendulum Dynamic Vibration Absorber

2017 ◽  
Author(s):  
Hayden Marcollo ◽  
Jonathan Gumley ◽  
Paul Sincock ◽  
Nicholas Boustead ◽  
Adrian Eassom ◽  
...  
Keyword(s):  
Wave Energy ◽  
Numerical Models ◽  
Low Cost ◽  
Wave Energy Converter ◽  
Floating Body ◽  
Vibration Absorber ◽  
Energy Converter ◽  
Dynamic Vibration Absorber ◽  
New Class ◽  
Dynamic Vibration

A new class of Wave Energy Converter (WEC) is presented — the Floating Pendulum Dynamic Vibration Absorber (FPDVA). This concept offers significant design benefits to other WEC technology in the form of low cost installation and mechanical moving components located above the waterline only. The key elements of the FPDVA concept are highlighted. The performance of the concept is demonstrated through numerical modeling with calibration of the numerical models via physical tank testing. The Power Take Off (PTO) system is described, and the bench tests are presented. A discussion about the control systems required to operate the FPDVA system and the likely floating body mooring configurations are also presented. The technology has patent pending status. Future phased development of the technology is planned to progress its Technology Readiness Level (TRL) status from TRL 4 to TRL 9.

scholarly journals The performance of the Mocean M100 wave energy converter described through numerical and physical modelling

2020 ◽  
Vol 3 (1) ◽  
pp. 11-19
Author(s):  
J. Cameron McNatt ◽  
Christopher H. Retzler
Keyword(s):  
Frequency Domain ◽  
Wave Energy ◽  
Time Domain ◽  
Numerical Models ◽  
Average Power ◽  
Physical Modelling ◽  
Wave Energy Converter ◽  
Domain Model ◽  
Energy Converter ◽  
Cost Of Energy

Mocean Energy has designed a 100-kW hinged-raft wave energy converter (WEC), the M100, which has a novel geometry that reduces the cost of energy by improving the ratios of power per size and power per torque. The performance of the M100 is shown through the outputs of frequency-domain and time-domain numerical models, which are compared with those from 1/20th scale wave-tank testing. Results show that for the undamped, frequency-domain model, there are resonant peaks in the response at 6.6 and 9.6 s, corresponding to wavelengths that are 1.9 and 3.7 times longer than the machine. With the inclusion of power-take-off and viscous damping, the power response as a function of frequency shows a broad bandwidth and a hinge flex amplitude of 12-20 degrees per meter of wave amplitude. Comparison between the time-domain model and physical data in a variety of sea states, up to a significant wave height of 4.5 m, show agreements within 10% for average power absorption, which is notable because only simple, nonlinear, numerical models were used. The M100 geometry results in a broad-banded, large amplitude response due to its asymmetric shape, which induces coupling between modes of motion.

Dynamic Response of a Wave Energy Converter With Resonant U-Tank

2020 ◽  
Author(s):  
Adetoso Justus Afonja ◽  
Stefano Brizzolara
Keyword(s):  
Dynamic Model ◽  
Wave Energy ◽  
Time Domain ◽  
Integrated System ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Wave Condition ◽  
Head Waves ◽  
Tank System ◽  
Extracted Power

Abstract This paper describes the concept design and preliminary dynamic analysis of a pitching wave energy converter (WEC) device, based on a pitching resonant floater, a pitch resonance tuning tank system and Wells turbines in regular head waves. The device has a bow/stern symmetry, which gives an advantage of the U-tank been strongly coupled with the floater in the pitch degree of freedom and both chambers will have their separate pneumatic turbines. The integrated dynamic model coupling the U-tank system as given with the motion of the floating body in regular waves and the power take off (PTO) device is physically and mathematically defined. This coupling effectively creates a multi-body dynamic system and thus alters the motion response amplitude operator of the device in waves creating multiple resonance peaks. The integrated dynamic model is solved in time domain to account for non-linearities. Excitation, radiation and diffraction forces are calculated in frequency domain from a 3D boundary element method (BEM) and corrected by Cummins equation (convolution integral) for memory effects to be used in the time domain solution. The time dependent motion of the free surface creates a pressure difference inside the chamber with respect to the atmosphere which is used by the PTO turbine. The dynamic model of the integrated system is used to predict the maximum extracted power for a given incident wave power. A systematic study, considering a change in PTO damping is performed to search for the maximum extracted power in any given regular wave condition.

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