scholarly journals Performance of an Array of Oblate Spheroidal Heaving Wave Energy Converters in Front of a Wall

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 188 ◽  
Author(s):  
Eva Loukogeorgaki ◽  
Ifigeneia Boufidi ◽  
Ioannis K. Chatjigeorgiou
Keyword(s):  
Wave Energy ◽  
Vertical Wall ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Power Absorption ◽  
Enhanced Absorption ◽  
Wave Energy Converters ◽  
Oblate Spheroidal ◽  
Specific Frequency ◽  
Energy Converters

In this paper, we investigate the performance of a linear array of five semi-immersed, oblate spheroidal heaving Wave Energy Converters (WECs) in front of a bottom-mounted, finite-length, vertical wall under perpendicular to the wall regular waves. The diffraction and radiation problems are solved in the frequency domain by utilizing the conventional boundary integral equation method. Initially, to demonstrate the enhanced absorption ability of this array, we compare results with the ones corresponding to arrays of cylindrical and hemisphere-shaped WECs. Next, we investigate the effect of the array’s distance from the wall and of the length of the wall on the physical quantities describing the array’s performance. The results illustrate that the array’s placement at successively larger distances from the wall, up to three times the WECs’ radius, induces hydrodynamic interactions that improve the array’s hydrodynamic behavior, and thus its power absorption ability. An increase in the length of the wall does not lead to any significant power absorption improvement. Compared to the isolated array, the presence of the wall affects positively the array’s power absorption ability at specific frequency ranges, depending mainly on the array’s distance from the wall. Finally, characteristic diffracted wave field patterns are presented to interpret physically the occurrence of the local minima of the heave exciting forces.

scholarly journals Frequency-Based Performance Analysis of an Array of Wave Energy Converters around a Hybrid Wind–Wave Monopile Support Structure

2020 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Sofia Gkaraklova ◽  
Pavlos Chotzoglou ◽  
Eva Loukogeorgaki
Keyword(s):  
Wave Energy ◽  
Wind Wave ◽  
Radial Distance ◽  
Boundary Integral ◽  
Irregular Waves ◽  
Diffraction Radiation ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Oblate Spheroidal ◽  
Energy Converters

In this paper, we investigate, in the frequency domain, the performance (hydrodynamic behavior and power absorption) of a circular array of four semi-immersed heaving Wave Energy Converters (WECs) around a hybrid wind–wave monopile (circular cylinder). The diffraction/radiation problem is solved by deploying the conventional boundary integral equation method. Oblate-spheroidal and hemispherical-shaped WECs are considered. For each geometry, we assess the effect of the array’s net radial distance from the monopile and of the incident wave direction on the array’s performance under regular waves. The results illustrate that by placing the oblate spheroidal WECs close to the monopile, the array’s power absorption ability is enhanced in the low frequency range, while the opposite occurs for higher wave frequencies. For hemispherical-shaped WECs, the array’s power absorption ability is improved when the devices are situated close to the monopile. The action of oblique waves, with respect to the WECs’ arrangement, increases the absorbed power in the case of oblate spheroidal WECs, while these WECs show the best power absorption ability among the two examined geometries. Finally, for the most efficient array configuration, consisting of oblate spheroidal WECs situated close to the monopile, we utilize an “active” Power Take-Off (PTO) mechanism, facilitating the consideration of a variable with frequency PTO damping coefficient. By deploying this mechanism, the power absorption ability of the array is significantly enhanced under both regular and irregular waves.

scholarly journals Layout optimization of heaving Wave Energy Converters linear arrays in front of a vertical wall

2021 ◽  
Author(s):  
Eva Loukogeorgaki ◽  
Constantine Michailides ◽  
George Lavidas ◽  
Ioannis K. Chatjigeorgiou
Keyword(s):  
Wave Energy ◽  
Vertical Wall ◽  
Layout Optimization ◽  
Linear Arrays ◽  
Wave Energy Converters ◽  
Energy Converters

scholarly journals Wave Power Absorption by Arrays of Wave Energy Converters in Front of a Vertical Breakwater: A Theoretical Study

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1985 ◽  
Author(s):  
Dimitrios N. Konispoliatis ◽  
Spyridon A. Mavrakos
Keyword(s):  
Wave Energy ◽  
Cylindrical Wave ◽  
Hydrodynamic Characteristics ◽  
Linear Potential ◽  
Theoretical Evaluation ◽  
Power Absorption ◽  
Array Configuration ◽  
Wave Energy Converters ◽  
Vertical Breakwater ◽  
Energy Converters

The present paper deals with the theoretical evaluation of the efficiency of an array of cylindrical Wave Energy Converters (WECs) having a vertical symmetry axis and placed in front of a reflecting vertical breakwater. Linear potential theory is assumed, and the associated diffraction and motion radiation problems are solved in the frequency domain. Axisymmetric eigenfunction expansions of the velocity potential are introduced into properly defined ring-shaped fluid regions surrounding each body of the array. The potential solutions are matched at the boundaries of adjacent fluid regions by enforcing continuity of the hydrodynamic pressures and redial velocities. A theoretical model for the evaluation of the WECs’ performance is developed. The model properly accounts for the effect of the breakwater on each body’s hydrodynamic characteristics and the coupling between the bodies’ motions and the power take-off mechanism. Numerical results are presented and discussed in terms of the expected power absorption. The results show how the efficiency of the array is affected by (a) the distance between the devices and the wall, (b) the shape of the WEC array configuration, as well as (c) the angle of the incoming incident wave.

Numerical Modeling and Evaluation of Wave Energy Converters

2009 ◽  
Author(s):  
Heather Peng ◽  
Wei Qiu ◽  
Don Spencer
Keyword(s):  
Numerical Modeling ◽  
Frequency Domain ◽  
Wave Energy ◽  
Energy Production ◽  
Wave Power ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Numerical Studies ◽  
The Waves ◽  
Energy Converters

Wave energy converters use the motion of floating or submerged bodies to extract energy from the waves. Power absorption can be simulated using a simple linear damper with a resistance to motion which is proportional to velocity. Because of the interaction between energy production and motion, there will be an optimum rate of energy production for each wave frequency. Too much damping or too little damping can cause little energy produced. The wave absorption range also depends on the tuned frequency. In this paper, the maximum rates of energy absorption for submerged and floating wave energy converters are evaluated by employing the panel-free method for the motions of the converters in the frequency domain. A general expression for the wave power absorption is described. Numerical studies show that the optimal energy efficiencies of wave energy converters can be well predicted by employing the panel-free method for motion computations.

scholarly journals Wave energy resource variation off the west coast of Ireland and its impact on realistic wave energy converters’ power absorption

2018 ◽  
Vol 224 ◽  
pp. 205-219 ◽  
Author(s):  
Markel Penalba ◽  
Alain Ulazia ◽  
Gabriel Ibarra-Berastegui ◽  
John Ringwood ◽  
Jon Sáenz
Keyword(s):  
Wave Energy ◽  
West Coast ◽  
Energy Resource ◽  
The West ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Energy Converters ◽  
Resource Variation
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