A Novel Geno-Fuzzy Based Model for Hydrodynamic Efficiency Prediction of an Oscillating Water Column for Various Front Wall Openings Power Take-Off Dampings and Incident Wave Steepnesses

2021 ◽  
Author(s):  
Abdüsselam Altunkaynak ◽  
Anil Çelik
Keyword(s):  
Water Column ◽  
Incident Wave ◽  
Front Wall ◽  
Oscillating Water Column ◽  
Hydrodynamic Efficiency ◽  
Wall Openings

Numerical and Geometrical Analysis of the Onshore Oscillating Water Column Wave Energy with a Ramp

2021 ◽  
Vol 412 ◽  
pp. 11-26
Author(s):  
Marla Rodrigues Oliveira ◽  
Elizaldo Domingues Santos ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha ◽  
Mateus das Neves Gomes
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Degrees Of Freedom ◽  
Design Method ◽  
Geometric Analysis ◽  
Relative Difference ◽  
Front Wall ◽  
Multiphase Model ◽  
Oscillating Water Column ◽  
Worst Case

This study is about a two-dimensional numerical analysis of the influence of a ramp in front on an oscillating water column wave energy converter (OWC-WEC). The main purpose was to evaluate, numerically and geometrically, the effect of using a ramp variation in relation to the frontal wall on the hydropneumatic power of the OWC-WEC. The constructal design method was applied for geometric analysis. The problem had a geometric constraint: the area of the ramp (A2) and two degrees of freedom: H2 / L2 (ratio of the height and length of the ramp) and L4 (the distance of the ramp concerning the OWC-WEC front wall). In numerical simulations, the equations of conservation of mass, momentum, and an equation for the transport of volumetric fraction were solved using the finite volume method (FVM). The multiphase model volume of fluid (VOF) was applied for the air-water interaction. Thus, the increase in the H2/L2 ratio resulted in a decrease of the root mean square (RMS) of the available hydropneumatic power (Phyd). By varying the distance L4, the better case was = 6 m and / = 0.025 and the worst case was = 1 m and / = 0.2. The relative difference between the better RMS Phyd = 150.7957 W and the worst Phyd = 73.1164 W reached up to a hundred and six percent.

Wave energy extraction by an oscillating water column with a gap on the fully submerged front wall

2012 ◽  
Vol 37 ◽  
pp. 174-182 ◽  
Author(s):  
Utku Şentürk ◽  
Aydoğan Özdamar
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Front Wall ◽  
Energy Extraction ◽  
Oscillating Water Column

Performance of a Shore Fixed Oscillating Water Column Device for Different Bottom Slopes and Front Wall Drafts: A Study Based on Computational Fluid Dynamics and BIEM

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Piyush Mohapatra ◽  
K. G. Vijay ◽  
Anirban Bhattacharyya ◽  
Trilochan Sahoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Wave Energy ◽  
High Efficiency ◽  
Boundary Integral ◽  
Hydrodynamic Performance ◽  
Chamber Pressure ◽  
Front Wall ◽  
Oscillating Water Column

Abstract Oscillating water column (OWC) wave energy converters are one of the most widely researched devices for ocean wave energy harvesting. This study investigates the hydrodynamic performance of a shore-fixed OWC device for different bottom slopes using two numerical approaches, namely, computational fluid dynamics (CFD) and boundary integral equation method (BIEM). In the BIEM method, the boundary value problem is solved in two-dimensional Cartesian coordinates using the linear water wave theory. The CFD model uses a numerical wave tank (NWT) built using the volume of fluid (VOF) method. Numerical computations are carried out for different sloped bottom geometries and front wall drafts to analyze the hydrodynamic efficiency. There is a general agreement between CFD and BIEM results in terms of resonating behavior of the device. It is observed that the front wall draft has a more significant effect, a lower draft leading to a wider frequency band for optimum conversion at high efficiency. While the BIEM-based analysis resulted in improved performance curve for few of the steeper slopes, the CFD study predicted a lower peak efficiency for the same slopes due to the consideration of real fluid characteristics. Detailed performance comparisons are presented using the time histories of free surface elevation, chamber pressure, and streamlines at different time instants within the OWC chamber.

Numerical investigation of front-wall inclination effects on the hydrodynamic performance of a fixed oscillation water column wave energy converter

2018 ◽  
Vol 233 (2) ◽  
pp. 262-271
Author(s):  
M Anbarsooz ◽  
H Rashki ◽  
A Ghasemi
Keyword(s):  
Water Column ◽  
Wave Height ◽  
Wave Energy ◽  
Nonlinear Waves ◽  
Absorption Efficiency ◽  
Hydrodynamic Performance ◽  
Front Wall ◽  
Oscillating Water Column ◽  
Wave Tank ◽  
Highly Nonlinear

One of the main geometrical parameters of the fixed oscillating water column wave energy converters is the inclination angle of front wall. In this study, the effects of this parameter on the hydrodynamic performance of an oscillating water column is investigated using a fully nonlinear two-dimensional numerical wave tank, which is developed using the Ansys Fluent 15.0 commercial software. The accuracy of the developed wave tank is first examined by simulating an oscillating water column, having a front wall normal to the water-free surface, subjected to linear, small amplitude incident waves. The resultant absorption efficiencies are compared with available analytical data in the literature, where a good agreement was observed. Next, the simulations are performed for strongly nonlinear waves, up to the wave steepness of 0.069 ( H/L = 0.069), where H is the wave height and L is the wave length. Results show that the absorption efficiency of the oscillating water column decreases considerably as the wave height increases. Moreover, the maximum wave energy absorption efficiency for the highly nonlinear waves occurs at a pneumatic damping coefficient lower than that of the linear theory. Then, the absorption efficiency of the oscillating water column is determined for eight various front wall configurations at various incident wave periods. Results show that, the front walls that are slightly bent towards the inner region of the oscillating water column chamber are more efficient at some wave periods in comparison with the cases studied in this paper.

scholarly journals The Influence of the Chamber Configuration on the Hydrodynamic Efficiency of Oscillating Water Column Devices

2020 ◽  
Vol 8 (10) ◽  
pp. 751
Author(s):  
Ayrton Alfonso Medina Rodríguez ◽  
Jesús María Blanco Ilzarbe ◽  
Rodolfo Silva Casarín ◽  
Urko Izquierdo Ereño
Keyword(s):  
Water Column ◽  
Wall Thickness ◽  
Water Waves ◽  
Numerical Results ◽  
Physical Parameters ◽  
Front Wall ◽  
Linear Wave ◽  
Oscillating Water Column ◽  
Wave Regime ◽  
The Impact

Based on the two-dimensional linear wave theory, the effects of the front wall thickness and the bottom profile of an Oscillating Water Column (OWC) device on its efficiency were analyzed. Using the potential flow approach, the solution of the associated boundary value problem was obtained via the boundary element method (BEM). Numerical results for several physical parameters and configurations were obtained. The effects of the front wall thickness on the efficiency are discussed in detail, then, various configurations of the chamber bottom are presented. A wider efficiency band was obtained with a thinner front wall. In a real scenario having a thinner front wall means that such a structure could have less capacity to withstand the impact of storm waves. Applying the model for the case of the Mutriku Wave Energy Plant (MWEP), findings showed that the proposed bottom profiles alter the efficiency curve slightly; higher periods of the incoming water waves were found. This could increase the efficiency of the device in the long-wave regime. Finally, the numerical results were compared with those available in the literature, and were found to be in good agreement.

Numerical Analysis of the Oscillating Water Column (OWC) Wave Energy Converter (WEC) Considering Different Incident Wave Height

2017 ◽  
Vol 370 ◽  
pp. 120-129
Author(s):  
Mateus das Neves Gomes ◽  
Eduardo Alves Amado ◽  
Elizaldo Domingues dos Santos ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha
Keyword(s):  
Water Column ◽  
Wave Height ◽  
Incident Wave ◽  
Wave Energy ◽  
Amplification Factor ◽  
Wave Energy Converter ◽  
Geometric Shape ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Incident Waves

The ocean wave energy conversion into electricity has been increasingly researched in the last years. There are several proposed converters, among them the Oscillating Water Column (OWC) device has been widely studied. The present paper presents a two-dimensional numerical investigation about the fluid dynamics behavior of an OWC Wave Energy Converter (WEC) into electrical energy. The main goal of this work was to numerically analyze the optimized geometric shape obtained in previous work under incident waves with different heights. To do so, the OWC geometric shape was kept constant while the incident wave height was varied. For the numerical solution it was used the Computational Fluid Dynamic (CFD) commercial code FLUENT®, based on the Finite Volume Method (FVM). The multiphasic Volume of Fluid (VOF) model was applied to tackle with the water-air interaction. The computational domain is represented by the OWC device coupled with the wave tank. This work allowed to check the influence of the incident wave height on the hydropneumatic power and the amplification factor of the OWC converter. It was possible to identify that the amplification factor increases as the wave period increases, thereby improving the OWC performance. It is worth to highlight that in the real phenomenon the incident waves on the OWC device have periods, lengths and height variables.

scholarly journals Performance of an U-Shaped Oscillating Water Column Wave Energy Converter Device under Oblique Incident Waves

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 137
Author(s):  
Kshma Trivedi ◽  
Santanu Koley ◽  
Kottala Panduranga
Keyword(s):  
Water Column ◽  
Structural Parameters ◽  
Physical Parameters ◽  
Front Wall ◽  
Angle Of Incidence ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Chamber Length ◽  
Wide Range ◽  
Incident Waves

The present study deals with the performance of an U-shaped oscillating water column device under the action of oblique incident waves. To solve the associated boundary value problem, the dual boundary element method (DBEM) is used. Various physical parameters associated with the U-shaped OWC device, such as the radiation susceptance and conductance coefficients, and the hydrodynamic efficiency, are analyzed for a wide range of wave and structural parameters. The study reveals that the resonance in the efficiency curve occurs for smaller values of wavenumber with an increase in chamber length, submergence depth of the front wall and opening duct, and width of the opening duct. It is observed that with appropriate combinations of the angle of incidence and incident wavenumber, more than 90% efficiency in the U-shaped OWC device can be achieved.

scholarly journals Hydrodynamic performance analysis of a shore fixed oscillating water column wave energy converter in the presence of bottom variations

2019 ◽  
Vol 234 (1) ◽  
pp. 37-47
Author(s):  
Piyush Mohapatra ◽  
Trilochan Sahoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Boundary Integral ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Pressure Jump ◽  
Front Wall ◽  
Oscillating Water Column ◽  
Sea Bed

In this study, the effect of the stepped sea bed on the hydrodynamic performance of an oscillating water column device is investigated using computational fluid dynamics . This investigation is performed in a numerical wave tank modeled using ANSYS Fluent, which incorporates a transient, multiphase volume of fluid method to track the air–water interface. The power take-off unit is modeled as a porous zone in the flow field to produce the pressure jump versus flow characteristics that of a real air turbine. The efficiency of the chamber with and without the stepped bottom is analyzed and compared with known results in the literature. The flow parameters such as the temporal evolution and distribution of the pressure field, velocity field and free surface are studied to understand the performance of the proposed model. The study reveals that there is an improvement in hydrodynamic efficiency with the inclusion of the stepped bottom beneath the oscillating water column chamber, which is in agreement with the previous studies carried out using analytical and boundary integral equation methods. Moreover, the computational fluid dynamics model helps to understand the flow dynamics inside the oscillating water column chamber in a more intricate manner compared to the potential flow-based studies pursued in the literature. The formation of vortices within the oscillating water column chamber, near the front wall and stepped bottom could be captured, which affects the chamber performance to a certain extent. Overall, the study could be useful in the initial design stage of shore fixed oscillating water column devices.

Numerical analysis of the distribution of incident wave energy on an onshore oscillating water column wave energy converter

2017 ◽  
Author(s):  
Lucas Amaral Gaspar ◽  
Paulo Roberto de Freitas Teixeira ◽  
Eric Didier ◽  
Maria da Graça Neves
Keyword(s):  
Numerical Analysis ◽  
Water Column ◽  
Incident Wave ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Incident Wave Energy
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