Design Selection and Geometry in OWC Wave Energy Converters for Performance

Although oscillating water column (OWC) wave energy converters are arguably one of the most studied technologies, it is not clear which chamber geometry, among all of the available alternatives, would provide the best performance at a site of interest. In this work, a numerical model based on the Navier-Stokes equations for two compressible fluids, using a volume-of-fluid interface-capturing approach, is implemented to determine the best performing OWC geometry in a case study off the Port of Vigo (NW Spain). Four general shapes of OWC are analyzed: classic, stepped-bottom, U-shaped and L-shaped, and geometrical variants are investigated. In total, 18 chamber geometries are studied, considering the same turbine geometry in all of them. It was found that the U-shaped and L-shaped designs are the most easily tuned to resonate at a period of interest. Of these two, the L-shaped performs better. The best performance is achieved for an L-shaped OWC design with a shallow entrance, a high horizontal chamber duct and a wide vertical duct, for which a maximum capture-width ratio of 71.6% was achieved.

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Hydrodynamic Modelling of An Oscillating Wave Surge Converter Including Power Take-Off

Journal of Marine Science and Engineering ◽

10.3390/jmse8100771 ◽

2020 ◽

Vol 8 (10) ◽

pp. 771

Author(s):

Daniela Benites-Munoz ◽

Luofeng Huang ◽

Enrico Anderlini ◽

José R. Marín-Lopez ◽

Giles Thomas

Keyword(s):

Wave Energy ◽

Stokes Equations ◽

Three Dimensional ◽

High Amplitude ◽

Realistic Model ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Wave Energy Converters ◽

Fluid Field ◽

Incident Waves

To estimate the response of wave energy converters to different sea environments accurately is an ongoing challenge for researchers and industry, considering that there has to be a balance between guaranteeing their integrity whilst extracting the wave energy efficiently. For oscillating wave surge converters, the incident wave field is changed due to the pitching motion of the flap structure. A key component influencing this motion response is the Power Take-Off system used. Based on OpenFOAM, this paper includes the Power Take-off to establish a realistic model to simulate the operation of a three-dimensional oscillating wave surge converter by solving Reynolds Averaged Navier-Stokes equations. It examines the relationship between incident waves and the perturbed fluid field near the flap, which is of great importance when performing in arrays as neighbouring devices may influence each other. Furthermore, it investigates the influence of different control strategy systems (active and passive) in the energy extracted from regular waves related to the performance of the device. This system is estimated for each wave frequency considered and the results show the efficiency of the energy extracted from the waves is related to high amplitude pitching motions of the device in short periods of time.

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Influences of Recess Geometry and Restrictor Dimension on Flow Patterns and Pressure Distribution of Hydrostatic Bearings

Volume 5: Turbo Expo 2007 ◽

10.1115/gt2007-28219 ◽

2007 ◽

Cited By ~ 2

Author(s):

Cheng-Hsien Chen ◽

Yuan Kang ◽

Yeon-Pun Chang ◽

De-Xing Peng ◽

Ding-Wen Yang

Keyword(s):

Pressure Distribution ◽

Stokes Equations ◽

Flow Patterns ◽

Lubricant Film ◽

Navier Stokes ◽

Width Ratio ◽

Navier Stokes Equations ◽

Hydrostatic Bearing ◽

Lubricant Flow ◽

Land Width

This paper studies the influences of recess geometry and restrictor dimensions on the flow patterns and pressure distribution of lubricant film, which are coupled effects of hybrid characteristics of a hydrostatic bearing. The lubricant flow is described by using the Navier-Stokes equations. The Galerkin weighted residual finite element method is applied to determine the lubricant velocities and pressure in the bearing clearance. The numerical simulations will evaluate the effects of the land-width ratio and restriction parameter as well as the influence of modified Reynolds number and the jet-strength coefficient on the flow patterns in the recess and pressure distribution in lubricant film. On the basis of the simulation drawn from this study, the simulated results are expected to help engineers make better use of the design of hydrostatic bearing and its restrictors.

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Sequential Monte Carlo Methods for High-Dimensional Inverse Problems: A Case Study for the Navier--Stokes Equations

SIAM/ASA Journal on Uncertainty Quantification ◽

10.1137/130930364 ◽

2014 ◽

Vol 2 (1) ◽

pp. 464-489 ◽

Cited By ~ 24

Author(s):

Nikolas Kantas ◽

Alexandros Beskos ◽

Ajay Jasra

Keyword(s):

Monte Carlo ◽

Inverse Problems ◽

Monte Carlo Methods ◽

Sequential Monte Carlo ◽

Stokes Equations ◽

Navier Stokes ◽

High Dimensional ◽

Sequential Monte Carlo Methods ◽

Navier Stokes Equations

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Integration of Marine Wave Energy Converters into Seaports: A Case Study in the Port of Valencia

Energies ◽

10.3390/en12050787 ◽

2019 ◽

Vol 12 (5) ◽

pp. 787 ◽

Cited By ~ 14

Author(s):

Raúl Cascajo ◽

Emilio García ◽

Eduardo Quiles ◽

Antonio Correcher ◽

Francisco Morant

Keyword(s):

Wave Energy ◽

Energy Demand ◽

Energy Potential ◽

Wave Energy Converters ◽

Wave Power Potential ◽

A Prospective Study ◽

Different Sources ◽

New Infrastructure ◽

Energy Converters

A feasibility study for the installation of Wave Energy Converters (WEC) in a Spanish Mediterranean port is evaluated in this paper. The final aim is to evaluate the possibility of building a new infrastructure which combines a breakwater and a WEC able to provide energy to the commercial port of Valencia. An estimation of the wave power potential is made according to existing databases from different sources. A review of the existing WEC types is carried out in order to choose the most suitable technology for its installation in a port environment. The authors discuss the main advantages and issues of the integration of WEC in port breakwaters. A prospective study for the Port of Valencia is made, considering the port energy demand evolution, historical data on wave energy potential and the port expansion plans. We conclude that Overtopping Devices (OTDs) are the most suitable ones to allow the good integration with the new breakwater needed for the expansion of the Port of Valencia and we give an estimation on the power available from the resource in our case study.

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Regression Diagnostics with Predicted Residuals of Linear Model with Improved Singular Value Classification Applied to Forecast the Hydrodynamic Efficiency of Wave Energy Converters

Applied Sciences ◽

10.3390/app11072990 ◽

2021 ◽

Vol 11 (7) ◽

pp. 2990

Author(s):

Kiril Tenekedjiev ◽

Nagi Abdussamie ◽

Hyunbin An ◽

Natalia Nikolova

Keyword(s):

Linear Regression ◽

Wave Energy ◽

Singular Value ◽

Design Parameters ◽

Hydrodynamic Efficiency ◽

Wave Energy Converters ◽

Modified Algorithm ◽

Mlr Model ◽

Energy Converters

In the preliminary stages of design of the oscillating water column (OWC) type of wave energy converters (WECs), we need a reliable cost- and time-effective method to predict the hydrodynamic efficiency as a function of the design parameters. One of the cheapest approaches is to create a multiple linear regression (MLR) model using an existing data set. The problem with this approach is that the reliability of the MLR predictions depend on the validity of the regression assumptions, which are either rarely tested or tested using sub-optimal procedures. We offer a series of novel methods for assumption diagnostics that we apply in our case study for MLR prediction of the hydrodynamics efficiency of OWC WECs. Namely, we propose: a novel procedure for reliable identification of the zero singular values of a matrix; a modified algorithm for stepwise regression; a modified algorithm to detect heteroskedasticity and identify statistically significant but practically insignificant heteroscedasticity in the original model; a novel test of the validity of the nullity assumption; a modified Jarque–Bera Monte Carlo error normality test. In our case study, the deviations from the assumptions of the classical normal linear regression model were fully diagnosed and dealt with. The newly proposed algorithms based on improved singular value decomposition (SVD) of the design matrix and on predicted residuals were successfully tested with a new family of goodness-of-fit measures. We empirically investigated the correct placement of an elaborate outlier detection procedure in the overall diagnostic sequence. As a result, we constructed a reliable MLR model to predict the hydrodynamic efficiency in the preliminary stages of design. MLR is a useful tool at the preliminary stages of design and can produce highly reliable and time-effective predictions of the OWC WEC performance provided that the constructing and diagnostic procedures are modified to reflect the latest advances in statistics. The main advantage of MLR models compared to other modern black box models is that their assumptions are known and can be tested in practice, which increases the reliability of the model predictions.

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Nexus water & energy: a case study of wave energy converters (WECs) to desalination applications in Sicily

International Journal of Heat and Technology ◽

10.18280/ijht.34sp0227 ◽

2016 ◽

Vol 34 (Special Issue 2) ◽

pp. S379-S386 ◽

Cited By ~ 14

Author(s):

Alessia Viola ◽

Vincenzo Franzitta ◽

Marco Trapanese ◽

Domenico Curto

Keyword(s):

Wave Energy ◽

Wave Energy Converters ◽

Energy Converters

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Parametric Study of a Symmetric Flow Distributor

Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C ◽

10.1115/imece2009-11149 ◽

2009 ◽

Author(s):

Bladimir Ramos-Alvarado ◽

Abel Hernandez-Guerrero ◽

Daniel Juarez-Robles ◽

Peiwen Li ◽

J. C. Rubio-Arana

Keyword(s):

Parametric Study ◽

Stokes Equations ◽

Flow Behavior ◽

Flow Distribution ◽

Navier Stokes ◽

Width Ratio ◽

Symmetric Flow ◽

Navier Stokes Equations ◽

Advantages And Disadvantages ◽

Flow Distributor

A parametric study was conducted in order to reduce the pressure drop and to improve the uniformity of flow distribution in a symmetric flow distributor. A CFD model was employed to simulate the flow behavior by solving the Navier-Stokes equations in a complete 3D model. The present work is a complete parametric study of a base model, reported in previous studies, but keeping the same flow pattern. To improve the performance of the base design, three known successive parametric ratios, as functions of the hydraulic diameters of the channels, were tested in order to study the advantages and disadvantages of each one in terms of two dimensionless parameters that measure the uniformity of flow distribution. A remarkable improvement in the performance of the base model was achieved by modifying the width ratio of the channels. The present work is a contribution to the study of flow distributors to be used as heat exchangers, PEMFC flow channels and other flow devices.

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