Academic literature on the topic 'Oscillating Surge Wave Energy Converter (OSWEC)'
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Journal articles on the topic "Oscillating Surge Wave Energy Converter (OSWEC)"
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Balitsky, Philip, Nicolas Quartier, Gael Verao Fernandez, Vasiliki Stratigaki, and Peter Troch. "Analyzing the Near-Field Effects and the Power Production of an Array of Heaving Cylindrical WECs and OSWECs Using a Coupled Hydrodynamic-PTO Model." Energies 11, no. 12 (2018): 3489. http://dx.doi.org/10.3390/en11123489.
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The Power Take-Off (PTO) system is the key component of a Wave Energy Converter (WEC) that distinguishes it from a simple floating body because the uptake of the energy by the PTO system modifies the wave field surrounding the WEC. Consequently, the choice of a proper PTO model of a WEC is a key factor in the accuracy of a numerical model that serves to validate the economic impact of a wave energy project. Simultaneously, the given numerical model needs to simulate many WEC units operating in close proximity in a WEC farm, as such conglomerations are seen by the wave energy industry as the path to economic viability. A balance must therefore be struck between an accurate PTO model and the numerical cost of running it for various WEC farm configurations to test the viability of any given WEC farm project. Because hydrodynamic interaction between the WECs in a farm modifies the incoming wave field, both the power output of a WEC farm and the surface elevations in the ‘near field’ area will be affected. For certain types of WECs, namely heaving cylindrical WECs, the PTO system strongly modifies the motion of the WECs. Consequently, the choice of a PTO system affects both the power production and the surface elevations in the ‘near field’ of a WEC farm. In this paper, we investigate the effect of a PTO system for a small wave farm that we term ‘WEC array’ of 5 WECs of two types: a heaving cylindrical WEC and an Oscillating Surge Wave Energy Converter (OSWEC). These WECs are positioned in a staggered array configuration designed to extract the maximum power from the incident waves. The PTO system is modelled in WEC-Sim, a purpose-built WEC dynamics simulator. The PTO system is coupled to the open-source wave structure interaction solver NEMOH to calculate the average wave field η in the ‘near-field’. Using a WEC-specific novel PTO system model, the effect of a hydraulic PTO system on the WEC array power production and the near-field is compared to that of a linear PTO system. Results are given for a series of regular wave conditions for a single WEC and subsequently extended to a 5-WEC array. We demonstrate the quantitative and qualitative differences in the power and the ‘near-field’ effects between a 5-heaving cylindrical WEC array and a 5-OSWEC array. Furthermore, we show that modeling a hydraulic PTO system as a linear PTO system in the case of a heaving cylindrical WEC leads to considerable inaccuracies in the calculation of average absorbed power, but not in the near-field surface elevations. Yet, in the case of an OSWEC, a hydraulic PTO system cannot be reduced to a linear PTO coefficient without introducing substantial inaccuracies into both the array power output and the near-field effects. We discuss the implications of our results compared to previous research on WEC arrays which used simplified linear coefficients as a proxy for PTO systems.
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Li, Qiaofeng, Jia Mi, Xiaofan Li, Shuo Chen, Boxi Jiang, and Lei Zuo. "A self-floating oscillating surge wave energy converter." Energy 230 (September 2021): 120668. http://dx.doi.org/10.1016/j.energy.2021.120668.
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Apolonia, Maria, and Teresa Simas. "Life Cycle Assessment of an Oscillating Wave Surge Energy Converter." Journal of Marine Science and Engineering 9, no. 2 (2021): 206. http://dx.doi.org/10.3390/jmse9020206.
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So far, very few studies have focused on the quantification of the environmental impacts of a wave energy converter. The current study presents a preliminary Life Cycle Assessment (LCA) of the MegaRoller wave energy converter, aiming to contribute to decision making regarding the least carbon- and energy-intensive design choices. The LCA encompasses all life cycle stages from “cradle-to-grave” for the wave energy converter, including the panel, foundation, PTO and mooring system, considering its deployment in Peniche, Portugal. Background data was mainly sourced from the manufacturer whereas foreground data was sourced from the Ecoinvent database (v.3.4). The resulting impact assessment of the MegaRoller is aligned with all previous studies in concluding that the main environmental impacts are due to materials use and manufacture, and mainly due to high amounts of material used, particularly steel. The scenario analysis showed that a reduction of the environmental impacts in the final design of the MegaRoller wave energy converter could potentially lie in reducing the quantity of steel by studying alternatives for its replacement. Results are generally comparable with earlier studies for ocean technologies and are very low when compared with other power generating technologies.
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Balitsky, Philip, Nicolas Quartier, Vasiliki Stratigaki, Gael Verao Fernandez, Panagiotis Vasarmidis, and Peter Troch. "Analysing the Near-Field Effects and the Power Production of Near-Shore WEC Array Using a New Wave-to-Wire Model." Water 11, no. 6 (2019): 1137. http://dx.doi.org/10.3390/w11061137.
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In this study, a series of modules is integrated into a wave-to-wire (W2W) model that links a Boundary Element Method (BEM) solver to a Wave Energy Converter (WEC) motion solver which are in turn coupled to a wave propagation model. The hydrodynamics of the WECs are resolved in the wave structure interaction solver NEMOH, the Power Take-off (PTO) is simulated in the WEC simulation tool WEC-Sim, and the resulting perturbed wave field is coupled to the mild-slope propagation model MILDwave. The W2W model is run for verified for a realistic wave energy project consisting of a WEC farm composed of 10 5-WEC arrays of Oscillating Surging Wave Energy Converters (OSWECs). The investigated WEC farm is modelled for a real wave climate and a sloping bathymetry based on a proposed OSWEC array project off the coast of Bretagne, France. Each WEC array is arranged in a power-maximizing 2-row configuration that also minimizes the inter-array separation distance d x and d y and the arrays are located in a staggered energy maximizing configuration that also decreases the along-shore WEC farm extent. The WEC farm power output and the near and far-field effects are simulated for irregular waves with various significant wave heights wave peak periods and mean wave incidence directions β based on the modelled site wave climatology. The PTO system of each WEC in each farm is modelled as a closed-circuit hydraulic PTO system optimized for each set of incident wave conditions, mimicking the proposed site technology, namely the WaveRoller® OSWEC developed by AW Energy Ltd. The investigation in this study provides a proof of concept of the proposed W2W model in investigating potential commercial WEC projects.
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Tom, N. M., M. J. Lawson, Y. H. Yu, and A. D. Wright. "Development of a nearshore oscillating surge wave energy converter with variable geometry." Renewable Energy 96 (October 2016): 410–24. http://dx.doi.org/10.1016/j.renene.2016.04.016.
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Tom, Nathan, Michael Lawson, Yi-Hsiang Yu, and Alan Wright. "Spectral modeling of an oscillating surge wave energy converter with control surfaces." Applied Ocean Research 56 (March 2016): 143–56. http://dx.doi.org/10.1016/j.apor.2016.01.006.
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Benites-Munoz, Daniela, Luofeng Huang, Enrico Anderlini, José R. Marín-Lopez, and Giles Thomas. "Hydrodynamic Modelling of An Oscillating Wave Surge Converter Including Power Take-Off." Journal of Marine Science and Engineering 8, no. 10 (2020): 771. http://dx.doi.org/10.3390/jmse8100771.
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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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Liu, Zhenqing, Yize Wang, and Xugang Hua. "Prediction and optimization of oscillating wave surge converter using machine learning techniques." Energy Conversion and Management 210 (April 2020): 112677. http://dx.doi.org/10.1016/j.enconman.2020.112677.
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Cheng, Yong, Chen Xi, Saishuai Dai, Chunyan Ji, and Margot Cocard. "Wave energy extraction for an array of dual-oscillating wave surge converter with different layouts." Applied Energy 292 (June 2021): 116899. http://dx.doi.org/10.1016/j.apenergy.2021.116899.
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Choiniere, Michael A., Nathan M. Tom, and Krish P. Thiagarajan. "Load shedding characteristics of an oscillating surge wave energy converter with variable geometry." Ocean Engineering 186 (August 2019): 105982. http://dx.doi.org/10.1016/j.oceaneng.2019.04.063.
Full textDissertations / Theses on the topic "Oscillating Surge Wave Energy Converter (OSWEC)"
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Capper, Joseph David. "Numerical Analysis and Parameter Optimization of Portable Oscillating-Body Wave Energy Converters." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103861.
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As a clean, abundant, and renewable source of energy with a strategic location in close proximity to global population regions, ocean wave energy shows major promise. Although much wave energy converter development has focused on large-scale power generation, there is also increasing interest in small-scale applications for powering the blue economy. In this thesis, the objective was to optimize the performance of small-sized, portable, oscillating-body wave energy converters (WECs). Two types of oscillating body WECs were studied: bottom hinged and two-body attenuator. For the bottom-hinged device, the goal was to show the feasibility of an oscillating surge WEC and desalination system using numerical modeling to estimate the system performance. For a 5-day test period, the model estimated 517 L of freshwater production with 711 ppm concentration and showed effective brine discharge, agreeing well with preliminary experimental results.
The objective for the two-body attenuator was to develop a method of power maximization through resonance tuning and numerical simulation. Three different geometries of body cross sections were used for the study with four different drag coefficients for each geometry. Power generation was maximized by adjusting body dimensions to match the natural frequency with the wave frequency. Based on the time domain simulation results, there was not a significant difference in power between the geometries when variation in drag was not considered, but the elliptical geometry had the highest power when using approximate drag coefficients. Using the two degree-of-freedom (2DOF) model with approximate drag coefficients, the elliptical cross section had a max power of 27.1 W and 7.36% capture width ratio (CWR) for regular waves and a max power of 8.32 W and 2.26% CWR for irregular waves. Using the three degree-of-freedom (3DOF) model with approximate drag coefficients, the elliptical cross section had a max power of 22.5 W and 6.12% CWR for regular waves and 6.18 W and 1.68% CWR for irregular waves. A mooring stiffness study was performed with the 3DOF model, showing that mooring stiffness can be increased to increase relative motion and therefore increase power.<br>Master of Science<br>As a clean, abundant, and renewable source of energy with a strategic location in close proximity to global population centers, ocean wave energy shows major promise. Although much wave energy converter development has focused on large-scale power generation, there is also increasing interest in small-scale applications for powering the blue economy. There are many situations where large-scale wave energy converter (WEC) devices are not necessary or practical, but easily-portable, small-sized WECs are suitable, including navigation signs, illumination, sensors, survival kits, electronics charging, and portable desalination. In this thesis, the objective was to optimize the performance of small-sized, oscillating body wave energy converters. Oscillating body WECs function by converting a device's wave-driven oscillating motion into useful power. Two types of oscillating body WECs were studied: bottom hinged and two-body attenuator. For the bottom-hinged device, the goal was to show the feasibility of a WEC and desalination system using numerical modeling to estimate the system performance. Based on the model results, the system will produce desirable amounts of fresh water with suitably low concentration and be effective at discharging brine. The objective for the two-body attenuator was to develop a method of power maximization through resonance tuning and numerical simulation. Based on the two- and three-degree-of-freedom model results with approximate drag coefficients, the elliptical cross section had the largest power absorption out of three different geometries of body cross sections. A mooring stiffness study with the three-degree-of-freedom model showed that mooring stiffness can be increased to increase power absorption.
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Bocking, Bryce. "Numerical and experimental modelling of an oscillating wave surge converter in partially standing wave systems." Thesis, 2017. https://dspace.library.uvic.ca//handle/1828/8802.
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In the field of ocean wave energy converters (WECs), active areas of research are on a priori or in situ methods for power production estimates and on control system design. Linear potential flow theory modelling techniques often underpin these studies; however, such models rely upon small wave and body motion amplitude assumptions and therefore cannot be applied to all wave conditions. Nonlinear extensions can be applied to the fluid loads upon the structure to extend the range of wave conditions for which these models can provide accurate predictions. However, careful consideration of the thresholds of wave height and periods to which these models can be applied is still required. Experimental modelling in wave tank facilities can be used for this purpose by comparing experimental observations to numerical predictions using the experimental wave field as an input.
This study establishes a recommended time domain numerical modeling approach for power production assessments of oscillating wave surge converters (OWSCs), a class of WEC designed to operate in shallow and intermediate water depths. Three candidate models were developed based on nonlinear numerical modelling techniques in literature, each with varying levels of complexity. Numerical predictions provided by each model were found to be very similar for small wave amplitudes, but divergence between the models was observed as wave height increased.
Experimental data collected with a scale model OWSC for a variety of wave conditions was used to evaluate the accuracy of the candidate models. These experiments were conducted in a small-scale wave flume at the University of Victoria. A challenge with this experimental work was managing wave reflections from the boundaries of the tank, which were significant and impacted the dynamics of the scale model OWSC. To resolve this challenge, a modified reflection algorithm based upon the Mansard and Funke method was created to identify the incident and reflected wave amplitudes while the OWSC model is in the tank. Both incident and reflected wave amplitudes are then input to the candidate models to compare numerical predictions with experimental observations.
The candidate models agreed reasonably well with the experimental data, and demonstrated the utility of the modified wave reflection algorithm for future experiments. However, the maximum wave height generated in the wave tank was found to be limited by the stroke length of the wavemaker. As a result, no significant divergence of the candidate model predictions from the experimental data could be observed for the limited range of wave conditions, and therefore a recommended model could not be selected based solely on the experimental/numerical model comparisons.
Preliminary assessments of the annual power production (APP) for the OWSC were obtained for a potential deployment site on the west coast of Vancouver Island. Optimal power take-off (PTO) settings for the candidate models were identified using a least-squares optimization to maximize power production for a given set of wave conditions. The power production of the OWSC at full scale was then simulated for each bin of a wave histogram representing one year of sea states at the deployment site. Of the three candidate models, APP estimates were only obtained for Model 1, which has the lowest computational requirements, and Model 3, which implements the most accurate algorithm for computing the fluid loads upon the OWSC device. Model 2 was not considered as it provides neither advantages of Models 1 and 3.
The APP estimates from Models 1 and 3 were 337 and 361 MWh per year. For future power production assessments, Model 3 is recommended due to its more accurate model of the fluid loads upon the OWSC. However, if the high computational requirements of Model 3 are problematic, then Model 1 can be used to obtain a slightly conservative estimate of APP with a much lower computational effort.<br>Graduate
Conference papers on the topic "Oscillating Surge Wave Energy Converter (OSWEC)"
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Yu, Yi-Hsiang, Ye Li, Kathleen Hallett, and Chad Hotimsky. "Design and Analysis for a Floating Oscillating Surge Wave Energy Converter." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24511.
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This paper presents a recent study on the design and analysis of an oscillating surge wave energy converter (OSWEC). A successful wave energy conversion design requires balance between the design performance and cost. The cost of energy is often used as the metric to judge the design of the wave energy conversion (WEC) system, which is often determined based on the device’s power performance; the cost of manufacturing, deployment, operation, and maintenance; and environmental compliance. The objective of this study is to demonstrate the importance of a cost-driven design strategy and how it can affect a WEC design. A set of three oscillating surge wave energy converter designs was analyzed and used as examples. The power generation performance of the design was modeled using a time-domain numerical simulation tool, and the mass properties of the design were determined based on a simple structure analysis. The results of those power performance simulations, the structure analysis, and a simple economic assessment were then used to determine the cost-efficiency of selected OSWEC designs. Finally, we present a discussion on the environmental barrier, integrated design strategy, and the key areas that need further investigation.
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Tom, Nathan M., Yi-Hsiang Yu, Alan D. Wright, and Michael Lawson. "Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-55046.
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The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.
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Crooks, David, Jos van ’t Hoff, Matt Folley, and Bjoern Elsaesser. "Oscillating Wave Surge Converter Forced Oscillation Tests." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54660.
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Hydrodynamic numerical models of Wave Energy Converters (WEC) contain hydrodynamic coefficients that are commonly obtained from numerical codes that solve linear potential flow problems using Boundary Element Methods (BEM codes). The assumptions made by the BEM codes in their calculation of the linear hydrodynamic coefficients are violated by the large and nonlinear motions that wave activation body class WECs often go through during operation. In this study, Forced Oscillation Tests were used to evaluate the hydrodynamic torque coefficients estimated for an Oscillating Wave Surge Converter (OWSC) WEC by two BEM codes; WAMIT and Nemoh. The paper describes the tests and the active Force Feedback Dynamometer test rig used to perform them. The results indicate good agreement between the BEM codes and experimental data for small angular displacement amplitude oscillations, as expected; up to 0.3 rad. The torque not predicted by the BEM codes is presented and shown to have an amplitude and phase that vary throughout the range of tests performed.
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Wei, Yanji, Ashkan Rafiee, Bjoern Elsaesser, and Frederic Dias. "Numerical Simulation of an Oscillating Wave Surge Converter." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10189.
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It has been known that bottom hinged Oscillating Wave Surge Converters (OWSCs) are an efficient way of extracting power from ocean waves (Whittaker et al. 2007). OWSCs are in general large buoyant flaps, hinged at the bottom of the ocean and oscillating back and forth under the action of incoming incident waves (Schmitt et al. 2012, Renzi and Dias 2012). The oscillating motion is then converted into energy by pumping high-pressure water to drive a hydro–electric turbine. This paper deals with numerical studies of wave loading on an OWSC using the FLUENT software. In numerical simulation of wave loading on an OWSC using mesh-based methods, the mesh around the flap is required to be updated frequently. This is due to the large amplitude rotation of the OWSC around the hinge. In this work, the remeshing was achieved by using the so-called dynamic mesh approach built in FLUENT. Furthermore, the motion of the OWSC is updated in time using a fourth order multi point time integration scheme coupled with the flow solver. The results for the flap motion and the excited torque on the hinged position were compared with experimental data obtained in a wave tank at Queen’s University of Belfast. The results showed the capability of the numerical model with a dynamic mesh approach in modeling large amplitude motions of the flap. In addition, the pressures at various locations on the flap were compared with the experimental measurements in order to demonstrate the accuracy of the proposed model in capturing local features of the flow as well as the global features.
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Xu, Chuanchao, Xiangnan Wang, and Zhenyuan Wang. "Experimental Study on the Dynamics of A Bottom-hinged Oscillating Wave Surge Converter." In 2016 5th International Conference on Sustainable Energy and Environment Engineering (ICSEEE 2016). Atlantis Press, 2016. http://dx.doi.org/10.2991/icseee-16.2016.38.
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Sarkar, Dripta, Emiliano Renzi, and Frederic Dias. "Wave Power Extraction by an Oscillating Wave Surge Converter in Random Seas." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10188.
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This paper investigates the behaviour of a bottom hinged flap-type wave energy converter (WEC), namely the Oscillating Wave Surge Converter (OWSC), in random seas. The semi-analytical model of Renzi and Dias (2013b) for an OWSC in the open ocean is considered to analyze the performance of the device in random incident waves. The modelling is performed within the framework of a linear potential flow theory, by means of Green’s integral theorem. The resultant hypersingular integral equation for the velocity potential obtained from the above formulation is solved using a series expansion in terms of Chebyshev polynomials of the second kind. The behaviour of the device is investigated for six different sea states, generally representative of the wave climate in the North Atlantic Ocean at the European Marine Energy Centre test site. A Bretschneider spectrum is considered in order to reproduce the sea climate. The analysis is made for sea states where the spectral energy contribution from large periods, which cause excitation of body resonance of the flap — not modelled by the linear theory — is almost negligible. The power take-off damping is optimised for each individual sea state to calculate the captured power. The investigation is undertaken for two flaps of different widths, resembling the Oyster1 and the new Oyster800 version of the Oyster WEC, respectively. Comparison is made between the performances of the two converters. The effect of varying the width and the characteristic parameters of the flap on the capture factor in random seas is then discussed. The results of the analysis show that the performance of the device is fairly consistent for the sea states considered. Also an enhancement in the overall average capture factor is shown for the latest version of the wave energy conversion device.
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Moretti, Giacomo, David Forehand, Rocco Vertechy, Marco Fontana, and David Ingram. "Modeling of an Oscillating Wave Surge Converter With Dielectric Elastomer Power Take-Off." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23559.
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This paper introduces a novel concept of Oscillating Wave Surge Converter, named Poly-Surge, provided with a Dielectric Elastomer Generator (DEG) as Power Take-Off (PTO) system. DEGs are transducers that employ rubber-like polymers to conceive deformable membrane capacitors capable of directly converting mechanical energy into electricity. In particular, a Parallelogram Shaped DEG is considered. In the paper, a description of the Poly-Surge is outlined and engineering considerations about the operation and control of the device are presented. In addition, a mathematical model of the system is provided. Linear time-domain hydrodynamics is assumed for the primary interface, while a non linear electro-hyperelastic model is employed for the DEG PTO. A design approach for the Poly-Surge DEG PTO is introduced which aims at maximizing the energy produced in a year by the device in a reference wave climate, defined by a set of equivalent monochromatic wave conditions. A comparison is done with two other WEC models that employ the same primary interface but are equipped with mathematically linear PTO systems under optimal and suboptimal control. The results show promising performance of annual energy productivity, with slightly reduced values for the Poly-Surge, even if a very basic architecture and control strategy are assumed.
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da Silva, Leandro S. P., Nataliia Y. Sergiienko, Benjamin S. Cazzolato, Boyin Ding, Celso P. Pesce, and Helio M. Morishita. "Nonlinear Analysis of an Oscillating Wave Surge Converter in Frequency Domain via Statistical Linearization." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18510.
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Abstract Wave energy devices operate in resonant conditions to optimize power absorption, which leads to large displacements. As a result, nonlinearities play an important role in the system dynamics and must be accounted for in the numerical models for realistic prediction of the power generated. In general, time domain (TD) simulations are employed to capture the effects of the nonlinearities. However, the computational cost associated with these simulations is considerably higher compared to linear frequency domain (FD) methods. In this regard, the following work deals with the nonlinear analysis of an oscillating wave surge converter (OWSC) in the FD via the statistical linearization (SL) technique. Four nonlinearities for the proposed device are addressed: Coulomb-like torque regulated by the direction of motion, viscous drag torque, nonlinear buoyant net torque, and parametric excitation torque modulated by the flap angle. The reliability of the SL technique is compared with nonlinear TD simulations in terms of response probability distribution and power spectrum density (PSD) of the response and torque; and mean power produced. The results have demonstrated a good agreement between TD simulations and SL, while the computation time of the SL model is approximately 3 orders of magnitude faster. As a result, SL is a valuable tool to assess the OWSC performance under various wave scenarios over a range of design parameters, and can assist the development of such wave energy converters (WECs).
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Henry, Alan, Thomas Abadie, Jonathan Nicholson, Alan McKinley, Olivier Kimmoun, and Frederic Dias. "The Vertical Distribution and Evolution of Slam Pressure on an Oscillating Wave Surge Converter." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41290.
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The accurate definition of the extreme wave loads which act on offshore structures represents a significant challenge for design engineers and even with decades of empirical data to base designs upon there are still failures attributed to wave loading. The environmental conditions which cause these loads are infrequent and highly non-linear which means that they are not well understood or simple to describe. If the structure is large enough to affect the incident wave significantly further non-linear effects can influence the loading. Moreover if the structure is floating and excited by the wave field then its responses, which are also likely to be highly non-linear, must be included in the analysis. This makes the description of the loading on such a structure difficult to determine and the design codes will often suggest employing various tools including small scale experiments, numerical and analytical methods, as well as empirical data if available. Wave Energy Converters (WECs) are a new class of offshore structure which pose new design challenges, lacking the design codes and empirical data found in other industries. These machines are located in highly exposed and energetic sites, designed to be excited by the waves and will be expected to withstand extreme conditions over their 25 year design life. One such WEC is being developed by Aquamarine Power Ltd and is called Oyster. Oyster is a buoyant flap which is hinged close to the seabed, in water depths of 10 to 15m, piercing the water surface. The flap is driven back and forth by the action of the waves and this mechanical energy is then converted to electricity. It has been identified in previous experiments that Oyster is not only subject to wave impacts but it occasionally slams into the water surface with high angular velocity. This slamming effect has been identified as an extreme load case and work is ongoing to describe it in terms of the pressure exerted on the outer skin and the transfer of this short duration impulsive load through various parts of the structure. This paper describes a series of 40th scale experiments undertaken to investigate the pressure on the face of the flap during the slamming event. A vertical array of pressure sensors is used to measure the pressure exerted on the flap. Characteristics of the slam pressure such as the rise time, magnitude, spatial distribution and temporal evolution are revealed. Similarities are drawn between this slamming phenomenon and the classical water entry problems, such as ship hull slamming. With this similitude identified, common analytical tools are used to predict the slam pressure which is compared to that measured in the experiment.
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Falnes, Johannes. "Wave-Energy Conversion Avoiding Destructive Wave Interference." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62617.
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Many of the various proposed wave-energy converter (WEC) units are immersed oscillating bodies, which, in the primary conversion stage, collect input power as the product of two oscillating factors, a velocity and wave-induced force. The latter factor is vulnerable to destructive wave interference, unless the extension of each WEC unit is sufficiently small. Two simple, elementary-mathematical, inequalities express two kinds of upper bounds for the wave power that may be absorbed by an oscillating immersed body. The first upper bound, published in the mid 1970s, is well-known, in contrast to the second one, Budal’s upper bound, which was derived a few years later, and which takes the WEC’s hull volume into consideration. Combining the two different upper bounds and considering also a typical wave climate, we may conclude that for a WEC array plant deployed in the North Atlantic, each point-absorber WEC unit volume should typically be about 300 cubic metre, and its primary-converted power take-off (PTO) capacity should be in the range of 50 to 300 kW. These heaving WEC units, being monopole wave radiators, may have a much higher PTO-capacity-to-immersed-hull-wet-surface ratio than any other type of WEC unit, such as those using dipole-mode (e.g. surge- or pitch-mode) radiation. For large-scale utilization of wave energy, arrays of WEC units are required.
Reports on the topic "Oscillating Surge Wave Energy Converter (OSWEC)"
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Yu, Y. H., D. S. Jenne, R. Thresher, A. Copping, S. Geerlofs, and L. A. Hanna. Reference Model 5 (RM5): Oscillating Surge Wave Energy Converter. Office of Scientific and Technical Information (OSTI), 2015. http://dx.doi.org/10.2172/1169778.
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Ruehl, Kelley, Giorgio Bacelli, and Budi Gunawan. Experimental Testing of a Floating Oscillating Surge Wave Energy Converter. Office of Scientific and Technical Information (OSTI), 2019. http://dx.doi.org/10.2172/1761877.
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