Efficient determination of nonlinear response of an array of Oscillating Water Column energy harvesters exposed to random sea waves

Abstract The sea is an important renewable energy resource for its extension and the power conveyed by waves, currents, tides, and thermal gradients. Amongst these physical phenomena, sea waves are the source with the highest energy density and may contribute to fulfilling the global increase of power demand. Despite the potential of sea waves, their harnessing is still a technological challenge. Oscillating water column systems operating with Wells turbines represent one of the most straightforward and reliable solutions for the optimal exploitation of this resource. An analytical model and computational fluid dynamics models were developed to evaluate the functioning of monoplane isolated Wells turbines. For the former modeling typology, a blade element momentum code relying on the actuator disk theory was applied, considering the rotor as a set of airfoils. For the latter modeling typology, a three-dimensional multi-block technique was implemented to create the computational domain with a fully mapped mesh composed of hexahedral elements. The employment of circumferential periodic boundary conditions allowed for the reduction of computational power and time. The models use Reynolds-averaged Navier-Stokes (RANS) or u-RANS schemes with a multiple reference frame approach or the u-RANS formulation with a sliding mesh approach. The achieved results were compared with analytical and experimental literature data for validation. All the developed models showed good agreement. The analytical model is suitable for a fast prediction of the turbine operation on a wide set of configurations during the first design stages, while the computational fluid dynamics (CFD) models are indicated for the further investigation of the selected configurations.

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Wave power extraction from an oscillating water column at the tip of a breakwater

Journal of Fluid Mechanics ◽

10.1017/s0022112009005990 ◽

2009 ◽

Vol 626 ◽

pp. 395-414 ◽

Cited By ~ 77

Author(s):

HERVÉ MARTINS-RIVAS ◽

CHIANG C. MEI

Keyword(s):

Water Column ◽

Angle Of Incidence ◽

Oscillating Water Column ◽

Sea Waves ◽

Power Extraction ◽

Grid Connection ◽

Simple Geometry ◽

Construction Operation ◽

The Waves ◽

Extracted Power

To reduce the costs of construction, operation, maintenance, energy storage and grid connection, some devices for extracting energy from sea waves are likely to be installed on the coast. We study theoretically a single oscillating water column (OWC) installed at the tip of a long and thin breakwater. The linearized problems of radiation and scattering for a hollow cylinder with an open bottom are then solved by the usual method of eigenfunction expansions and integral equations. Since a thin breakwater is the limit of a wedge, an exact solution for the diffraction by a solid cylinder at the tip of a wedge is derived to facilitate the analysis. Following Sarmento & Falcão (J. Fluid Mech., vol. 150, 1985, pp. 467–485), power takeoff by Wells turbines is modelled by including air compressibility in the chamber above the water surface. The effects of air compressibility on the extraction efficiency is studied. It is shown that for this simple geometry the angle of incidence affects the waves outside the structure but not the extracted power.

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Efficient Nonlinear Response Determination of an Array of Owc Energy Harvesters

10.1115/1.0001128v ◽

2021 ◽

Author(s):

Giovanni Malara ◽

Pol Spanos

Keyword(s):

Nonlinear Response ◽

Energy Harvesters ◽

Response Determination

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Response Statistics of U-Oscillating Water Column Energy Harvesters Exposed to Extreme Storms: Application to the Case Study of Roccella Jonica (Italy)

ASCE-ASME J Risk and Uncert in Engrg Sys Part B Mech Engrg ◽

10.1115/1.4049210 ◽

2020 ◽

Author(s):

Felice Arena ◽

Valentina Laface ◽

Giovanni Malara ◽

Saveria Meduri ◽

Andrea Pedroncini

Keyword(s):

Water Column ◽

Wave Energy ◽

Environmental Conditions ◽

Extreme Event ◽

Time History ◽

Structural Safety ◽

Sea Waves ◽

Energy Harvesters ◽

Storm Model

Abstract This article deals with the case study of a marina located in Roccella Jonica (Italy), where a wave energy harvester belonging to the family of U-Oscillating Water Columns (U-OWC) is going to be installed. U-OWCs are wave energy harvesters composed by a water column exposed to the action of random sea waves and an air pocket connected to the atmosphere by a Power Take - Off (PTO) system. In Roccella Jonica, this device is going to be embedded in a vertical breakwater expanding the main layout of the infrastructure. For ensuring the structural safety of the system, to characterize statistically its response peaks in severe environmental conditions is important. In this context, one of the main difficulties is utilizing appropriate environmental conditions representing real extreme events at the installation site. This article proposes to adopt the DNV trapezoidal storm model for representing the time history of an extreme event in conjunction with a nonlinear U-OWC model. Relevant Monte Carlo simulations show that the DNV storm model provides peak distributions that are rather close to the ones obtained by processing real storm time histories. Thus, it can be adopted for checking the performance of the system in extreme conditions.

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Wave-to-Wire Model of an Oscillating-Water-Column Wave Energy Converter and Its Application to Mediterranean Energy Hot-Spots

Energies ◽

10.3390/en13215582 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5582

Author(s):

Lorenzo Ciappi ◽

Lapo Cheli ◽

Irene Simonetti ◽

Alessandro Bianchini ◽

Giampaolo Manfrida ◽

...

Keyword(s):

Water Column ◽

Energy Production ◽

Analytical Models ◽

Oscillating Water Column ◽

Sea Waves ◽

Energy Potential ◽

Impulse Turbine ◽

Electric Generator ◽

Air Turbine ◽

Secondary Air

Oscillating water column (OWC) systems are among the most credited solutions for an effective conversion of the notable energy potential conveyed by sea waves. Despite a renewed interest, however, they are often still at a demonstration phase and additional research is required to reach industrial maturity. Within this framework, this study provides a wave-to-wire model for OWC systems based on an impulse air turbine. The model performs a comprehensive simulation of the system to estimate the attendant electric energy production for a specific sea state, based on analytical models of the primary (fixed chamber) and secondary (air turbine) converters coupled with the tertiary converter (electric generator). A rigid piston model is proposed to solve the hydrodynamics, thermodynamics, and hydrodynamics of the chamber, in a coupled fashion with the impulse turbine aerodynamics. This is solved with a novel method by considering the cascades as sets of blades, each one consisting of a finite number of airfoils stacked in the radial direction. The model was applied for two Mediterranean sites located in Tuscany and Sardinia (Italy), which were selected to define the optimal geometry of the turbine for a specified chamber. For each system, the developed analytical wave-to-wire model was applied to calculate the performance parameters and the annual energy production in environmental conditions typical of the Mediterranean Sea. The selected impulse turbines are able to convert 13.69 and 39.36 MWh/year, with an efficiency of 4.95% and 4.76%, respectively, thus proving the interesting prospects of the technology.

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The influence of three-dimensional effects on the performance of U-type oscillating water column wave energy harvesters

Renewable Energy ◽

10.1016/j.renene.2017.04.038 ◽

2017 ◽

Vol 111 ◽

pp. 506-522 ◽

Cited By ~ 16

Author(s):

G. Malara ◽

R.P.F. Gomes ◽

F. Arena ◽

J.C.C. Henriques ◽

L.M.C. Gato ◽

...

Keyword(s):

Water Column ◽

Wave Energy ◽

Three Dimensional ◽

Oscillating Water Column ◽

Energy Harvesters ◽

Dimensional Effects

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A wave energy system based on peristaltic pumping of air by sea waves

Scientific Bulletin of Naval Academy ◽

10.21279/1454-864x-19-i1-040 ◽

2019 ◽

Vol XXII (1) ◽

pp. 269-277

Author(s):

Ünsalan D.

Keyword(s):

Water Column ◽

Wave Energy ◽

Air Flow ◽

Energy System ◽

Leeward Side ◽

Channel Height ◽

Oscillating Water Column ◽

Sea Waves ◽

Peristaltic Pumping ◽

Calm Water

Oscillating water column type of wave energy converters have attracted researchers and engineers working on the field of renewable energy systems, despite the problems caused by the alternating direction of air flow through the turbines. This problem has been circumvented by the use of single direction of rotation turbines such as Wells, Denniss-Auld and omnidirectional impulse turbines, albeit with rather low efficiencies. The authors have considered the usage of near-sinusoidal (cnoidal) form of sea waves as the drivers for the linear peristaltic pumping of air along a channel. The conceived device is an inverted U-shaped channel on a barge, aligned in the direction of wave and serves as a channel for the progress of waveform. Air is driven through the channel by peristaltic action to achieve a unidirectional air flow at the leeward end of the channel. An end-wall operated by a float experiencing heaving and surging motions at the leeward side of the channel prevents the escape of pumped air, which instead is directed to an upward duct leading to a turbine. Since the air flow is unidirectional, the use of more convenient air turbines compared to the ones used in oscillating water column devices are enabled. Air flow parameters with wave amplitudes exceeding and less than channel height above the calm water line are analysed using the Airy wave to demonstrate the feasibility of the proposed system analytically. It was found that the optimum solution was achieved when the channel top is at the calm water level

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Performance Analysis of Wind Power Generation Models Using Oscillating Water Column

JRST (Jurnal Riset dan Sain Teknologi) ◽

10.30595/jrst.v4i2.6020 ◽

2020 ◽

Vol 4 (2) ◽

pp. 57

Author(s):

Susastro Susastro ◽

Ardi Noerpamoengkas ◽

Miftahul Ulum ◽

Gatot Setyono

Keyword(s):

Electric Power ◽

Water Column ◽

Renewable Resources ◽

Water Wave ◽

Electrical Energy ◽

Maximum Load ◽

Maximum Efficiency ◽

Oscillating Water Column ◽

Sea Waves ◽

Global Era

In this global era there are many resources that can be used one of them is, renewable resources such as sea waves. waves can be used as a generated of electrical energy. electrical energy that utilizes the occurrence of sea waves now can be applied in developed and developing countries. One method of conversion that can be done to convert wave energy into electrical energy is by using an oscillating water column. In this research, the turbine of oscillating water column was made using turbine wells with variations in rotation at 40, 50 and 58.3 rpm. the results it’s power of turbine, power of generator and efficiency system. The method used is the experimental method by testing the prototype using a low water wave on a laboratory scale. The results obtained from the experiment are that the electric power at the maximum load generated by the generator is 0.002875 Watt at a rotation of 50 rpm. While the lowest electric power at maximum load is 0.0004 W with a rotation of 40 rpm. The maximum efficiency of the system at load is 4.691% which occurs at a rotation of 50 rpm

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