Experimental and Numerical Analysis of Performance of Oscillating Water Column Wave Energy Converter Applicable to Breakwaters

Park, Sewan; Kim, Kyong‐Hwan; Nam, Bo Woo; Kim, Jeong‐Seok; Hong, Keyyong

doi:10.1115/omae2019-96500

Cited by 10 publications

(14 citation statements)

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“…The device was tested at a scale of 1:4 relative to a proposed full-scale deployment as part of a breakwater in a water depth of 12.8 m. The experimental measurements were carried out at the Korea Research Institute of Ships and Ocean Engineering (KRISO) ocean basin in 2019. Preliminary results along with a comparison to CFD calculations were presented in Reference [17]. The geometry and dimensions of the basin are shown in Figure 1, and the wave probe locations are indicated in Figure 2.…”

Section: Experimental Measurementsmentioning

confidence: 99%

“…2-DOF state-space model: Following a similar procedure as for the 1-DOF models, two 2-DOF models were produced. The first 2-DOF model assumes the air flow across the orifice to be incompressible and uses Equation (17) to model the mass flow rate of air between the OWC chamber and atmosphere, while the second model assumes the air flow across the orifice to be compressible, but uses Equation (18) in place of Equation (17). Both 2-DOF models represent the motion of the water column in the KRISO using a modified version of Equation ( 11) for both mode 7 and mode 8, Equation ( 16) to model the pressure variation within the chamber, and either Equation (17) or Equation (18) to model the mass flow rate through the orifice, as appropriate.…”

Section: The National Renewable Energy Laboratory Teammentioning

confidence: 99%

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Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column

Bingham

Nielsen

et al. 2021

Energies

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This paper reports on an ongoing international effort to establish guidelines for numerical modeling of wave energy converters, initiated by the International Energy Agency Technology Collaboration Program for Ocean Energy Systems. Initial results for point absorbers were presented in previous work, and here we present results for a breakwater-mounted Oscillating Water Column (OWC) device. The experimental model is at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1–2% of the internal chamber surface area. Measurements of chamber surface elevation, air flow through the orifice, and pressure difference across the orifice are compared with numerical calculations using both weakly-nonlinear potential flow theory and computational fluid dynamics. Both compressible- and incompressible-flow models are considered, and the effects of air compressibility are found to have a significant influence on the motion of the internal chamber surface. Recommendations are made for reducing uncertainties in future experimental campaigns, which are critical to enable firm conclusions to be drawn about the relative accuracy of the numerical models. It is well-known that boundary element method solutions of the linear potential flow problem (e.g., WAMIT) are singular at infinite frequency when panels are placed directly on the free surface. This is problematic for time-domain solutions where the value of the added mass matrix at infinite frequency is critical, especially for OWC chambers, which are modeled by zero-mass elements on the free surface. A straightforward rational procedure is described to replace ad-hoc solutions to this problem that have been proposed in the literature.

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Section: Experimental Measurementsmentioning

confidence: 99%

Section: The National Renewable Energy Laboratory Teammentioning

confidence: 99%

Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column

Bingham

Nielsen

et al. 2021

Energies

Self Cite

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“…According to their separate findings, results from their practical evaluation affirms an improved economic viability of the OWC wave energy converter. This has enhanced an improvement in the applicability of the sloppy breakwater section thus reducing cost in construction of chamber structure [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Analysis of Oscillating Water Column Using CFD Code

Tj¹

2021

PSBJ

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Oscillating water Column (OWC) methods for power extraction from the oceans and sea waves have been actively investigated for quite a number of years but there is still much work to do in this promising area of wet renewable energy source. In the past, most of the OWC installations have been shore based, thus; a move toward the use of near and off-shore buoys is taken into consideration. Thereby the extension of the predictive capabilities to cover these installations is highly desirable.Hence, the use of commercial Computational Fluid Dynamics (CFD) codes for this type of application is relatively novel and offers great modelling promises. Therefore, the paper presentation of hydrodynamic analysis of OWC using CFD code is a way forward in analyzing the effectiveness of OWC for power generation. The CFD simulation code has the proficiency in the prediction of hydrodynamics analysis results in the OWC device. Thus, it is used to generate pneumatic pressure results, air flow velocities and volume fraction results at different vent diameters. A summarized result confirms 0.8m vent diameter opening of OWC construction for effective power production. Also, a wave height ratio of 0.238 with 1.7m water depth yields a maximum hydrodynamic efficiency of 45.57%. This is an indication that water depth is one of the controlling factors for the production of high magnitude of wave which is an influencing characteristics of the turbine efficiency of the OWC device.Therefore, the consideration of offshore OWC at a reasonable water depth in the nearby seas and oceans will generate effective power supply to support a nation's power grid for proficient consumers.

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“…The sloped OWC has an energy extraction performance similar to that of the vertical OWC device, and its installation on the slope of the bottom-mounted breakwater, the existing onshore structure, is advantageous. As a recent study on the sloped OWC chamber, Park, et al (2018b) measured the relative wave elevation inside the chamber, according to the change in skirt and width of a sloped OWC chamber, via a 2D wave tank experiment. In addition, by performing computational fluid dynamics (CFD) analysis, the wave elevation was calculated in two OWC chamber conditions: one with the chamber open, where the chamber pneumatic pressure is equal to the atmospheric pressure, and the other where the duct is installed above the chamber, such that chamber pneumatic pressure exists.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Wave Energy Extraction Performance According to the Body Shape and Scale of the Breakwater-integrated Sloped OWC

Yang

Min

Koo

2021

J. Ocean Eng. Technol.

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Research on the development of marine renewable energy is actively in progress. Various studies are being conducted on the development of wave energy converters. In this study, a numerical analysis of wave-energy extraction performance was performed according to the body shape and scale of the sloped oscillating water column (OWC) wave energy converter (WEC), which can be connected with the breakwater. The sloped OWC WEC was modeled in the time domain using a two-dimensional fully nonlinear numerical wave tank. The nonlinear free surface condition in the chamber was derived to represent the pneumatic pressure owing to the wave column motion and viscous energy loss at the chamber entrance. The free surface elevations in the sloped chamber were calculated at various incident wave periods. For verification, the results were compared with the 1:20 scaled model test. The maximum wave energy extraction was estimated with a pneumatic damping coefficient. To calculate the energy extraction of the actual size WEC, OWC models approximately 20 times larger than the scale model were calculated, and the viscous damping coefficient according to each size was predicted and applied. It was verified that the energy, owing to the airflow in the chamber, increased as the incident wave period increased, and the maximum efficiency of energy extraction was approximately 40% of the incident wave energy. Under the given incident wave conditions, the maximum extractable wave power at a chamber length of 5 m and a skirt draft of 2 m was approximately 4.59 kW/m.

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Experimental and Numerical Analysis of Performance of Oscillating Water Column Wave Energy Converter Applicable to Breakwaters

Cited by 10 publications

References 0 publications

Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column

Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column

Hydrodynamic Analysis of Oscillating Water Column Using CFD Code

Numerical Analysis of Wave Energy Extraction Performance According to the Body Shape and Scale of the Breakwater-integrated Sloped OWC

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