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Author

Keyyong Hong

Other affiliations: Ocean University of China
Bio: Keyyong Hong is an academic researcher from Korean Ocean Research and Development Institute. The author has contributed to research in topics: Oscillating Water Column & Magnet. The author has an hindex of 11, co-authored 79 publications receiving 469 citations. Previous affiliations of Keyyong Hong include Ocean University of China.


Papers
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01 Jan 2008
TL;DR: In this paper, a numerical wave tank (NWT) based on FLUENT using two-phase VOF model for incompressible viscous flow is presented for the investigation of wave energy converting performance of the Oscillating Water Column (OWC) chamber.
Abstract: In this paper, a numerical wave tank (NWT) based on FLUENT using two-phase VOF model for incompressible viscous flow is presented for the investigation of wave energy converting performance of the Oscillating Water Column (OWC) chamber. The NWT consists of the continuity equation, the Reynolds-averaged Navier-Stokes’ equation and the two-phase fractional VOF function. The standard e − k turbulence model, finite volume method, NITA-PISO algorithm and dynamic mesh technique are employed to generate the 2D and 3D regular incident waves. The oscillating amplitude of water column in the chamber and bi-directional air flow in the duct installed on the top of the chamber are calculated, and compared with experimental data to verify the validation of the present NWT. The nozzle effects of the chamber-duct system on the relative amplitudes of the inner free water surface and air flow rate in the duct are investigated.

60 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical wave tank based on the two-phase VOF model is established to investigate the operating performance of OWC air chamber and the effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied.
Abstract: Oscillating Water Column (OWC) wave energy converting system is one of the most widely used facilities all over the world. The air chamber is utilized to convert the wave energy into the pneumatic energy. The numerical wave tank based on the two-phase VOF model is established in the present study to investigate the operating performance of OWC air chamber. The RANS equations, standard k-ɛ turbulence model and dynamic mesh technology are employed in the numerical model. The effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied and the capability of the present numerical wave tank on the corresponding engineering application is validated.

45 citations

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TL;DR: In this article, the authors presented electromagnetic modeling and analysis of the detent force in a permanent magnet linear synchronous machine (PMLSM) according to auxiliary teeth configuration and derived analytical solutions for magnetic fields generated by PMs.
Abstract: This paper presents electromagnetic modeling and analysis of the detent force in a permanent magnet linear synchronous machine (PMLSM) according to auxiliary teeth configuration. Analytical solutions for magnetic fields generated by PMs are derived based on the Maxwell equation in terms of a 2-D Cartesian coordinate system. The magnetic vector potential of each subdomain (PM, air-gap, slot, and end region) is derived, and the field solution is obtained by applying the boundary and interface conditions between the subdomains. Based on the analytical solution, the magnetic force is derived by using the Maxwell stress tensor. All the analytical results were extensively validated using nonlinear finite-element analysis and experimental results. Using the proposed method, we investigated the influence of the machine parameters on the detent force. Therefore, the proposed method can be very useful in the initial design and optimization process of PMLSM for detent force analysis.

42 citations

01 Jan 2007
TL;DR: In this paper, the effects of shape parameters of a bottom-mounted OWC chamber in a view of wave energy absorbing capability are analyzed and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution.
Abstract: Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. In numerical scheme, the potential problem inside the chamber is solved by use of the Green integral equation associated with the Rankine Green function, while outer problem with the Kelvin Green function taking account of fluctuating air pressure in the chamber. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly. We applied the approach to OWC chamber design of Chagwi-Do wave energy converter which is planned to be installed in Jeju, one of the most promising wave power generation sites in Korean coastal water.

27 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical wave tank (NWT) using two-phase volume of fluid (VOF) model is utilized to simulate the generation and propagation of incident regular waves, and water column oscillation inside the chamber.
Abstract: Oscillating water column (OWC) device has been widely employed in the wave energy conversion. In the present paper, a numerical wave tank (NWT) using two-phase volume of fluid (VOF) model is utilized to simulate the generation and propagation of incident regular waves, and water column oscillation inside the chamber. The NWT consists of the continuity equation, the Reynolds-averaged Navier-Stokes equations, and the two-phase VOF functions. The standard k-ϵ turbulence model, the finite volume method, NITA-PISO algorithm, and dynamic mesh technique are employed to generate 2 Dimensional (2D) regular waves. The numerical results are compared and validated with corresponding experimental data. Effects of incident wave conditions and several structure parameters on the operating performance of OWC chamber are investigated numerically.

21 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, different approaches to model nonlinear wave-device interaction are presented, highlighting their advantages and drawbacks, as well as new methods such as system-identification models, smoothed particle hydrodynamics or nonlinear potential flow methods.
Abstract: The wave energy sector has made and is still doing a great effort in order to open up a niche in the energy market, working on several and diverse concepts and making advances in all aspects towards more efficient technologies However, economic viability has not been achieved yet, for which maximisation of power production over the full range of sea conditions is crucial Precise mathematical models are essential to accurately reproduce the behaviour, including nonlinear dynamics, and understand the performance of wave energy converters Therefore, nonlinear models must be considered, which are required for power absorption assessment, simulation of devices motion and model-based control systems Main sources of nonlinear dynamics within the entire chain of a wave energy converter - incoming wave trains, wave-structure interaction, power take-off systems or mooring lines- are identified, with especial attention to the wave-device hydrodynamic interaction, and their influence is studied in the present paper for different types of converters In addition, different approaches to model nonlinear wave-device interaction are presented, highlighting their advantages and drawbacks Besides the traditional Navier-Stokes equations or potential flow methods, ‘new’ methods such as system-identification models, smoothed particle hydrodynamics or nonlinear potential flow methods are analysed

170 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical method based on a two-phase level set with the global mass correction and immersed boundary method is developed to simulate wave interaction with a semi-submerged chamber.

158 citations

Journal ArticleDOI
TL;DR: The power take-off systems of the wave energy converters (WEC) based on the different working methods of their power take off systems are reviewed, showing that the mechanical direct drive system is the most popular.

143 citations

Journal ArticleDOI
TL;DR: A thorough review of high-fidelity numerical modelling of WECs using CFD-based NWTs using CNWTs is presented and tries to make a step towards a best practice guideline for the applications of CFD in the field of wave energy.
Abstract: For the research and development (R&D) of wave energy converters (WECs), numerical wave tanks (NWTs) provide an excellent numerical tool, enabling a cost-effective testbed for WEC experimentation, analysis and optimisation. Different methods for simulating the fluid dynamics and fluid structure interaction (FSI) within the NWT have been developed over the years, with increasing levels of fidelity, and associated computational expense. In the past, the high computational requirements largely precluded Computational Fluid Dynamics (CFD) from being applied to WEC analysis. However, the continual improvement and availability of high performance computing has led to the steady increase of CFD-based NWTs (CNWT) for WEC experiments. No attempt has yet been undertaken to comprehensively review CNWT approaches for WECs. This paper fills this gap and presents a thorough review of high-fidelity numerical modelling of WECs using CNWTs. In addition to collating the published literature, this review tries to make a step towards a best practice guideline for the applications of CFD in the field of wave energy.

142 citations