• Journal of Advanced Marine Engineering and Technology
• /
• 제36권5호
• /
• pp.707-715
• /
• 2012

Ocean waves are mighty and powerful. Humans have explored the possibility of harnessing this mighty power for decades now. Estimated as suffice, if only, a fraction of this energy is captured and harnessed, the worry for decrease in fossil fuels diminishes and the current energy consumption of the world can be met. Though different types of methods and devices for extracting energy from this nonstop, free source has been proposed, a handful of them have reached commercialization and others are on the verge. This paper discusses the journey so far in terms of devices that have been developed or prototypes proposed or commercialized. Only a list full of them have been discussed though they exist in numbers.

• 한국해양공학회지
• /
• 제25권1호
• /
• pp.8-13
• /
• 2011

A compact array system of small buoys is used for wave energy extraction. To evaluate the performance of this system, hydrodynamic analysis is carried out in regular waves using the higher order boundary element method. The motion response of each buoy is calculated considering hydrodynamic interactions caused by other buoys. The effect of energy extraction device is modeled as a linear damping load. The efficiencies of energy conversion are compared using the various sizes and arrangements of the array system and the damping coefficients for energy extraction. The increase in size or the packing ratio of the system gives better efficiency. However, the wave condition and the cost for the system should be considered to optimize performance from the perspective of engineering and economics. The proposed nondimensionalized damping coefficient for energy extraction is 0.1~0.5.

• Ocean Systems Engineering
• /
• 제11권1호
• /
• pp.1-16
• /
• 2021

Experimental and numerical investigations were conducted to study the performance of a surface-fixed horizontal porous wave barrier in regular waves. The characteristics of the reflection and transmission coefficients, energy dissipation, and vertical wave force were examined versus different porosities of the barrier. Numerical simulations based on 3D Reynolds Averaged Navier-Stokes equations with standard low-Re k-ε turbulent closure and volume of fluid approach were accomplished and compared with the experimental results conducted in a 2D wave tank. Experimental measurements and numerical simulations were shown to be in satisfactory agreement. The qualitative wave behavior propagating over a horizontal porous barrier such as wave run-up, wave breaking, air entrapment, jet flow, and vortex generation was reproduced by CFD computation. Through the discrete harmonic decomposition of the vertical wave force on a wave barrier, the nonlinear characteristics were revealed quantitatively. It was concluded that the surface-fixed horizontal barrier is more effective in dissipating wave energy in the short wave period region and more energy conversion was observed from the first harmonic to higher harmonics with the increase of porosity. The present numerical approach will provide a predictive tool for an accurate and efficient design of the surface-fixed horizontal porous wave barrier.

• Journal of Advanced Marine Engineering and Technology
• /
• 제15권3호
• /
• pp.31-38
• /
• 1991

Due to the structural complexity and the mutual interference of "water columns", the estimations of absorption power for a large wave energy conversion devices of flosting type in ocean could not achieve the desired results. Thus, in this paper the authors will propose a new methodology based on the three dimensional source ditribution method. We distributed the source to the device and the thin & light plate in "water column", And from the behaviour of this plated, the power and the pressure in water column are calculated. But, yet method should be proved to be valid by experiment.

• 한국항해항만학회지
• /
• 제31권10호
• /
• pp.845-852
• /
• 2007

OWE형 파력발전장치는 해수면의 승강운동을 공기실 내의 공기 흐름으로 전환하고 이를 터빈의 구동력으로 사용하는 발전장치이다. 파랑에너지가, 터빈으로 유입되는 공기에너지로 전환하도록 하는 공기실의 내부 수위의 주기적 변동은 상하대칭이 이루어지지 않고, 공기실 내 공기 유동의 압축과 팽창 과정에서 유량차가 발생하게 된다. 본 논문에서는 이를 이용하여 보다 많은 유량을 임펄스터빈의 압력면으로 유도하여 날개의 압력면과 흡입면의 압력차를 크게 하는 Staggered Blade의 적용에 대해 검토하고 그에 대한 성능 해석을 수행하였다. 터빈의 압력면으로의 공기 흐름을 제어하기 위해 Self-Pitched Blade(가변 피치 날개)를 제안하였고, 이러한 유량차를 토대로 동 조건에서 최대의 발전량과 최고 효율의 터빈을 설계하고자 하는데 그 목적이 있다.

• 한국해양공학회지
• /
• 제36권4호
• /
• pp.280-294
• /
• 2022

This study reviews the recent development and research results of a fixed oscillating water column (OWC) wave energy converter (WEC). The OWC WEC can be divided into fixed and floating types based on the installation location and movement of the structure. In this article, the study on a stationary OWC WEC, which is close to commercialization through the accumulation of long-term research achievements, is divided into five research categories with a focus on primary energy conversion research. These research categories include potential-flow-based numerical analysis, wave tank experiments, computational fluid dynamics analyses toward investigation of fluid viscous effects, U-shaped OWC studies that can amplify water surface displacement in the OWC chamber, and studies on OWC prototypes that have been installed and operated in real sea environments. This review will provide an overview of recent research on the stationary OWC WEC and basic information for further detailed studies on the OWC.

• 한국해양환경ㆍ에너지학회지
• /
• 제13권1호
• /
• pp.12-17
• /
• 2010

OWC 파력발전장치는 에너지 변환장치로 널리 사용되고 있고 공기실의 작동성능을 향상시키기 위하여 파랑집중장치를 고안 하였다. 본 논문에서 사용된 수치조파수조는 two-phase VOF모델을 기반으로 하여 구현되었고 재생된 규칙 입사파는 공기실까지 전달되어 내부의 왕복 유동장을 형성하게 하였다. 수치조파수조는 연속방정식, Reynolds-averaged Navier-Stokes방정식, two-phase VOF 법으로 구성 되였고 standard k- 난류모델, 유한체적법, NITA-PISO 알고리즘 그리고 dynamic mesh기능을 채택하였다. OWC 공기실 파랑집중장치의 성능에 대하여 수치적으로 고찰하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.833-838
• /
• 2003

The problem of elastic wave resonance scattering from elastic targets is studied in this paper. A new resonance formalism to extract the elastic resonance information of the target from scattered elastic waves is introduced. The proposed resonance formalism is an extension of the works developed for acoustic wave scattering problems by the author. The classical resonance scattering theory computes reasonable magnitude information of the resonances in each partial wave, but the phase behaves in somewhat irregular way, therefore, is not clearly explainable. The proposed method is developed to obtain physically meaningful magnitude and phase of the resonances. As an example problem, elastic wave scattering from an infinitely-long elastic cylinder was analyzed by the proposed method and compared to the results by RST. In case of no mode conversion, both methods generate identical magnitude. However, the new method computes exact $\pi$ radian phase shills through resonances and anti-resonances while RST produces physically unexplainable phases. In case of mode conversion, in addition to the phase even magnitudes are different. The phase shifts through resonances and antiresonances obtained by the proposed method are not exactly $\pi$ radians due to energy leak by mode conversion. But, the phases by the proposed method show reasonable and intuitively correct behavior compared to those by RST.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
• /
• pp.630-631
• /
• 2009

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Apart from wind and solar, ocean holds tremendous amount of untapped energy in forms such as geothermal vents, tides and waves. The current study looks at generating power using waves and the focus is on the primary energy conversion (first stage conversion) of incoming waves for two different models. Observation of flow characteristics, pressure and the velocity in the augmentation channel as well as the front guide nozzle are presented in the paper. A numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The augmentation channel consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. The analysis was performed using the commercial CFD code.

• 대한기계학회논문집A
• /
• 제39권1호
• /
• pp.79-87
• /
• 2015

요요 진동시스템을 이용한 파력발전 장치의 모델링 및 성능해석을 수행하였다. 본 연구의 파력발전 시스템은 기계적 요소인 요요진동 시스템, 모션정류 시스템, 동력전달 시스템과 전기적 요소인 발전시스템으로 구성된다. 특히 요요 진동시스템을 적용하여 파랑의 입력을 회전운동으로 변환하였으며 입력되는 파랑의 크기가 공진현상에 의해 증폭되어 높은 에너지 변환효율을 갖도록 구성되었다. 기계적 시스템과 전기적 시스템의 임피던스 연결(Impedance matching)을 통해 기계-전기 통합 해석 모델을 수립하였다. 일정 입력 가속도 0.14g 에서 다양한 파랑 주파수와 시스템 감쇠비에 대한 수치적 성능 해석을 진행하였다. 최대 전기적 출력은 공진주파수에서 부하저항이 최적 부하 조건을 만족할 때 발생하였으며, 이때 최대 전기 출력은 290W, 발전 효율은 48%이다. 해석 결과를 통해 공진 현상을 이용하여 파력발전장치의 출력을 크게 증가시킬 수 있음을 확인하였다.