Jiyuan Jin

Numerical Prediction for Overtopping Performance of OWEC

Overtopping wave energy converter is an offshore wave energy converter for collecting the overtopping waves converting the water pressure head into electric power through the hydro turbines. This paper presents a numerical wave tank based on the commercial CFD code Fluent. The Reynolds averaged Naiver-Stokes and VOF model is utilized to generate the 2D numerical linear propagating waves, which has been validated by the analytical solutions. Several incident wave conditions and shape parameters are calculated in the optimal designing investigation of the overtopping characteristics and discharge for the overtopping wave energy converter.

Review of Application of VOF-Based NWT on Integrated OWC System

Abstract - Oscillating water column is the most widely used ocean energy converting systems all over theworld. The operating performance is influenced by the efficiencies of the two converting stages in the OWCchamber-turbine integrated system. In order to consider the effects of the turbine, the orifice model are carriedout. The VOF based Numerical Wave Tank (NWT) is utilized to simulate the water column oscillation insidethe chamber and the results are compared with corresponding experimental data. This paper reviews the stateof the art in interaction among wave elevation inside the chamber and air flow rate in the duct, which are con-sidered the turbine effects. Effects of incident wave conditions and several shape parameters on the operatingperformance of OWC chamber are investigated numerically. The effects of the impulse turbine on the integratedsystem and interaction among the wave elevation, pressure and air flow velocities variations are investigated.Keywords: Integrated System(통합시스템), Numerical Wave Tank(수치조파수조), Orifice(오리피스),Oscillating Water Column(진동수주 ), Wave Energy Conversion(파력에너지변환 )

Performance of Oscillating Water Column type Wave Energy Converter in Oblique Waves

진동수주형 파력발전시스템의 성능은 OWC챔버의 형상 뿐만 아니라 입사파의 각도와 터빈의 효과로 인한 압력강하등과 같은 작동환경의 영향도 받는다. 기존의 대부분 연구들은 파랑에너지 흡수효율에 초점을 맞췄기 때문에 입사파 방향이 OWC챔버 입구면과 직각을 이룬다는 가정 하에 수행되었다. 하지만 실해역에서는 입사파가 해양환경에 따라 사파의 형태로 입사하게 될 것이고, 고정식 구조물인 경우에는 그 영향이 더욱 지배적이다. 본 논문은 실험 및 수치해석적인 방법으로 사파중 OWC챔버의 성능에 대하여 고찰하였다. 실험은 3차원 조파수조를 이용하여 다양한 입사파 각도조건에서 수행하였다. 터빈의 영향을 고려하기 위하여 오리피스를 적용하여 챔버내 진동수주의 수위변동을 계측하였다. VOF모델을 기반으로 한 수치조파수조를 구축하여 실험과 동일한 조건으로 계산을 수행하여 실험결과와 비교분석하여 공기실과 그 인근의 유동변화를 고찰하였다.

A wave focusing device for OWC wave energy convertor

Oscillating Water Column (OWC) device has been widely employed in the wave energy conversion. Wave Focusing Device (WFD) is proposed to improve the operating performance of OWC chamber. In the present paper, a 3D Numerical Wave Tank (NWT) using two-phase VOF model is utilized to simulate the generation and propagation of incident regular waves. 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 the regular waves. The effects of WFD on the operating performance of OWC chamber are investigated numerically.