케이슨 내장형 파력발전 구조물의 형상에 관한 기초적 연구

Abstract

Preliminary Study for Optimum Shape of Caisson Structure Embedding Wave Power Generation

Jong-Soo Lee

Department of Ocean engineering, Graduate School Pukyong National University

ABSTRACT

In this study, the maximum water particle velocity, in the internal water duct of caisson structure embedding wave power generation, was investigated by hydraulic experiments and numerical modelling for optimum structure's shape. It was considered that water oscillating turbine could be installed within the internal water duct in caisson structure. In this case, the water velocity in the duct is the main parameter of the turbine's power converting efficiency, therefore the maximum water velocity characteristics was investigated in various wave height and period on various structure shape parameter, e.g. specification and location of OWC(Oscillating Water Column) in the water duct, the angle and length of front slope for wave energy convergence and so on. Before the main study, worldwide wave power generation structures and wave resource was investigated and domestic wave resource study was reviewed, suitable site for realities installation was selected and wave data analyzed subsequently. The selected field was evaluated as favorable site in Korea by wave data analysis, which were adopted as wave conditions for hydraulic experiments and numerical modeling. For further study of optimum structure, main design parameters were investigated through structure concept design and optimum design algorithm was suggested for maximizing power converting efficiency. In hydraulic experiments, the characteristics of maximum water velocities was investigated against numerical modelling results from FLOW-3D based on VOF and FAVOR method. As the results, the maximum water velocities were sensitively increased by high wave height and long wave period. The various structures were investigated for optimum structure shape with changing length and location of OWC, angle and length of front slope by 2D numerical modelling, CADMAS-SURF. The main results are summarized as follows; 1) The maximum water velocity in water duct was increased by OWC and the effect is almost 3 times higher than in case of non-OWC on wave period 9 sec. 2) The distinguishable excellent water velocities were detected in 15 m OWC length through whole wave period domain generally, which placed in higher than the biggest velocity value of any other cases. Especially the velocity peak, considered resonance, was detected around 6 sec wave period. 3) OWC location, the length of water duct, is important parameter related to water velocity in the water duct, e.g. short duct makes high water velocity. It's suitable 5 m OWC length in 7∼8 sec wave period and 15 m OWC length in below 6 sec wave period, however it would be compatible 15 m OWC length for ordinary power generation. 4) Water velocity becomes as important parameter as increased wave height and wave period. As a result, 30〫 front slope is optimum angle for maximum water velocity in the water duct. 5) 8 m front slope is enough to increasing water velocity, which could role as economic design for optimum caisson structure.