Currently, many nations in the world make a strong effort to exploit the new and renewable energy. Tide and Tidal Current Energy are the constant and regular power sources with higher and more stable quality compared to other renewable sources. The present paper investigate the status of Tide and Tidal Current energy analyzing its latest technology and development.

본 연구에서는 길이가 다른 장방형 실린더 사이에서 발생하는 제트류가 후류에 미치는 영향을 알아보기 위해 회류수조에서 PIV기법을 사용하여 실험을 실시하였다. 장방형 실린더의 높이(h)와 실린더 사이의 간격(gap)은 10mm이며 폭(B)은 300mm로 하였다. 유동방향의 모델의 길이(L)는 30mm, 60mm, 90mm 및 120mm를 각각 적용하였으며, 모델의 높이(H=30mm)를 기준으로 길이의 비가 1, 2, 3,및 4이다. 유입유동은 조류의 수심에 따른 차이를 감안하여 모델의 높이(H)를 기준으로 Re=1.4×104, Re=2.0×104, Re=2.9×104를 각각 적용하였으며. 유동계측을 위한 영역은 실린더 후방으로 모델 높이의 5배까지 설정하였다. 실험결과 유속이 증가함에 따라 와의 크기가 후류영역으로 증가하며, 근접 후류에서는 장방형 구조물일수록 관통류의 속도성분이 증가하는 특성을 나타냈다. 또한 후류로 갈수록 속도결손은 유입유동이 증가할수록 종횡비가 작은 경우에 크게 나타났다.

In this study, we have modeled a subsonic diffuser with rectangular prism and tried to investigate the influence of a turbulent wake flow by numerical simulation using computational fluid dynamics based on steady-state Navier-Stokes equation and standard k-ε model. A commercial CFD program, FLUENT, is used on the analysis. The turbulent wake is generated by a rectangular prism, which is installed at the diffuser. Flow Uniformity Showed the best results in the case of AR=1:1 and tended to be uniform in the critical point at Re=8.8×103

Freezing of the pure water saturating a packed bed of spheres in a rectangular cavity is performed experimentally to investigate the effect of bead diameter on the heat transfer rate and temperature vs. time history for the pure water freezing experiments were compared with the freezing of the binary solution(HO-NaCl). Spherical soda-lime glass beads of 2.85mm and 6mm in average diameter constitute the porous medium. The system is cooled through its bottom surface, and the top is maintained at a temperature above the liquids. There was small effect on the temperature distribution in the system of the porosity difference.

There are vertical wall to prevent of circulation or pollution during building of ocean structures like a dam and bridge in the harbors area and the sea. Inflow fluid and base of structure are important thing as one of the structural design factors for this interception wall like a vertical wall and watertight wall. In this study, it is revealed that at least 2,000 instantaneous velocity field data are required for ensemble average to get reliable turbulence statistics. The flow behind of vertical wall was investigated using the PIV system from this study. From the results, the large vortex flow developed in recirculation zone for one row wall and two vortex flows developed over two rows. Scale of the vortices in recirculation zone was decreased to 45% over three rows.

In this study, we have modeled a wide angle diffuser with rectangular prism and tried to investigate the influence of a turbulent wake flow by PIV and a numerical simulation using computational fluid dynamics based on steady-state Navier-Stokes equation and standard k-ε model. A commercial CFD program, FLUENT, is used on the analysis. The turbulent wake is generated by a rectangular prism, which is installed at the diffuser. The results show that it is possible to flow control by installing a rectangular prism within the diffuser and velocity recovery is the highest in aspect ratio 1:1.

본 연구에서는 수중 삼각형상구조물의 경사도와 레이놀즈 수 변화에 따른 구조물 주위의 유동특성을 분석하였다. 모델링한 삼각형상구조물 주위의 유동장은 회류수조에서 가시화실험과 입자영상유속계(PIV)를 이용하여 계측하였다. 실험결과 경사각이 45°인 삼각형상구조물이 레이놀즈 수 Re=2.9×10³에서 구조물 높이의 2.7배까지 상승하는 속도성분이 나타났다. 레이놀즈 수가 일정할 때 경사각이 클수록 구조물 후방에 하강하는 속도성분이 크게 나타났고, y/hs=1.75이상의 영역에서는 경사각과 레이놀즈 수가 구조물 후방의 유동형태에 변화를 주지 않았다.

For more efficient air-conditioning in large scaled vessels, structure of air inlet room and location of supply fan are very important. In this study, we have modeled an air intake room of large scaled vessels and tried to examine surrounding flow characteristics around supply fan by a numerical simulation using computational fluid dynamics based on three dimensional steady-state Navier-Stokes equation and standard k-ε model. A commercial CFD program, FLUENT, is used on the analysis. Finally, the analysis showed that the supply fan should be located at the inner side rather than outer side of air intake room, which was original design

Since 2003, policies and practices related to the reduction of CO2 gas emission from ships has been discussing by the International Maritime Organization. The representative emission index and indicator are the EEDI (Energy Efficiency Design Index) for the new ships and EEOI (Energy Efficiency Operational Indicator) during the voyage. In this paper a water tank test and procedure development are introduced for the purpose of improving EEDI. The results showed good agreement explaining the characteristics properly.

It is intended to develop an experimental apparatus which can visualize flow patterns in condensate water reuse system with various cross sections. PVC particles on fluid surface help to obtain clear flow images. The flow region that were found in the experiments are steady, unsteady and significantly-mixed flows.

Pneumatic exercise equipment is a device used for physical exercise. The difference to regular weights or exercise equipment is that the weight stacks, wires and other moving parts are replaced with a pneumatic cylinder whose resistance can be adjusted with air pressure. In this study, power pattern of the equipment in the various pneumatics and the effectiveness of the system were investigated.

In this study, numerical simulation has been conducted to investigate flow characteristics in air supply room for container vessels by a 3-dimension numerical simulation. A commercial CFD program, FLUENT, is used on the analysis. It is shown that the air supply efficiency in this room can be improved by changing position of axial fan, even though other conditions still remain unchanged.

In this study, we modeled a actual shape of a plate heat exchanger into triangular grooved channel and tried to examine flow characteristics experimentally by particle image velocimetry. Five Reynolds numbers were selected with the height of grooved channel and sectional mean velocity of inlet flow. As a result, the triangular grooved channel had a compound flow consisting of the flow in lower channel and the groove flow receiving shear stress by the channel flow. The sheared mixing layer, in the boundary between the triangular groove and the channel, affected main flow to raise turbulent in the channel.

In this study, we have modeled a ship or marine structure into a rectangular resistance body and tried to examine surrounding flow characteristics and pressure distributions behind the resistance body experimentally and investigated pressure characteristics by a 3-dimension numerical simulation. As a result, the numerical simulation predictions were shown to compare well with PIV data. and the perpendicular velocity component behind x/H=0 varies in size with the recycle flow shapes formed from the influence of the resistance body, but generally it shows a negative distribution and there is a decreasing pattern as it goes to the down part.