• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.1
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• pp.9-16
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• 2019

Flow velocity changes in the shroud system for tidal current power generation due to experimental flow velocities and blade geometry changes were analyzed by hydraulic experiment and numerical simulation. Through the hydraulic experiment, flow velocities at inlet of shroud system and RPM according to blade geometry were measured, and numerical simulation was used to analyze flow velocity changes in shroud. When the experimental flow velocity was increased by about 28% and the shape of the airfoil was applied, the measured flow velocity at the shroud inlet tended to increase by up to about 56%. On the other hand, when airfoil-shaped blades were installed, the flow velocity at the inlet tended to increase by up to 14% compared to conventional blades, and RPM was also the highest at the same conditions. The hydraulic experiment and numerical simulation results showed an error of about 13%, and the trends of the flow velocity changes in each result are similar. Numerical simulation of the flow velocity changes in the shroud showed that the flow velocity tended to increase 1.7 times at the front of the blade compared to the inlet. The results of the flow velocity change analysis in the shroud system obtained from this study will provide the basic data necessary for the development of efficient shroud system for tidal current power generation.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.409-418
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• 1999

Gamcheon Bay has complicated and unique flow pattern which is affected by topography characteristics of a semi-closed bay and warm water discharge from the power plant located at the bay. It is very important to consider warm water discharge with tidal period and wind effects, which are mainly acting on the surface flow patterns in Gamcheon Bay. The results of observation show as follows; i) Because Gamcheon bay has much elongated shape to the north-south direction and narrow entrance with two separated breakwaters, the flow is very weak inside the bay. ii) The main flow path is at the west side of the bay. The direction of flood current is northward along the west side of the bay and the direction of ebb current is southward along the west side of the bay. The southward direction of warm water discharge has curved to the west side of the bay. iii)At the period of flood current for neap tide, the flow direction is southward in the bay, which is thought by the effects of warm water discharge. But at the bottom layer, the effects of tidal current reached to the middle of the bay, and showed features like eddy. iv) The wind effect is very strong, especially, prominent in the west and east side of the bay.

• Journal of Korean Port Research
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• v.11 no.2
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• pp.241-255
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• 1997

Three dimensional numerical model is used to simulate the circulation patterns in the Gamcheon Bay located in Pusan, Korea and compared with the observed data. The model is forced by winds, tidal elevation at open boundaries, and warm water discharged from the outfall of power plant, Turbulence mixing coefficients are calculated according to a ${\kippa}-{\varepsilon}$ turbulence closure submodel. Temperature, salinty and current are measuted extensively and these measuted data are compared with the simulation results. Eddy-like features exist both in observed data dna simulation results. These eddies are the results of interaction with the weak tidal current, wind driven current and warm water discharges. Compensational deeects are also found to exit such that while surface current is strong, bottom current tends to weaken and vice versa.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.620-623
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• 2009

여러 해양에너지 중 유체의 빠른 흐름을 이용하는 조류발전은 서해안과 남해안에 적용하기에 적합하며 해양환경의 영향을 최소화 하면서 많은 에너지를 연속적으로 생산할 수 있는 장점이 있다. 조류발전에서 1차적으로 에너지를 변환시키는 로터는 조류발전시스템의 주요한 장치중의 하나로 여러 변수에 의해 그 성능이 결정된다. 블래이드 수, 형상, 단면적, 허브, 직경 등 여러 요소를 고려하여 로터를 설계하며, 설계정보와 실험데이터를 바탕으로 수치모델을 구현하여 실험에서 직접 계측할 수 없는 로터 주변의 유체현상 및 간섭영향 등을 예측할 수 있다. 본 논문에서는 변화하는 유속에 따른 HAT 로터의 시동속도, 회전수를 측정하여 로터 형상과 허브-직경비가 다른 로터의 성능을 고찰하고, 이를 수치모델로 구현하여 로터주변 유동변화를 연구하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.163.1-163.1
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• 2011

세계는 지금 지구 온난화 및 화석연료의 고갈로 인해 대체 에너지 자원의 확보문제가 급속히 대두되고 있다. 이에 조류발전은 오염이 발생하지 않는 친환경 에너지원으로서, 날씨나 계절에 상관없이 항상 발전할 수 있는 신뢰성 있는 에너지이며, 높은 밀도를 가지는 작동유체가 수차에 미치는 영향 또한 크므로 지속적으로 예측이 가능한 장점을 가지고 있다. 이러한 조류에너지는 실 해역에 적용하기 위해서는 전격유효 전력이 생산 가능한 지리적 요인에 대한 고찰과 더불어 조류발전 터빈의 개념설계가 고려되어야 한다. 본 연구는 다양한 설치 공간을 형성할 수 있으며, 장, 단점이 보완될 수 있는 조류발전 터빈의 개념설계 연구 단계로서, 내부 유동 특성을 고려하여 입구를 설계하였으며, 일정한 속도로 유입되는 유량을 노즐의 장착을 통해 에너지 밀도를 높일 수 있게 된다. 이러한 개념형상 설계로 추가 작동이나, 장치의 사용 없이 양방향 발전이 가능해 진다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.241-255
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• 2012

Three types of 100 kW-class tidal stream turbines are proposed and their performance is studied both numerically and experimentally. Following a wind turbine design procedure, a base blade is derived and two additional blades are newly designed focusing more on efficiency and cavitation. For the three designed turbines, a CFD is performed by using FLUENT. The calculations predict that the newly designed turbines perform better than the base turbine and the tip vortex can be reduced with additional efficiency increase by adopting a tip rake. The performance of the turbines is tested in a towing tank with 700 mm models. The scale problem is carefully investigated and the measurements are compared with the CFD results. All the prediction from the CFD is supported by the model experiment with some quantitative discrepancy. The maximum efficiencies are 0.49 (CFD) and 0.45 (experiment) at TSR 5.17 for the turbine with a tip rake.

• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.261-267
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• 2014

Because a change in the natural frequencies of a structure indicates structural health problems, monitoring the natural frequencies crucial. Long-term measurement for the Uldolmok tidal current power plant structure has shown that its natural frequencies fluctuate with a constant cycle twice a day. In this study, lab-scale tests to investigate the causes of these natural frequency fluctuations were carried out in a circulating water channel. Three independent variables in the tests that could affect the fluctuation of the natural frequencies were the water level, current velocity, and boundary condition between the specimen and the bottom of the circulating water channel. The experimental results were verified with numerical ones using ABAQUS. It was found that the fluctuation of the natural frequencies was governed by a decrease in stiffness due to the boundary condition much more than the effect of added mass. In addition, it was found that the natural frequency would decrease with an increase in the tidal current velocity because of its nonlinearity when the boundary condition was severely deteriorated due to damage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.814-815
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.812-813
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.810-811
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• 2009