• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.413-421
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• 2012

This paper proposes the design and implementation of fluid flow generation system by using polypropylene(PP) water capture, which harvests electric energy from the kinetic energy of tidal current or water flow and drives the desired load, and applies it to the discharge drain of Hadong thermal power plant. This experimental system is composed of water captures, driving wheel, gear trains, 10[kW] synchronous generator, and three phase rectifying circuit which drives lamp load for test. The proposed water capturing system which is composed of water captures, rope and driving wheel, rotates as caterpillar according to water flow. This system is very easy to manufacture and more economical than another type of tidal current turbines such as conventional propeller and helical type. Also, we estimated the available fluid flow energy that can be extracted from the cooling water in discharge drain based on drain's cross-sectional area. Therefore, this paper confirms the validity of proposed fluid flow generation system with water captures and the possibility of its application for renewable energy generation in discharge drain of thermal power plant, from the obtained performance characteristic of this energy conversion system.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.154-164
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• 2019

A rotor dynamic analysis is mandatory for stability and design optimization of submerged propellers and turbines. An accurate simulation requires a proper consideration of fluid-induced reaction forces. This paper presents a bi-directional coupling of a bond graph method solver and an unsteady vortex lattice method solver where the former is used to model the rotor dynamics of the power train and the latter is used to predict transient hydrodynamic forces. Due to solver coupling, determination of hydrodynamic coefficients is obsolete and added mass effects are considered automatically. Additionally, power grid and structural faults like grid fluctuations, eccentricity or failure could be investigated using the same model. In this research work a fast, time resolved dynamic simulation of the complete power train is conducted. As an example, the rotor dynamics of a tidal stream turbine is investigated under two inflow conditions: I - shear flow, II - shear flow + water waves.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.235.1-235.1
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• 2010

Two ocean current power parks are suggested in the front and back of the Garyuk draining sluices of Saemankeum in Korea. They are characterized by installing a plurality of ocean current turbine generators which are arranged in five rows respectively in the land-side ocean current power park behind the Garyuk draining sluices and in the sea-side ocean current power park before the Garyuk draining sluices, generating electricity using the ocean current flowing through the Garyuk draining sluices in the ebbs and tides of Yellow sea. The potential energy of tidal difference of 2.611m at neap in Saemankeum can be converted into the kinetic energy of high speed ocean current via the Garyuk draining sluices which makes it possible to run the ocean current power parks on a large scale. The total facility capacity of two ocean current power parks that consist of 240 ocean current turbine generators with 4m diameter of turbine blades is about 134MW, and the expected total annual power output is about 586GWh.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.5
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• pp.247-259
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• 2017

Numerical model with LPT (Lagrangian Particle Tracking) module was used to understand the variation of residence time in the outer sea of the Sihwa lake result operating from the Sihwa tidal power plant. Numerical model was composed in order to investigate the spatial distribution characteristics, the average residence time in each area was calculated by dividing the outer sea area of Sihwa lake into 4 areas. The average residence time of the areas appeared to be increase as it entered the areas located in the inner bay (13 days) from the area located in most outer sea (3 days) both before and during operation. Variation of average residence time by areas were increased in the area that was located in the most outer sea of during operation compared to before operation, and decreased in the other area. Artificial discharges from tidal power plant induces particle traps in the formation of vortex in the area located in the most outer seas, entrainment in the remaining areas, which affects variation in residence time. In other words, the jet flow generated during drainage and the change in the residence time due to the vortex and entrainment action indicate the increase horizontal mixing of water in the outer sea and in the inner bay.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.60-66
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• 2014

Most tidal current turbine designs are focused on medium and large scale for deep sea, less attention is paid in low water level channel, such as the region around the islands and costal sea. This study is to develop a horizontal axis tidal current turbine rotor blade which is applicable to low water level island region in southwest coastal region of Korea. In this study, the hydrofoil NACA63-415 and NACA63-817 are both adopted to analyze. The blade using NACA63-817 showed the higher maximum power coefficient and good performance at small TSR (Tip Speed Ratio), which gives the blade more advantages in operating at lower water level channel, where is characterized by the fast-flowing water. The cavitation pattern of hydrofoil is predicted by the CFD analysis and verified that the NACA63-817 is the appropriate hydrofoil in the test site of tidal current resource and the hydrofoil showed considerable performance in avoiding cavitation.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.617-620
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• 2007

The performance evaluation of the Samcheonpo small-hydropower plant constructed on the October 25th,2006, was carried out focused on the turbine and generator efficiency analysis by using the measurement data. The unreasonable and unrealistic efficiency results are occurred in some periods because of the data variability, uncertainty, and measurement errors and mistakes. Whereas, the big mismatch is the tidal elevation predicted in the design processes. The difference between the measured and estimated tidal elevation is obvious during the low water period. It should be considered and checked in depth on the efficiency analysis of the planned and constructing small-hydro power plants in other coastal areas.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.73-78
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• 2013

CFD (computational fluid dynamics) analyses that considered the dynamic interaction effects between the flow and a turbine were performed to evaluate the power output characteristics of two representative vertical-axis tidal-current turbines: an H-type Darrieus turbine and Gorlov helical turbine (GHT). For this purpose, a commercial CFD code, Star-CCM+, was utilized, and the power output characteristic were investigated in relation to the scale ratio using the relation between the Reynolds number and the lift-to-drag ratio. It was found that the power coefficients were significantly reduced when the scaled model turbine was used, especially when the Reynolds number was lower than $10^5$. The power output characteristics of GHT in relation to the twisting angle were also investigated using a three-dimensional CFD analysis, and it was found that the power coefficient was maximized for the case of a Darrieus turbine, i.e., a twisting angle of $0^{\circ}$, and the torque pulsation ratio was minimized when the blade covered $360^{\circ}$ for the case of a turbine with a twisting angle of $120^{\circ}$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.5
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• pp.586-592
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• 2014

This study looks at the design of a 100 kW blade geometry for a horizontal marine current turbine using the Blade Element Momentum Theory (BEMT) and by using (CFD), the power output, performance and characteristics of the the fluid flow over the blade is estimated. Three basic airfoils; FFA-W3-301, DU-93-W210 and NACA-63418, are used along the blade span and The distribution of the chord length and twist angles along the blade are obtained from the hydrodynamic optimization procedure. The power coefficient curve shows maximum peak at the rated tip speed ratio of 5.17, and the maximum power reaches about 101.82 kW at the power coefficient of 0.495.

• Hwankyungkyoyuk
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• v.23 no.2
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• pp.82-96
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• 2010

The purposes of this study are to investigate the perception of renewable energy technology among elementary school teachers, and confirm whether elementary school teachers have basic knowledge about renewable energy sources, including solar, wind, and tidal power generation. We conducted preliminary interviews to gather information related to other studies about renewable energy. We developed the last interview question about the perception and knowledge of elementary school teachers regarding renewable energy. This study analyzed the transcribed responses of 10 elementary school teachers in Siheung-city, Gyeonggi-do, following 30-minute interviews. The study's findings are as follows. First, elementary school teachers recognize that they are unfamiliar with concepts and they have only shallow content knowledge about renewable energy. And they tended to distorted to other concepts, and analyze to different meanings. Second, elementary school teachers thought that knowledge about renewable energy should be part of a well-rounded education. And they felt positively about solar energy and wind power energy generation but they had a negative view towards tidal power generation because it destroys tideland. Third, teachers tended to confuse solar heat energy and geothermal energy, they tend to think this two energy sources the same. Teachers had generally correct concepts about wind power energy generation. In the case of tidal power generation, elementary school teachers answered mechanically that it is possible on the western sea, and that 'the difference between the rise and fall of the tide' grows. But they could not talk in depth about 'the difference between the rise and fall of the tide' and the force of waves. This suggests that they are answering by simple memorization and without deep understanding.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.610-616
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• 2012

All the countries in the world is currently facing the full scale of energy-climate era currently, and making strong energy policy that will lead to green growth of the future energy resources by utilizing renewable energy as the basis of entering the advanced country becomes the goal of development that satisfies the demand for energy in 21st century. Recently, ocean energy attracted the attention along with the necessity of developing renewable energy. Ocean energy is the one of most prominent recyclable and clean resources that has not been developed yet. So, it is highly required to develop good tidal current energy conversion system in coastal area. The inflow angle that acts against tidal current turbine, seabed effect and the change of efficiency along the occurrence of cavitation were investigated through the wake flow characteristics in this study. Power coefficient degradation by seabed effect did not appear in the condition of this calculation. Efficiency degradation appeared from above $10^{\circ}$ regarding inflow angle and power coefficient was calculated as lower by 7 % at $45^{\circ}$. Torque and power coefficient increased as inflow velocity rose, but power coefficient degradation appeared from above 3m/s when the cavitation happened. So, it was recognized that the larger inflow angle and occurrence of cavitation become the reason for power degradation through the flow characteristics.