Tidal Current Power System Research Articles

Application of an Airfoil to the Tidal Turbine Design by Analyzing Two-dimensional Performance in the Water

The tidal turbine, the first device converting the in-line flow energy into rotational motion, is one of the crucial components that affects the performance of the tidal current power system. The tidal turbine is designed by using BEMT (Blade Element Momentum Theory) developed for wind turbine that has large similarities. But the differences exist in range of Reynolds number and in working fluid that should be considered for tidal turbine design. Since the airfoil profile has been developed for wind turbine, it might contain essential errors in 2-dimensional characteristics. In this study, using validated CFD (Computational Fluid Dynamics) analysis method with experimental data obtained from flume tank, the 2-dimensional airfoil performance was evaluated considering operating conditions of the tidal turbine for design optimization. Based on the obtained characteristics of the airfoil, the horizontal axis tidal turbine of 10m diameter was designed. Performance of the designed turbine has been analyzed, and the results are summarized in this paper.

Shape Design of the Duct for Tidal Converters Using Both Numerical and Experimental Approaches (pre-2015)

Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Among the various ocean energy sources, tidal current power (TCP) is recognized as the most promising energy source in terms of predictability and reliability. The enormous energy potential in TCP fields has been exploited by installing TCP systems. The flow velocity is the most important factor for power estimation of a tidal current power system. The kinetic energy of the flow is proportional to the cube of the flow’s velocity, and velocity is a critical variable in the performance of the system. Since the duct can accelerate the flow velocity, its use could expand the applicable areas of tidal devices to relatively low velocity sites. The inclined angle of the duct and the shapes of inlet and outlet affect the acceleration rates of the flow inside the duct. In addition, the volume of the duct can affect the flow velocity amplification performance. To investigate the effects of parameters that increase the flow velocity, a series of simulations are performed using the commercial computational fluid dynamics (CFD) code ANSYS-CFX. Experimental investigations were conducted using a circulation water channel (CWC).

Development of Tidal Current Power System

Development of Tidal Current Power System

On the natural frequency of tidal current power systems—A discussion of sea testing

To study the wet natural frequency (in water) and dry natural frequency (in air) of a tidal current turbine, we conducted a two-year measurement campaign by deploying a full-scale prototype of the system. In this article, a theoretical model is developed and validated with the frequency measurements. It reveals the measured wet natural frequency of the system could approach half that of the dry one. The measurements also show that inflow turbulence is very important in the excitation of system resonances that can lead to system failure. We also briefly discuss how the wet frequency varies over a long period.

사보니우스형 조류발전 터빈의 설계 및 회류수조 실험을 통한 성능평가

Due to global warming, the need to secure alternative resources has become more important nationally. Because of the very strong current on the west coast, with a tidal range of up to 10 m, there are many suitable sites for the application of TCP (tidal current power) in Korea. In the southwest region, a strong current is created in the narrow channels between the numerous islands. A rotor is an essential component that can convert tidal current energy into rotational energy to generate electricity. The design optimization of a rotor is very important to maximize the power production. The performance of a rotor can be determined using various parameters, including the number of blades, shape, sectional size, diameter, etc. There are many offshore jetties and piers with high current velocities. Thus, a VAT (vertical axis turbine) system, which can generate power regardless of flow direction changes, could be effectively applied to cylindrical structures. A VAT system could give an advantage to a caisson-type breakwater because it allows water to circulate well. This paper introduces a multi-layer vertical axis tidal current power system. A Savonius turbine was designed, and a performance analysis was carried out using CFD. A physical model was also demonstrated in CWC, and the results are compared with CFD.

Wake Effect on HAT Tidal Current Power Device Performance

The rotor that initially converts the flow energy into rotational energy is a very important component that affects the efficiency of the entire tidal current power system. Rotor performance is determined by various design variables. Power generation is strongly dependent on the incoming flow velocity and the size of the rotor. To extract a large quantity of power, a tidal current farm is necessary with a multi-arrangement of devices in the ocean. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance, considering the interaction problems, needs to be investigated to maximize the power generation in a limited available area. The downstream rotor efficiency is affected by the wake produced from the upstream rotor. This paper introduces the performance of a downstream rotor affected by wakes from an upstream rotor, demonstrating the interference affecting various gabs between devices.

복합배치 수평축 조류발전 로터의 간섭성능 고찰

Tidal current power system is the energy converter which converts the kinetic energy of tidal stream into electric energy. The performance of the rotor which initially converts the energy is determined by various design factors and it should be optimized by the ocean environment of the field. Flow direction changes due to rise and fall of the tides, but horizontal axis turbine is very sensitive to direction of flow. To investigate the rotor performance considering the interaction problems with incidence angle of flow, series of experiments have been conducted. The results and findings are summarized in the paper.