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A 100-W helical-blade vertical-axis wind turbine was designed, manufactured, and tested in a wind tunnel. A relatively low tip-speed ratio of 1.1 was targeted for usage in an urban environment at a rated wind speed of 9 m/s and a rotational speed of 170 rpm. The basic dimensions were determined through a momentum-based design method according to the IEC 61400-2 protocol. The power output was estimated by a mathematical model that takes into account the aerodynamic performance of the NACA0018 blade shape. The lift and drag of the blade with respect to the angle of attack during rotation were calculated using 2D computational fluid dynamics (CFD) simulation to take into account stall region. The average power output calculated by the model was 108.34 W, which satisfies the target output of 100 W. The manufactured wind turbine was tested in a large closed-circuit wind tunnel, and the power outputs were measured for given wind speeds. At the design condition, the measured power output was 114.7 W, which is 5.9% higher than that of the mathematical model. This result validates the proposed design method and power estimation by the mathematical model.

This paper presents the results of a computational fluid dynamics (CFD) study of a wind farm with two sets of 2 MW class wind turbines. CFD analysis was calculated by using the commercial multi-purpose CFD solver ANSYS CFX. Blade design and modeling were based on blade element momentum theory. retain-->The rotational phase of two wind turbine rotors was synchronized, and the distance between the two wind turbines was changed from three to seven times of the rotor diameter. The tilting angle of the 2 MW class wind turbine was set to 5°. A complete wind farm mesh is generated including the rotor, nacelle and tower. The results showed that there was a power output difference due to the wake effect between two wind turbines. The power output of the downstream wind turbine was changed with respect to the separation distance between wind turbines. The optimal compromise between wind farm construction cost, annual energy production and wind turbine lifetime as a function of separation distance is crucial. These CFD results can be applied to wind farm layout design, site evaluation and power output prediction.

This paper presents aerodynamic power outputs of wind turbine of 6 MW wind farm composedof 3 sets of 2 MW wind turbine according to the separation distance by using CFD. Layout design including offshore wind farm and onshore wind farm is key factor for the initial investment cost, annual energy production and maintenance cost. For each wind turbine rotor, not actuator disc model with momentum source but full 3-dimensional model is used for CFD and it has a great technical meaning. Theresults of this study can be applied to the offshore wind farm layout design effectively. Key words: Offshore wind farm, Layout, Computational fluid dynamics, Separation distance, Aerodynamics power output †교신저자(부산대학교 기계공학부, E-mail:kckim@pusan.ac.kr, Tel: 051-510-2324)1 부산대학교 기계공학부 대학원 / (주)디엔디이2 (주)디엔디이 1. 서 론 화석연료 사용 등으로 인한 CO 2 증가는 지구 온난화를 야기하며 기후변화등 인류 생활에 큰 위협이 되고 있다. 이를 극복하기 위한 신․재생에너지에 대한 연구는 선택이 아닌 필수이다[1]. 여러 신․재생에너지원중 풍력에너지는 석탄화력 및 원자력 발전과 대등한 에너지 비용으로 향후 지속적인 성장이 예상된다. 풍력발전은 바람의 운동에너지를 기계적 회전에너지로 변환하고 이를 다시 전기에너지로 변환하는 일종의 에너지 추출기 또는 변환기이다[2]. 향후 기술적 추세는 수 MW급 대형풍력터빈으로 구성된 대규모 해상풍력발전단지가 주류를 이룰 것으로 예상되며 이는 양호한 해상 풍황 조건, 제한된 육상풍력발전단지 부지 및 민원등 여러 요소가 복합된 결과이다[3]. 해상풍력발전단지의 레이아웃 설계는 초기 투자비, 년간 발전량 및 유지 보수비에 영향을 미치는

Most of developed countries, the consumption of fossil fuels has been serious problems that cause serious environment pollution like acid rain, global warming. Also, we have faced that limitation fossil fuels will be exhausted. Currently, small hydropower attracts attention because of its small, clean, renewable, and abundant energy resources to develop. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Tubular-turbine among small hydraulic power generation can be used at low-head. The purpose of this study is to research turbine's efficiency due to runner vane angle using CFD analysis.

As the alternative energy, renewable energy should have been developing by many techniques, in order to substitute the fossil fuel which will be disappeared in the near future. One of the small hydropower generator, main concept of tubular turbine is based on using the different water pressure levels in pipe lines, energy which was initially wasted by using a reducing valve at the end of the pipeline, is collected by turbine in the hydro power generator. A propeller shaped hydro turbine has been used in order to use this renewable pressure energy in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the guide vane opening angle are examined in detail. First, it ensures the reliance of CFD by that of compared with experiment data. After all, the results of performance characteristics of the CFD and experiment show to confirm the data that power, head and efficiency of less than 4%, 2% and 5% respectively. Moreover influences of pressure, tangential and axial velocity distributions on turbine performance are investigated.

The world is facing a serious energy problem which destroying the environment. In addition, fossil fuel such as oil and coal that caused global warming and the environmental problems due to acid rain had been gradually exhausted. To solve this problem that has crisis of energy, it is necessary time and effort for research and development of renewable energy in the future. As alternative energy, small hydropower generation which has output of less or equal to 100kW is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use reducing of a valve at the end of the pipeline, is collected by turbine in the small hydropower generator. In this study, we investigated the influence of the number of runner vanes on the characteristics of tubular-type hydroturbine.

This study examined the aerodynamic power output change of wind turbines with inter-turbine spacing variation for a 6 MW wind farm composed of three sets of 2 MW wind turbines using computational fluid dynamics (CFD). The wind farm layout design is becoming increasingly important as the use of wind energy is steadily increasing. Among the many wind farm layout design parameters, the inter-turbine spacing is a key factor in the initial investment cost, annual energy production and maintenance cost. The inter-turbine spacing should be determined to maximize the annual energy production and minimize the wake effect, turbulence effect and fatigue load during the service lifetime of wind turbines. Therefore, some compromise between the aerodynamic power output of wind turbines and the inter-turbine spacing is needed. An actuator disc model with the addition of a momentum source was not used, and instead, a full 3-dimensional model with a tower and nacelle was used for CFD analysis because of its great technical significance. The CFD analysis results, such as the aerodynamic power output, axial direction wind speed change, pressure drop across the rotor of wind turbine, and wind speed deficit due to the wake effect with inter-turbine spacing variation, were studied. The results of this study can be applied effectively to wind farm layout design and evaluation.

Wind energy is one of the most promising renewable energy resources. BAWTs have been studied recently. BAWTs are a new technology trend to combine wind turbines with buildings and structures and it has several advantages compared with the conventional wind turbine such as minimization of electrical transmission loss and construction cost due to the distributed power sources and using buildings. In this paper, 110 kW class horizontal axis wind turbine is designed and CFD analysis is carried out with various wind speed. The results show aerodynamic power output of 110 kW class BAWT is higher than that of 110 kW class stand alone wind turbine due to the concentration effect caused by the wind speed acceleration between buildings. Flow characteristics are quite different for the existence of 110 kW class BAWT. These results can be applied to the research and development of BAWTs and high performance computing is indispensable.

Performance and internal flow of a direct drive turbine (DDT) model for wave power converter system is investigated experimentally. Three kinds of test turbine model are adopted for the examination. Test results show that rotational speed of test runner, differential pressure between front and rear nozzle passages and passage flow rate increase by the increase of wave height and wave period. Maximum output power and best efficiency of the test turbine model locate at the different rotational speed by wave height. Installation of front guide wall and rear water reservoir of the test turbine improves the turbine performance. Large passage vortex occurs both at the front and rear nozzle passages in turn by reciprocating flow in the internal flow passage of the turbine model.

Micro hydraulic power generation which has output of less or equal to 100kW is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydro power generator of which main concept is based on using differential water pressures in pipe lines, energy which was initially wasted by use of a reducing valve at an end of the pipeline, is collected by a turbine in the hydro power generator. A propeller shaped hydroturbine has been used in order to make use of this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydroturbine, output power, head, and efficiency characteristics due to the guide vane opening angle are examined in detail. Moreover, influences of pressure, tangential and axial velocity distributions on turbine performance are investigated by using a commercial CFD code.