• 한국가시화정보학회지
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• 제8권2호
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• pp.51-55
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• 2010

Flow characteristics of a free-horizontal-axis-turbine (FHAT) current power generation system have been investigated by the use of a volumetric PTV. Three types of FHAT system (S50, SE50, S65) have been tested under the current speed 1.35 knot, 1.5 knot and 2 knot. The width of the blade installed around the body is 50 mm. Based upon the power generation characteristics of the FHAT, the flow features of the blade have been investigated. Among the three models it has been verified that the S65 is the most appropriate for power generations.

• 신재생에너지
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• 제1권1호
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• pp.54-63
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• 2005

A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady airloads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interaction. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NRELand SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.17-27
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• 2017

The treatment of rotor wake has been a critical issue in the field of the rotor aerodynamics. This paper presents a new free wake model for the unsteady analysis for a wind turbine. A blade-wake-tower interaction is major source of unsteady aerodynamic loading and noise on the wind turbine. However, this interaction can not be considered in conventional free wake model. Thus, the free wake model named Finite Vortex Element (FVE hereafter) was devised in order to consider the interaction effects. In this new free wake model, the wake-tower interaction was described by dividing one vortex filament into two vortex filaments, when the vortex filament collided with a tower. Each divided vortex filaments were remodeled to make vortex ring and horseshoe vortex to satisfy Kelvin's circulation theorem and Helmholtz's vortex theorem. This model was then used to predict aerodynamic load and wake geometry for the horizontal axis wind turbine. The results of the FVE model were compared with those of the conventional free wake model and the experimental results of SNU wind tunnel test and NREL wind tunnel test under various inflow velocity and yaw condition. The result of the FVE model showed better correlation with experimental data. It was certain that the tower interaction has a strong effect on the unsteady aerodynamic load of blades. Thus, the tower interaction needs to be taken into account for the unsteady load prediction. As a result, this research shows a potential of the FVE for an efficient and versatile numerical tool for unsteady loading analysis of a wind turbine.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.33-36
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• 2005

A critical issue in the field of the rotor aerodynamics is the treatment of the wake. The wake is of primary importance in determining overall aerodynamic behavior, especially, a wind turbine blade includes the unsteady air loads problem. In this study, the wake generated by blades are depicted by a free wake model to analyse unsteady loading on blade and a new free wake model named Finite Vortex Element(FVE hereafter) is devised in order to include a wake-tower interact ion. In this new free wake model, blade-wake-tower interaction is described by cutting a vortex filament when the filament collides with a tower. This FVE model is compared with a conventional free wake model and verified by a comparison with NREL and SNU wind tunnel model. A comparison with NREL and SNU data shows validity and effectiveness of devised FVE free wake model and an efficient.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.95-104
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• 2022

Micro hydropower is a readily available renewable energy source that can be harvested utilizing hydrokinetic turbines from shallow water canals, irrigation and industrial channel flows, and run-off river stream flows. These sources generally have low head (<1 m) and low velocity which makes it difficult to harvest energy using conventional turbines. A horizontal-axis screw turbine was designed and numerically tested to extract power from such low-head water sources. The 3-bladed screw-type turbine is placed horizontally perpendicular to the incoming flow, partially submerged in a narrow water channel at no-head condition. The turbine hydraulic performances were studied using Computational Fluid Dynamics models. Turbine design parameters such as the shroud diameter, the hub-to-shroud ratios, and the submerged depths were obtained through a steady-state parametric study. The resulting turbine configuration was then tested by solving the unsteady multiphase free-surface equations mimicking an actual open channel flow scenario. The turbine performance in the shallow channel were studied for various Tip Speed Ratios (TSR). The highest power coefficient was obtained at a TSR of 0.3. The turbine was then scaled-up to test its performance on a real site condition at a head of 0.3 m. The highest power coefficient obtained was 0.18. Several losses were observed in the 3-bladed turbine design and to minimize losses, the number of blades were increased to five. The power coefficient improved by 236% for a 5-bladed screw turbine. The fluid losses were minimized by increasing the blade surface area submerged in water. The turbine performance was increased by 74.4% after dipping the turbine to a bottom wall clearance of 30 cm from 60 cm. The final output of the novel horizontal-axis screw turbine showed a 2.83 kW power output at a power coefficient of 0.63. The turbine is expected to produce 18,744 kWh/year of electricity. The design feasibility test of the turbine showed promising results to harvest energy from small hydropower sources.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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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.

• 한국전자통신학회논문지
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• 제7권1호
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• pp.81-89
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• 2012

범용적으로 사용되고 있는 수평형 풍력 터빈(HAWT)은 블레이드가 장착된 터빈이 회전부인 너셀에 고정되어 타워의 최상단에 지지되는 구조이다. 터빈에서 생산되는 전력은 너셀 내부에서 증속기를 통하여 발전기로 들어가게 된다. 발전기에서 생산되는 전력은 타워를 통해서 지상과 송전선으로 연결되므로 너셀의 요잉이 발생하는 경우 송전선의 꼬임이 발생하게 된다. 따라서 이를 방지하기 위한 슬립링이나 추가적인 요잉 제어 알고리즘이 필요한 단점이 있다. 제안하는 새로운 구조의 HAWT는 베벨기어와 중공축을 이용하여 송전선 문제를 해결하였다. 또한, 병렬로 접속된 두개의 발전기를 이용하여 요잉이 용이할 뿐 아니라 생산 전력을 분산시킴으로써 인버터의 용량을 줄일 수 있다. MPPT 알고리즘과 요잉 제어를 수행하는 시뮬레이션을 통해서 제안하는 구조가 풍력 발전에 효과적임을 보였다.

• 한국음향학회지
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• 제21권2호
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• pp.134-141
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• 2002

본 연구에서 곡선 와동 요소와 CVC (Constant Vorticity Contour) 후류 모델이 수평축 풍력 터빈의 공력 성능 및 소음을 예측하기 위해 사용되었다. 또한 2차 회귀에 근거하여 회전수의 예측을 하였다. 광대역 소음을 예측은 경험식에 근거한 방법을 사용하였다. 직선 와동요소 대신에 BCVE (Basic Curved Vortex Element)와 SIVE(Self Induction Vortex Element)를 사용하는 곡선 와동 요소를 사용하였으며 CVC 후류 모델에서 와동의 강도는 블레이드의 스팬방향 및 와동을 따라서 일정하다고 가정하였다. 이렇게 만들어진 자유 후류는 와동 격자를 대치한다. 본 방법은 여타의 방법에 비해 휠씬 적은 계산 시간을 요구하며 후류의 정확한 구조를 모사할 수 있었다. 검증을 위해서는 김준모의 실험과 Zond사의 Z-40FS의 모델을 성능 예측 결과와 WTS-4와 USWP를 소음 예측 결과와 비교하였다. 계산 결과는 실제의 실험치와 잘 일치하는 것으로 나타났다.