본 연구는 2.5MW급 풍력발전기용 기어박스의 동특성 분석에 관한 것으로서, 유연핀(flexible pin) 채용에 따른 유성기어축의 미스얼라인먼트(misalignment) 개선여부와 충격하중에 따른 기어박스의 동응답 특성을 유한요소해석을 통해 고찰하였다. 내부의 복잡한 기어시스템의 하중전달을 정확하게 그리고 효과적으로 반영하기 위해 치접촉을 등가 치강성계수를 갖는 스프링요소와 물림률을 이용하여 모델링하였다. 기어의 등가 치강성계수는 기어치에 대한 변형해석을 통해 계산하였으며, 동특성 분석을 위해 기어박스 입력단에 충격 토오크를 부과하였다. 수치실험을 통해 등가 치강성모델의 타당성을 검증하였으며, 양단 그리고 일단 고정축과의 상대 비교를 통해 유연핀 적용에 따른 유성기어축의 미스얼라인먼트 개선여부를 확인할 수 있었다.

CFD(Computational Fluid Dynamics) analysis was carried out to analysis the air flow characteristics of vertical axis wind turbine system with accelerating device. Geometric arc angle of the accelerating device affects the air flow characteristics in the turbine with the effect of Coanda generated from the curved surface. Air velocity distributions with the device angle variation are compared. Flow velocity increases with the device length, and the accelerating device plays a key role in decreasing the air velocity in the wake flow region. Maximum air velocity variation becomes reduced with the accelerating device, and it is largely affected by the arc angle. These results are expected to be utilized in various ways to determine the shape of accelerating device for wind power generation system.

This research is to investigate the performance analysis of micro gas turbine for power generation with three different numbers of the nozzle vane in the micro gas turbine. Velocity, pressure. and temperature distributions of fluid over the flow domain of the turbine and turbulent kinetic energy of three different turbine blades are numerically calculated for the optimum design of turbine blade with two different rotational speeds of the turbine blade (10000 and 20000 RPM). Ultimately, the energy-efficient and maximum power-generated shape of the nozzle vane are determined through two different rotational speeds of the turbine with three shapes of the nozzle vane (6, 8, and 12 EA).

The performance of helical hydro turbine in water pipe line depends on the sectional shape of turbine blade, pitch angle of turbine blade, solidity and number of turbine blades, To investigate the effects of these design factors on the performance of helical hydro turbine, flow analysis was carried out by using commercial code ANSYS CFX version 14..5. From CFD analysis we obtained the optimum design factors which were the asymmetric blade shape of NACA4420, the pitch angle of 15 degrees and the solidity of 0.3. These results can be used for the actual design of sphere-shaped helical turbine in water pipe line.

Recently, wind power has received attention as one of remarkable renewable energy resources, and worldwide researches about wind power are actively being proceeded. Wind turbine tower has a major role for safety in the wind turbine systems. It is necessary for design tower structure to consider various environmental conditions. Earthquake, as one of the such environmental loads, is ground motion that applied to bottom of the tower structure and has a possibility of critical effect to the wind tower structure. There are various ways for seismic analysis, but design specifications that are in use do not suggest detailed method for seismic analysis. In this study, seismic responses are analyzed through different ways and the adequacy of seismic design methods is examined.

풍력발전 타워는 높은 세장비를 갖는 형상으로 인해 바람에 의해 발생하는 횡하중에 취약한 구조를 가지고 있기 때문에 바람은 풍력발전 타워를 설계하는데 있어서 중요한 설계요소 중 하나라고 할 수 있다. 본 논문에서는 타워 운송 편의성 향상을 위해 설계된 8각 및 6각 단면형상을 가지는 조립식 강관 타워 및 일반 원형 강관 타워의 일정 높이 이상에서부터 4개의 작은 기둥으로 분리되는 형상을 가지는 멀티기둥 강관 타워에 대한 2차원 단면모형 풍동실험과 3차원 모형 풍동실험을 수행하여 각 형상별 풍력계수를 산정하여 그 특성을 비교하였다. 또한 풍동실험 축소모형에 대한 CFD 해석을 수행하여 산정된 풍력계수값의 신뢰성을 확인하였으며, 마지막으로 실제스케일 풍력타워에 대한 CFD 해석을 수행하여 각 형상별 특성을 분석하였다.

This paper presents the dimensionless wall distance, y+ effect on SST turbulent model for wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine was used for the study, which the wind tunnel and structural test data has publicly available. The near wall treatment and turbulent characteristics have important role for proper CFD simulation. Most of the CFD development in this area is focused on advanced turbulence model closures including second moment closure models, and so called Low-Reynolds (low-Re) number and two-layer turbulence models. However, in many cases CFD aerodynamic predictions based on these standard models still show a large degree of uncertainty, which can be attributed to the use of the  -equation as the turbulence scale equation and the associated limitations of the near wall treatment. The present paper demonstrates the y+ definition effect on SST (Shear Stress Transport) turbulent model with advanced automatic near wall treatment model and Gamma theta transitional model for transition from lamina to turbulent flow using commercial ANSYS-CFX. In all cases the SST model shows to be superior, as it gives more accurate predictions and is less sensitive to grid variations.

This paper presents the structural model verification process of whole wind turbine blade including blade model which proposed in Part1 paper. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. In the Part1 of this paper, the processes of structural model development and verification process of blade only are introduced. The whole wind turbine composed by blade, rotor, nacelle and tower. Even though NREL has reported the measured values, the material properties of blade and machinery parts are not clear but should be tested. Compared with the other parts, the tower which made by steel pipe is rather simple. Since it does not need any considerations. By the help of simple eigen-value analysis, the accuracy of structural stiffness and mass value of whole wind turbine system was verified by comparing with NREL's reported value. NREL has reported the natural frequency of blade, whole turbine, turbine without blade and tower only models. According to the comparative studies, the proposed material and mass properties are within acceptable range, but need to be discussing in future studies, because our material properties of blade does not match with NREL's measured values.

In this study, flow characteristic of small vertical-axis wind turbine was performed to analysis the numerical analysis. Blade geometry in the wind turbine is NACA 6512-43, and various degrees of the wind turbine accelerator were adopted. Numerical models are used for the analysis with CFD program of Ansys fluent and RNG k-e turbulence model was used. Rotational speed value of the wind turbine in analysis condition were obtained by the experiment. When the wind turbine accelerator is equipped, exit velocity of wind turbine accelerator tended to increases. Also RPM of wind turbine is increase. And maximum RPM appeared that wind turbine accelerator in degree 60° is equipped.

This paper presents the structural model development and verification processes of wind turbine blade. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. The wind turbine assembled by blades, rotor, nacelle and tower. The wind blade connected to rotor. To make the whole turbine structural model, the mass and stiffness properties of all parts should be clear and given. However the wind blade, hub, nacelle, rotor and power generating machinery parts have difficulties to define the material properties because of the composite and assembling nature of that. Nowadays to increase the power generating coefficient and cost efficiency, the highly accurate aerodynamic loading evaluating technique should be developed. The Fluid-Structure Interaction (FSI) is the emerging new way to evaluate the aerodynamic force on the rotating wind blade. To perform the FSI analysis, the fluid and structural model which are sharing the associated interface topology have to be provided. In this paper, the structural model of blade development and verifying processes have been explained for Part1. In following Part2 paper, the processes of whole turbine system will be discussing.

본 연구에서는 BEMT(Blade Element Momentum Theory)에 의해 우선 정격 출력 100 kW인 수평축 조류 발전용 단일 터빈에 대한 기본 형상 설계를 진행하고, CFD 해석을 통해 블레이드 주변 유동특성 파악 및 출력 성능 예측을 하였다. 기본적인 에어포일은 FFA-W3-301, DU-93-W210, NACA-63418을 사용하였다. 이를 바탕으로 상반회전 터빈의 특성을 고찰한 결과, 설계 주속비 5.17에서 최대 출력계수는 0.495이며, 터빈의 출력은 101.82 kW를 얻었다.

Wind turbine tower has a very important role in wind turbine system as one of the renewable energy that has been attracting attention worldwide recently. Due to the growth of wind power market, advance and development of offshore wind system and getting huger capacity is inevitable. As a result, the vibration is generated at wind turbine tower by receiving constantly dynamic loads such as wind load and wave load. Among these dynamic loads, the mechanical load caused by the rotation of the blade is able to make relatively periodic load to the wind turbine tower. So natural frequency of the wind turbine tower should be designed to avoid the rotation frequency of the rotor according to the design criteria to avoid resonance. Currently research of the wind turbine tower, the precise research does not be carried out because of simplifying the structure of the other upper and lower. In this study, the effect of blade modeling differences are to be analyzed in natural frequency of wind turbine tower.

This paper presents a method for the assesment of thermal and vibration fatigues in integral exhaust manifold/turbine housing system. Most of failures on turbine housing are observed by thermal cyclic loads. In order to predict thermal failures by finite element analysis, we considered the temperature-dependent inelastic materials and transient temperature histories based on the thermal shock test. The results showed that the plastic strains of localized critical regions such as valve seat coincided well with crack locations from an endurance test. But, some failures around neck areas of turbine housing could not predict from thermal stress analysis. These cracks were originated due to the vibration excitations near resonance frequencies within engine operating ranges. The stress results of neck areas, which divided by temperature dependent yield stresses, from harmonic analysis showd a good agreement with experimental results.

단풍나무는 종족 번식을 목적으로 씨앗을 확산시키기 위해 바람을 이용한다. 모수에서 분리된 씨앗은 자동회전을 하면서 떨어지는데 이 회전을 통해 생성된 앞전 와류로 높은 양력을 발생시킴으로써 씨앗을 천천히 낙하시킨다. 단풍나무 씨앗의 자동회전 현상은 안정적인 공기 역학적으로 낙하 초기 자세에 상관없이 일정한 크기의 회전율과 낙하 속도를 갖고 있어서 산업적 응용 가능성도 크다. 본 연구에서는 단풍나무 씨앗의 자동회전 현상의 특성을 실험적으로 밝히고 이를 생체 모방하여 소형 풍력 터빈으로 개발할 가능성을 제시하고자 한다.

본 연구에서는 풍력터빈 블레이드에 대한 전산유체해석(CFD)을 수행하였다. 이를 위해서 National Renewable Energy Laboratory(NREL)에서 수행하였으며, 다양한 실험 및 해석결과가 공개된 실물크기 풍력터빈 블레이드인 NREL Phase VI를 해석대상으로 하였다. 상업용 범용 전산유체해석코드인 ANSYS-CFX와 파라매트릭 3D CAD 모델을 이용하여 해석을 수행하였으며, 실험결과와 비교하여 연구결과의 타당성을 검토하였다. 다양한 난류모델에 대한 비교연구를 통하여 Shear Stress Transport(SST) k − ω 난류모델의 정확성을 검증하였으며, 유동의 비정상상태를 최소화하기 위해서 0-각도 요(yaw)각을 고려하였다. NREL Phse VI 풍력터빈 블레이드는 2개의 날개를 가졌으며, 비선형 비틀림각과 선형 테이퍼가 고려되었다. 풍력터빈 블레이드가 주축에 대해서 회전하기 때문에 상대속도는 스팬에 대해서 비선형의 관계를 가진다. 따라서 받음각(angle of attack)을 최소화하기 위해서 비선형 비틀림각이 고려되었다. 해석결과의 3차원 풍력특성을 분석하기 위해서, 각 단면의 압력계수 및 이를 적분하여 풍력계수(수직, 접선, 추력, 회전력)를 계산하였다. 풍력터빈 블레이드의 회전속도는 72 RPM으로 고정한 상태에서 다양한 풍속(5m/s, 7m/s, 10m/s, 13m/s, 15m/s, 20m/s, 25m/s) 상태를 해석하였다. 해석결과와 풍동실험결과는 모든 풍속에 대해서 근사한 수치를 나타냈으며, 높은 풍속에서의 풍하면 박리현상에 대한 정확한 유동특성을 해석할 수 있었다.

This research is to investigate the performance analysis of turbine for power generation with three different numbers of the nozzle vane in the turbine. Velocity, pressure. and temperature distributions of fluid over the flow domain of the turbine are numerically calculated for the optimum design of nozzle with two different rotational speeds of the turbine blade (1000 and 1500 RPM). Ultimately, the energy-efficient and maximum power-generated shape of the nozzle vane are determined through three different maximum Mach number of the flow with three shapes of the nozzle vane (10, 18, and 24 EA).