• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.190-193
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• 2005

The purpose of the present study is to design a 500W-class micro scale composite wind turbine blade. The blade airfoil of FFA-W3-211 was selected to meet Korean weather condition. The skin-spar-f Dam sandwich type structure was adopted for improving buckling and vibration damping characteristics. The design loads were determined at wind speed of 25m/s. and the structural analysis was performed to confirm safety and stability from strength. buckling and natural frequency using the finite element code. NISA II [6]. The prototype was manufactured using the hand-lay up method and it was experimently tested using the sand bag loading method. In order to evaluate the design results. it was compared with experimental results. According to comparison results. the estimated results such as compressible stress. max tip deflection natural frequency and buckling load factor were well agreed with the experimental results.

• 신재생에너지
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• 제4권3호
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• pp.45-50
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• 2008

GFRP based composite rotor blades were developed for 750 kW & 2 MW wind turbines. The blade sectional geometry was designed to have a general shell-spar and shear web structure. For verifying the structural safety under all relevant extreme loads specified in the GL guidelines, the structural analysis of the rotor blades was performed using commercial FEM codes. The static load carrying capacity, blade tip deflections and natural frequencies were evaluated to satisfy the strength and stability requirements. Full-scale proof tests of rotor blades were carried out with optical fiber sensors for real-time condition monitoring. Finally, the prototype of each rotor blade passed all proof tests for GL certification.

• 드라이브 ㆍ 컨트롤
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• 제21권1호
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• pp.53-58
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• 2024

With the recent development of intelligence and automation technologies for construction machinery, the demand for safety and efficiency of road-cutting operations has continued to increase. In response to this, a double-blade road cutter has been developed that can automatically cut roads. However, a double-blade road cutter has a load difference between the two blades due to the ground and wear conditions of the cutting blades. The difference in load between the two blades distorts the direction of travel of the cutter. In this study, a vision sensor-based driving guide technology was developed to correct the driving path of road cutters. In addition, we developed a load-sensing technology that detects blade loads in real-time and controls driving speed in the event of overload.

• 한국항공우주학회지
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• 제37권7호
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• pp.634-641
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• 2009

본 연구에서는 개별 블레이드의 복합재료 물성의 불확실성에 의해 발생하는 허브 진동하중의 특성에 대해 고찰하였다. 몬테-카를로 시뮬레이션 기법을 적용하여 시험에서 얻은 복합재료의 기계적 특성으로부터 블레이드의 단면 강성계수에 대한 확률적 분포를 구하였다. 단면 강성계수의 평균 및 표준편차 값을 이용하여 통합 공탄성 해석 코드의 입력 파일을 생성하고, 이로부터 허브 작용 하중을 구하였다. 복합재료 블레이드의 불확실성 효과는 필연적으로 로터 시스템의 상이성을 야기함을 보였다. 또한 개별 강성계수의 변화에 대한 허브 진동 응답의 특성을 확인하였다.

• 풍력에너지저널
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• 제5권1호
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• pp.22-32
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• 2014

The structural design of a wind turbine must show the verification of the structural integrity of all load-carrying components. Also, design load calculations shall be performed using appropriate and accurate methods. In this study, advanced numerical approach for the calculation of design loads based on unsteady computational fluid dynamics (CFD) is presented considering extreme design load conditions such as the extreme coherent gust (ECG) and the 50 year extreme operating gust (EOG). Unsteady aerodynamic loads are calculated based on Reynolds average Navier-Stokes (RANS) equations with shear-stress transport k-ω(SST k-ω) turbulent model. A full three-dimensional 5 MW offshore wind-turbine model with rotating blades, hub, nacelle, and tower configuration is practically considered and its aerodynamic interference effect among blades, nacelle, and tower is also accurately considered herein. Calculated blade loads based on unsteady CFD method with respect to blade azimuth angle are compared with those by NREL FAST code and physically investigated in detail.

• 한국유체기계학회 논문집
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• 제18권6호
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• pp.63-70
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• 2015

This paper proposes a novel airfoil named "KA2" for the blade of the wind turbine systems. Dynamic loads characteristics are analyzed and compared using aerodynamic data of ten airfoils including the proposed airfoil. The blade is divided into the sixteen elements in the longitudinal direction of the blade for applying the Blade Element Method Theory (BEMT) method, and in each element, torque, thrust, and pitching moment are calculated using turbulent time varying wind speed and aerodynamic data of each wing. Additionally, each force and torque is accumulated in the whole region of the blade for the estimation of representative values. The magnitude of such forces is comparatively analyzed for different airfoils. The angle of attack is constant below the rated wind speed due to the fact that the tip speed ratio is kept at the constant value, and it increases in the region of over rated wind speed as the tip speed ratio decreasing with constant rated rpm and increasing wind speed. Such increase in the angle of attack causes the changes of the force acting on the airfoil with different characteristics of lift and drag in the stall region of each different airfoil. Even though the mean wind speed is in the rated speed in a given time, because of the turbulence, it has either the over rated or under rated speed most of the time. Furthermore, the dynamic properties of each force are analyzed in this rated wind speed in order to objectively understand the dynamic properties of the blades which are designed based on the different airfoils. These dynamic properties are also compared by the standard deviation of time varying characteristics. Moreover, the output characteristics of the wind turbine are investigated with different airfoils and wind speeds. Based on these investigations, it was revealed that the proposed airfoil (KA2) is well applicable to the blade with passive pitch control system.

• 한국항공우주학회지
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• 제30권8호
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• pp.103-111
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• 2002

열하중과 원심력을 고려한 발전용 터빈 블레이드의 정상 상태 크리프 해석을 수행하였다. 3차원 터빈 블레이드 유한 요소 모델에 대하여 크리프 변형률과 응력을 계산하고 수치적 방법에 의해 크리프 수명을 예측하였다. 약 200시간 정도의 크리프 해석 결과 GTD111 터빈 블레이드는 아직 파손 응력에 도달하지 않았으며, 크리프 응력은 시간이 경과함에 따라 점차 이완되고 있다. 터빈 블레이드의 최대 크리프 변형률은 익형의 압력면 끝단에서 발생하며 수치적 방법에 의해 약 50,000 시간 이후에 파손 변형률에 도달할 것이다. 따라서 현재 터빈의 기동 중 블레이드는 크리프에 의한 손상을 입지 않는다.

• 한국항공우주학회지
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• 제35권6호
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• pp.496-502
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• 2007

본 논문에서는 비선형적 다물체 시스템의 유한요소 해석프로그램인 DYMORE의 새로운 버전을 이용하여 압전 재료(piezoelectric)를 삽입한 능동 비틀림 로터(Active Twist Rotor)의 개별 블레이드 제어(Individual Blade Control)에 의한 로터 블레이드의 진동 감소 효과를 해석하고 이를 풍동실험 및 이전 버전의 DYMORE 결과와 비교하였다. 본 연구에서는 로터 허브와 네 개의 블레이드만으로 구성된 단순한 로터시스템과 스워시 판, 피치링크 등을 모두 포함하는 개선된 로터시스템에 대한 해석이 각각 수행되었다. 사용된 실험 결과 자료들은 NASA Langley의 Transonic Dynamics Tunnel(TDT)에서 수행되었던 결과들을 사용하였다. 그 결과 새로운 버전의 DYMORE를 이용한 경우 실험값과는 여전히 차이가 있지만 이전 버전의 DYMORE를 통해 얻어진 수치해석 결과에 비해서 오차가 개선되는 것을 확인할 수 있었다. 또한 개별 블레이드 제어 방식의 로터 시스템의 모델링을 수행하고 전진 비행 시의 진동 하중 감소 효과를 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.256-263
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• 2008

The assumed modes method is developed to derive a set of linear differential equations describing the motion of a flexible wind turbine blade and to propose an approach to investigate the forced responses result from various wind excitations. In this work, we have adopted Euler beam theory and considered that the root of the blade is clamped at the rigid hub. And the aerodynamic parameters and forces are determined based on Blade Element Momentum (BEM) theory and quasi-steady airfoil aerodynamics. Numerical calculations show that this method gives good results and it can be used fur modeling and the forced vibration analysis including the coupling effect of wind-turbine blades, as well as turbo-machinery blades, aircraft propellers or helicopter rotor blades which may be considered as straight non-uniform beams with built-in pre-twist.

• Advances in Energy Research
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• 제6권1호
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• pp.35-54
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• 2019

A successful blade design must satisfy some criterions which might be in conflict with maximizing annual energy yield for a specified wind speed distribution. These criterions include maximizing power output, more resistance to fatigue loads, reduction of tip deflection, avoid resonance and minimize weight and cost. These criterions can be satisfied by modifying the geometrical parameters of the blade. This study is dedicated to the aerodynamic assessment of a 20 kW horizontal axis wind turbine operating with two possible airfoils; that is $G{\ddot{o}}ttingen$ 413 and NACA 2415 airfoils (the Gottingen airfoil never been used in wind turbines). For this study parameters such as chord (constant, tapered and elliptic), twist angle (constant and linear) are varied and applied to the two airfoils independently in order to determine the most adequate blade configuration that produce the highest annual energy output. A home built numerical code based on the Blade Element Momentum (BEM) method with both Prandtl tip loss correction and Glauert correction, X-Foil and Weibull distribution is developed in Matlab and validated against available numerical and experimental data. The results of the assessment showed that the NACA 2415 airfoil section with elliptic chord and constant twist angle distributions produced the highest annual energy production.