• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.275-282
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• 2007

In this study, a fluid-structure interaction (FSI) analysis system has been developed in order to evaluate the turbine cascade performance with blade structural deformation effect. Relative movement of the rotor with respect to stator is reflected by modeling independent two computational domains. To consider the deformed position of rotor airfoil, dynamic moving grid method is applied. Reynolds-averaged Navier-Stokes equations with one equation Spalart-Allmaras and two-equation SST $k-{\varepsilon}$ turbulence models are solved to predict unsteady fluid dynamic loads. A fully implicit time marching scheme based on the Newmark direct integration method with high artificial damping is used to compute the fluid-structure interaction problem. Cascade performance evaluations for different elastic axis positions are presented and compared each other. It is importantly shown that the predicted aerodynamic performance considering structural deformation effect of blade can show some deviations compared to the data generally computed from rigid blade configurations and the position of elastic axis also tend to give sensitive effect.

• 한국항공우주학회지
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• 제36권1호
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• pp.72-78
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• 2008

본 연구에서는 블레이드 구조 변형 효과를 고려하여 스테이터-로터 상호간섭 케스케이드 모델의 성능평가를 위한 유체-구조 연계해석 시스템을 개발하였다. 고정된 스테이터와 회전하는 로터는 상호간섭 영향이 유동해석에 고려되었으며, 레이놀즈-평균화 난류 방정식인 Spalart-Allmaras 모델과 k-ω SST 난류 모델이 압축성 유동박리 효과를 고려한 유동하중을 예측하기 위해 적용되었다. 정적인 유체-구조 연계해석과 수렴율 증진을 효과적으로 수행하기 위하여 큰 인공 감쇠를 가지는 연계 Newmark 시간적분 기법을 적용하였다. 수치실험을 통해 탄성축 위치에 따른 구조변형 효과가 케스케이드 성능에 미치는 영향을 파악하였다. 구조변형 효과가 고려된 경우 일반적인 강체 블레이드 모델에 대한 성능예측 결과와 다소 차이가 유발될 수 있음을 보였으며 공력탄성학적 영향을 고찰하였다.

• International Journal of Aerospace System Engineering
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• 제8권1호
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• pp.1-13
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• 2021

Contra-rotating fan is comprised of two rotors which are rotating in the opposite direction. The fan stages are named rotor-1 and rotor-2. Benefits from the use of contra rotation are in terms of better efficiency and improved thrust to weight ratio. Failure of contra-rotating fan stage blade in-service results in safety risks, repair costs, and revenue losses. This paper focuses on the vibration analysis and one way fluid-structure interaction of high aspect ratio, low speed contrarotating fan rotors. Modal analysis and modal pre-stress analysis of contra-rotating fan rotors were carried out to calculate the natural frequencies, One way fluid-structure interaction (FSI) was carried out where the computational analysis of the blades was performed using ANSYS CFX. The boundary conditions for CFD analysis were considered from the actual experimental velocity flow field at the inlet and pressure outlet. Based on the results obtained from the CFD analysis, the structural analysis such as deformation and Von-Misses stresses was carried out by using the finite element method (FEM) with ANSYS. The results provide necessary guidelines for the safe running of the contra-rotating fan. The analysis also will be helpful to understand the change of flow behavior due to a rotor deformation.

• 한국전산유체공학회지
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• 제19권3호
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• pp.62-68
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• 2014

The aerodynamic and noise calculations were performed through the CFD-CSD loose coupling methodology. In the loose coupling process, the trimmed rotor airloads were predicted by the in-house CFD code based on unstructured overset meshes, and the trim of the rotorcraft and the aeroelastic deformation of rotor blades were accounted with the CAMRAD II rotorcraft comprehensive code. The set of codes was used to analyze the HART-II baseline test condition. The effect of grid resolution and time step was examined and the loose coupling approach was found to be stable and convergent for the case. Comparison of the resulting sectional airloads, structural deformations, the noise carpets and the wake geometry with experimentally measured data was presented and showed the good agreement.

• International Journal of Aeronautical and Space Sciences
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• 제16권1호
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• pp.110-122
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• 2015

In this paper, the unsteady aerodynamics and blade structural dynamics of an experimental bearingless rotor were analyzed. Due to the multiple load path and nonlinear behavior of a bearingless rotor, sophisticated structural modeling and structural-aerodynamic coupled analysis is required. To predict the internal load and deformation of an experimental bearingless rotor, trim analysis was implemented. The results showed good agreement when compared with those predicted by CAMRAD II the rotorcraft comprehensive analysis. It is possible to extend the present structural-aerodynamic combined analysis to further advanced configurations of the bearingless rotor in the future.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.121-124
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• 2004

The purpose of this study is to define the optimized layer pattern of composite wind turbine blade by using a commercial FEM program and to perform the fatigue test of T-Bolt. FEM analysis is done by using a PATRAN and ABAQUS to get a information about stress distribution ,critical deformation shape and get a critical load factor in local buckling analysis. As a result of the linear and nonlinear structural analysis, layer pattern of blade was optimized. T-Bolt is a connecting part of wind turbine blade and rotor hub, therefore T-bolt is cirtical part of wind turbine blade. T-bolt fatigue test is conducted to get a information of life cycle of T-bolt. The test is done by using a hydraulic actuator system

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.24-34
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• 2007

Closed-loop active twist control of integral helicopter rotor blades is investigated in this paper for reducing hub vibration induced in forward flight. A four-bladed fully articulated integral twist-actuated rotor system has been designed and tested successfully in wind tunnel in open-loop actuation. The integral twist deformation of the blades is generated using active fiber composite actuators embedded in the composite blade construction. An analytical framework is developed to examine integrally twisted helicopter blades and their aeroelastic behavior during different flight conditions. This aeroelastic model stems from a three-dimensional electroelastic beam formulation with geometrical-exactness, and is coupled with finite-state dynamic inflow aerodynamics. A system identification methodology that assumes a linear periodic system is adopted to estimate the harmonic transfer function of the rotor system. A vibration minimizing controller is designed based on this result, which implements a classical disturbance rejection algorithm with some modifications. Using the established analytical framework, the closed-loop controller is numerically simulated and the hub vibratory load reduction capability is demonstrated.

• 한국안전학회지
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• 제25권4호
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• pp.1-6
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• 2010

Wind power system is composed by 3 major parts, rotor blade, nacelle and tower. Especially, the nacelle cover has an important role to prevent the component of nacelle and rotor from an extreme external circumstance. Therefore it is necessary to analyze and evaluate the stress distribution and deformation for them in the design level. There are two major points in nacelle cover analysis. The one is nacelle cover itself and the other is cover support structure. According to GL specification, this study shows the result that CFRP nacelle cover of wind turbine satisfies the strength and deformation through numerical analysis using the commercial finite element analysis program.

• 대한기계학회논문집A
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• 제38권6호
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• pp.691-698
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• 2014

본 논문에서는 복합재료를 이용하여 플렉스빔과 토크튜브를 제작하기 위한 공정과 기본 물리량 시험과정을 소개하였다. 플렉스빔과 토크튜브는 헬리콥터에 적용되는 무베어링 로터 허브 시스템을 구성하기 위한 핵심 구성품이다. 토크튜브는 블레이드의 피치각을 변화시키기 위한 조종력을 전달하며, 플렉스빔은 구조적인 변형을 통해 플랩, 래그 및 페더링 힌지를 구현하는 기능을 담당한다. 지상회전시험을 수행하기에 앞서 플렉스빔과 토크튜브 및 블레이드의 플랩강성, 래그강성 및 토션강성을 측정하기 위한 기본 물리량 시험을 수행하였다. 또한, 해석을 통해 예측된 단면 강성과 기본 물리량을 통해 획득된 강성 값을 비교하였으며, 그 결과를 통해 복합재료로 제작된 플렉스빔과 토크튜브가 구조적인 강성 요구도를 만족함을 확인할 수 있었다.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1067-1074
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• 2010

본 논문에서는, 운전조건에서의 저압최종단 블레이드에 대하여 약결합 유체-구조 연계해석기법을 이용한 해석이 수행되었다. 저압터빈 최종단에 대한 해석이전에 경계조건에 대한 검증을 위하여 15도 후퇴익과 NASA Rotor 37을 대상으로 예비해석이 수행되었다. 각각의 해석결과들을 기존 문헌들과 비교하였다. 15도 후퇴익에 대한 안정상태와 불안정상태에서 동적 FSI해석이 수행되었다. 해석결과 변위가 일정한 안정상태에 비하여 고속에서는 0.05 초 만에 발산하는 결과를 산출하였다. NASA Rotor 37의 정상상태 해석결과를 바탕으로 정적 동적 FSI 해석을 수행하여 뒷전의 변형크기에 대하여 정적 FSI 결과와 동적 FSI간의 차이가 있음을 확인하였다. 저압 최종단 블레이드의 형상측정 및 동특성시험을 바탕으로 해석모델을 생성하였다. 이를 바탕으로, 운전조건에서 저압최종단 블레이드에 대한 정적 유체-구조 연계해석을 성공적으로 수행하였다.