• 제목/요약/키워드: Aeroelastic Effect

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CFD-CSD 연계 기법을 이용한 로터 블레이드 공력 및 소음 해석 (AERODYNAMIC AND NOISE CALCULATIONS OF HELICOPTER ROTOR BLADES USING LOOSE CFD-CSD COUPLING METHODOLOGY)

  • 강희정;김도형;위성용
    • 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.

Effect of sweep angle on bifurcation analysis of a wing containing cubic nonlinearity

  • Irani, Saied;Amoozgar, Mohammadreza;Sarrafzadeh, Hamid
    • Advances in aircraft and spacecraft science
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    • 제3권4호
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    • pp.447-470
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    • 2016
  • Limit cycle oscillations (LCO) as well as nonlinear aeroelastic analysis of a swept aircraft wing with cubic restoring moments in the pitch degree of freedom is investigated. The unsteady aerodynamic loading applied on the wing is modeled by using the strip theory. The harmonic balance method is used to calculate the LCO frequency and amplitude for the swept wing. Finally the super and subcritical Hopf bifurcation diagrams are plotted. It is concluded that the type of bifurcation and turning point location is sensitive to the system parameters such as wing geometry and sweep angle.

구조 감쇠 처리된 원통형 복합적층 패널의 플러터 해석 (Supersonic Flutter Analysis of Cylindrical Composite Panels with Structural Damping Treatments)

  • 신원호;오일권;이인
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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    • pp.131-134
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    • 2002
  • Supersonic flutter analysis of cylindrical composite panels with structural damping treatments has been performed using the finite element method based on the layerwise shell theory. The natural frequencies and loss factors of cylindrical viscoelastic composites are computed considering the effects of transversely shear deformation. The panel flutter of cylindrical composite panels is analyzed considering structural damping effect. Various damping characteristics for unconstrained layer damping, constrained layer damping, and symmetrically co-cured sandwich laminates are compared with those of an original base panel in view of aeroelastic stabilities.

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파라메타 각 변화를 고려한 힌지없는 헬리콥터 로우터의 공력탄성학적 안정성 (The Study on the Aeroelastic Stability of Hingeless Helicopter Rotor in Hover Considering Parametric Angle Changes)

  • 한창헌;김승조
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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    • pp.386-391
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    • 1998
  • The effect of the changes in parameter angles(precone, droop, sweep) on the lead-lag damping was focused on. Experiment was made with hingeless 4-blade rotors and NACA 0012 airfoil. For the measurement of the rotating natural frequencies and lead-lag damping, non-rotating swash plate was oscillated at the regressing lag mode frequency and the data were acquired after the excitation was cut off. Analysis was made using a finite element formulation based on Hamilton's principle. The main blade is assumed as elastic beams. Quasi-steady strip theory is used to obtain aerodynamic forces, and non-circulatory forces are also included.

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대형 풍력발전용 복합재료 블레이드의 개선된 등가 모델링 기법 (Improved Equivalent Beam Element Modeling Technique for Large Scale Wind-Turbine Composite Blade)

  • 김동현;박효근;김동만
    • 한국유체기계학회 논문집
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    • 제11권4호
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    • pp.32-37
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    • 2008
  • In this study, we have introduced an improved equivalent modeling technique for large scale composite wind-turbine blade. Conventional or general equivalent modeling procedure may give critical error in the analysis results because of geometric coupling effects. For the analyses of structural vibration and aeroelastic problems, the accuracy of equivalent structural models is very important since it can have high numerical efficiency and various practical applications. Three-dimensional realistic composite wind-turbine blade model is practically considered for numerical study. In order to validate the effect of the mass and the stiffness of the equivalent beam model, comparison study based on the natural vibration analysis has been conducted, and the accuracy levels of the conventional and modified equivalent modeling techniques are presented.

유도무기 날개 단면형상에 따른 초음속 및 극초음속 플러터 특성 (Supersonic and Hypersonic Flutter Characteristics for Various Typical Section Shapes of Missile Fin)

  • 김동현;김유성;김요한;오일권
    • 한국소음진동공학회논문집
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    • 제18권5호
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    • pp.496-502
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    • 2008
  • In this study, supersonic and hypersonic flutter characteristics have been analyzed for the various typical section shapes of missile fin configurations. Nonlinear flutter analyses are conducted considering the effect of moving shock waves. Computational fluid dynamic method is applied to accurately predict unsteady aerodynamic loads due to structural motions for the solution of aeroelastic governing equations. Commonly used typical section shapes of supersonic and hypersonic launch vehicles are considered in the present numerical study. Detailed flutter responses for four different typical section models are presented and the flutter characteristics are physically investigated.

Aerodynamic Flutter Control for Typical Girder Sections of Long-Span Cable-Supported Bridges

  • Yang, Yongxin;Ge, Yaojun
    • Wind and Structures
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    • 제12권3호
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    • pp.205-217
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    • 2009
  • Aerodynamic flutter control for long-span cable-supported bridges was investigated based on three basic girder sections, i.e. streamlined box girder section, box girder section with cantilevered slabs and two-isolated-girder section. Totally four kinds of aerodynamic flutter control measures (adding fairings, central-slotting, adding central stabilizers and adjusting the position of inspection rail) were included in this research. Their flutter control effects on different basic girder sections were evaluated by sectional model or aeroelastic model wind tunnel tests. It is found that all basic girder sections can get aerodynamically more stabled with appropriate aerodynamic flutter control measures, while the control effects are influenced by the details of control measures and girder section configurations. The control effects of the combinations of these four kinds of aerodynamic flutter control measures, such as central-slotting plus central-stabilizer, were also investigated through sectional model wind tunnel tests, summarized and compared to the flutter control effect of single measure respectively.

MW 규모 풍력 터빈의 기계적 하중 특성 해석 및 제어 (Mechanical Loads Analysis and Control of a MW Wind Turbine)

  • 남윤수;최한순
    • 한국정밀공학회지
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    • 제27권9호
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    • pp.26-33
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    • 2010
  • A multi-MW wind turbine is a huge mechanical structure, of which the rotor diameter is more or less than 100 m. Rotor blades experience unsymmetric mechanical loads caused by the interaction of incoming wind with the tower and wind shear effect. These mechanical loads are transferred to the entire structure of the wind turbine and are known as the major reasons for shortening the life span of the wind turbine. Therefore, as the size of wind turbine gets bigger, the mitigation of mechanical loads becomes more important issue in wind turbine control system design. In this paper, a concept of an individual pitch control(IPC), which minimizes the mechanical loads of rotor blades, is introduced, and simulation results using IPC are discussed.

CFD/CSD 통합 연계기법을 이용한 횡방향 곡률이 있는 날개의 가상 플러터 시험 (Virtual Flutter Test of a Spanwise Curved Wing Using CFD/CSD Integrated Coupling Method)

  • 오세원;이정진;김동현
    • 한국소음진동공학회논문집
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    • 제16권4호
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    • pp.355-365
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    • 2006
  • The coupled time-integration method with a staggered algorithm based on computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD) has been developed in order to demonstrate physical vibration phenomena due to dynamic aeroelastic excitations. Virtual flutter tests for the spanwise curved ing model have been effectively conducted using the present advanced computational method with high speed parallel processing technique. In addition, the present system can simultaneously give a recorded data file to generate virtual animation for the flutter safety test. The results for virtual flutter test are compared with the experimental data of wind tunnel test. It is shown from the results that the effect of spanwise curvature have a tendency to decrease the flutter dynamic pressure for the same flight condition.

Improvement of aeroelastic stability of hingeless helicopter rotor blade by passive piezoelectric damping

  • Yun, Chul-Yong;Kim, Seung-Jo
    • International Journal of Aeronautical and Space Sciences
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    • 제7권1호
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    • pp.54-64
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    • 2006
  • To augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover, piezoelectric shunt with a resistor and an inductor circuits for passive damping has been studied. A shunted piezoceramics bonded to a flexure of rotor blade converts mechanical strain energy to electrical charge energy which is dissipated through the resistor in the R-L series shunt circuit. Because the fundamental lag mode frequency of a soft-in-plane hingeless helicopter rotor blade is generally about 0.7/rev, the design frequency of the blade system with flexure sets to be so. Experimentally, the measured lag mode frequency is 0.7227/rev under the short circuit condition. Therefore the suppression mode of this passive damping vibration absorber is adjusted to 0.7227/rev. As a result of damping enhancement using passive control, the passive damper which consists of a piezoelectric material and shunt circuits has a stabilizing effect on inherently weakly damped lag mode of the rotor blades, at the optimum tuning and resistor condition.