• Title, Summary, Keyword: aero-elasticity

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Non-linear aero-elastic response of a multi-layer TPS

  • Pasolini, P.;Dowell, E.H.;Rosa, S. De;Franco, F.;Savino, R.
    • Advances in aircraft and spacecraft science
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    • v.4 no.4
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    • pp.449-465
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    • 2017
  • The aim of the present work is to present a computational study of the non-linear aero-elastic behavior of a multi-layered Thermal Protection System (TPS). The severity of atmospheric re-entry conditions is due to the combination of high temperatures, high pressures and high velocities, and thus the aero-elastic behavior of flexible structures can be difficult to assess. In order to validate the specific computational model and the overall strategy for structural and aerodynamics analyses of flexible structures, the simplified TPS sample tested in the 8' High Temperature Tunnel (HTT) at NASA LaRC has been selected as a baseline for the validation of the present work. The von $K{\acute{a}}rm{\acute{a}}n^{\prime}s$ three dimensional large deflection theory for the structure and a hybrid Raleigh-Ritz-Galerkin approach, combined with the first order Piston Theory to describe the aerodynamic flow, have been used to derive the equations of motion. The paper shows that a good description of the physical behavior of the fabric is possible with the proposed approach. The model is further applied to investigate structural and aero-elastic influence of the number of the layers and the stitching pattern.

Wind Turbine Simulation Program Development using an Aerodynamics Code and a Multi-Body Dynamics Code (풍력발전시스템의 유연체 다물체 동역학 시뮬레이션 프로그램 개발)

  • Song, Jin-Seop;Rim, Chae-Whan;Nam, Yong-Yun;Bae, Dae-Sung
    • New & Renewable Energy
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    • v.7 no.4
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    • pp.50-57
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    • 2011
  • A wind turbine simulation program for the coupled dynamics of aerodynamics, elasticity, multi-body dynamics and controls of turbine is newly developed by combining an aero-elastic code and a multi-body dynamics code. The aero-elastic code, based on the blade momentum theory and generalized dynamic wake theory, is developed by NREL(National Renewable Energy Laboratory, USA). The multi-body dynamics code is commercial one which is capable of accounting for geometric nonlinearity and twist deflection. A turbulent wind load case is simulated for the NREL 5-MW baseline wind turbine model by the developed program and FAST. As a result, the two results agree well enough to verify the reliability of the developed program.

Influence of failed blade-pitch-control system to FOWT by aero-elastic-control-floater-mooring coupled dynamic analysis

  • Bae, Yoon Hyeok;Kim, Moo-Hyun
    • Ocean Systems Engineering
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    • v.3 no.4
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    • pp.295-307
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    • 2013
  • More FOWTs (floating offshore wind turbines) will be installed as relevant regulations and technological hurdles are removed in the coming years. In the present study, a numerical prediction tool has been developed for the fully coupled dynamic analysis of FOWTs in time domain including aero-loading, tower elasticity, blade-rotor dynamics and control, mooring dynamics, and platform motions so that the influence of rotor-control dynamics on the hull-mooring performance and vice versa can be assessed. The developed coupled analysis program is applied to Hywind spar design with 5 MW turbine. In case of spar-type floaters, the control strategy significantly influences the hull and mooring dynamics. If one of the control systems fails, the entire dynamic responses of FOWT can be significantly different. Therefore, it is important to maintain various control systems in a good operational condition. In this regard, the effects of failed blade pitch control system on FOWT performance including structural and dynamic responses of blades, tower, and floater are systematically investigated. Through this study, it is seen that the failure of one of the blade pitch control system can induce significant dynamic loadings on the other blades and the entire FOWT system. The developed technology and numerical tool are readily applicable to any types of floating wind farms in any combinations of irregular waves, dynamic winds, and steady currents.

STUDY OF RELIABILITY BASED FLEXIBLE WING SHAPE DESIGN OPTIMIZATION (신뢰성을 고려한 유연 날개 형상 최적 설계에 대한 연구)

  • Kim S.W.;Kwon J.H.
    • Journal of computational fluids engineering
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    • v.11 no.1
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    • pp.21-28
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    • 2006
  • Reliability Based Design Optimization(RBDO) is one of the optimization methods that minimize the product failure due to small changes of operating conditions or process errors. It searches the optimum that satisfies the safety margin of each constraint, and it gives stable and reliable designs. However, RBDO requires many times oj computational efforts compared with the conventional deterministic optimization(DO) to evaluate the probability of failure about each constraint, therefore it is hard to apply directly to large-scaled problems such as a flexible wing shape design optimization. For the efficient reliability analysis, the approximate reliability analysis method with the two-point approximation(TPA) is proposed In this study, the lift-to-drag ratio maximization designs are performed with 3-dimensional Navier-Stokes analysis and NASTRAN structural analysis, and the optimization results about the deterministic, FORM and SORM are compared.

Floating offshore wind turbine system simulation

  • Shi, Wei;Park, Hyeon-Cheol;Jeong, Jin-Hwa;Kim, Chang-Wan;Kim, Yeong-Chan
    • 한국신재생에너지학회:학술대회논문집
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    • pp.466-472
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    • 2009
  • Offshore wind energy is gaining more and more attention during this decade. For the countries with coast sites, the water depth is significantly large. This causes attention to the floating wind turbine. Offshore wind turbines are designed and analyzed using comprehensive simulation codes that account for the coupled dynamics of the wind inflow, aerodynamics, elasticity and controls of the wind turbine, along with the incident waves, sea current, hydrodynamics, and foundation dynamics of the support structures. In this work, a three-bladed 5MW upwind wind turbine installed on a floating spar buoy in 320m of water is studied by using of fully coupled aero-hydro-servo-elastic simulation tool. Specifications of the structures are chosen from the OC3 (Offshore Code Comparison Collaboration) under "IEA Wind Annex XXIII-subtask2". The primary external conditions due to wind and waves are simulated. Certain design load case is investigated.

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Rotor-floater-mooring coupled dynamic analysis of mono-column-TLP-type FOWT (Floating Offshore Wind Turbine)

  • Bae, Y.H.;Kim, M.H.
    • Ocean Systems Engineering
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    • v.1 no.1
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    • pp.95-111
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    • 2011
  • Increasing numbers of floating offshore wind turbines are planned and designed these days due to their high potential in massive generation of clean energy from water depth deeper than 50 m. In the present study, a numerical prediction tool has been developed for the fully-coupled dynamic analysis of FOWTs in time domain including aero-blade-tower dynamics and control, mooring dynamics, and platform motions. In particular, the focus of the present study is paid to the dynamic coupling between the rotor and floater and the coupled case is compared against the uncoupled case so that their dynamic coupling effects can be identified. For this purpose, a mono-column mini TLP with 1.5MW turbine for 80m water depth is selected as an example. The time histories and spectra of the FOWT motions and accelerations as well as tether top-tensions are presented for the given collinear wind-wave condition. When compared with the uncoupled analysis, both standard deviations and maximum values of the floater-responses/tower-accelerations and tether tensions are appreciably increased as a result of the rotor-floater dynamic coupling, which may influence the overall design including fatigue-life estimation especially when larger blades are to be used.

Fluid-Structure Interaction Analysis of High Aspect Ratio Wing for the Prediction of Aero-elasticity (유체-구조 연계 해석기법을 이용한 세장비가 큰 비행체 날개의 공탄성 해석)

  • Lee, Ki-Du;Lee, Young-Shin;Lee, Dae-Yearl;Lee, In-Won
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.6
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    • pp.547-556
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    • 2010
  • For the safety of aircraft and accuracy of bombs, many companies have researched the new concept of adaptive kit to flying-bombs. For the long distance flying, it's normally used deployed high-aspect ratio wing because of limited volume. The probabilities of large elastic deformation and flutter are increased due to decreased stiffness of high-aspect ratio wing. In this paper, computational fluid dynamics and computational structure dynamics interaction methodology are applied for prediction of aerodynamic characteristics. FLUENT and ABAQUS are used to calculate fluid and structural dynamics. Code-bridge was made base on the compactly supported radial basis function to execute interpolation and mapping. There are some differences between rigid body and fluid-structure interaction analysis which are results of aerodynamics characteristics due to structural deformation. Small successive vibration was observed by interaction.

The Prediction of Aeroelasticity of F-5 Aircraft's Horizontal Tail with Various Shape of External Stores (외부 장착물 형상에 따른 F-5 항공기 수평미익의 공탄성 특성 예측)

  • Lee, Ki-Du;Lee, Young-Shin;Lee, Dae-Yearl;Kim, In-Woo;Lee, In-Won
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.9
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    • pp.823-831
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    • 2011
  • According to the development of loading equipments, it is usual to change or replace the existing stores. It has been known that pylon-mounted under stores strongly affect aircraft dynamics characteristics due to the change of aerodynamics. To predict the aerodynamics and aero-elasticity is essentially requested with considering the configuration and shape of external stores during the development of aircraft and/or external stores. In this paper, computational fluid dynamics and computational structure dynamics interaction methodology are applied for prediction of aerodynamic characteristics for F-5 aircraft's horizontal tail with various shape of external stores. FLUENT and ABAQUS were used to calculate fluid and structural dynamics. Code-bridge was made base on the globally supported radial basis function to execute interpolation and mapping. As a result, even though the aeroelasticity of the horizontal tail slightly changes according to the shape of external store, the flutter was not occurred at the considered flight conditions in this study.