Multi-flexible-body Dynamic Analysis of Horizontal Axis Wind Turbines

Authors

  • Donghoon Lee,

    1. School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0150, USA
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  • Dewey H. Hodges,

    Corresponding author
    1. School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0150, USA
    • School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0150, USA.
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  • Mayuresh J. Patil

    1. School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0150, USA
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    • Department of Mechanical Engineering, Widener University, Chester, Pennsylvania.


Abstract

This article presents a structural dynamic analysis of horizontal axis wind turbines (HAWTs) using a new methodology. The methodology is based on representing a HAWT as a multi-flexible-body system with both rigid- and flexible-body subsystems. The rigid-body subsystems (nacelle, hub) are modelled as interconnected sets of rigid bodies using Kane's method. Kane's method leads to compact equations of motion for rigid-body mechanisms. The flexible-body subsystems (blades, tower) are modelled using geometrically exact, non-linear beam finite elements derived from a mixed variational formulation for the dynamics of moving beams. The use of the mixed formulation allows for the direct determination of constraint forces and moments within the beam finite element and at the boundaries, thus allowing simple connectivity between the finite elements and rigid bodies. The equations for the rigid and flexible subsystems are coupled to obtain a unified framework that models the dynamic behaviour of the complete system. Linearization of the dynamic equations about the steady state solution yields system equations with periodic coefficients that must be solved by Floquet theory to extract the dynamic characteristics. Numerical studies are presented to investigate the natural frequencies and mode shapes for a HAWT with flexible blades and tower. Copyright © 2002 John Wiley & Sons, Ltd.

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