DEWEK 2004 Lecture by Aero Dynamik Consult GmbH, Dipl. Ing. Stefan Kleinhansl ADCoS – A Nonlinear Aeroelastic Code for the Complete Dynamic Simulation of WEC on Offshore – Structures and Lattice Towers Offshore – Structures and Lattice Towers Aero Dynamik Consult GmbH Dipl. Ing. Stefan Kleinhansl, Dipl. Ing. (FH) Andreas Mangold Dipl. Ing. Michael Mayer

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 2 Contents: Introduction Equations of Motion – Basics of the source code Modelling Examples Available output and post-processing Results Conclusions Aero Dynamik Consult – who we are

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 3 Aerodynamics Aeroelastic computation Design of components Fatigue, strength calculations FEM - calculations Design load assessment, calculation of loads Rotor blade design Controler design Site approvals Aero Dynamik Consult – Engineering Consultancy Service provider related to windenergy with major focus on: Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 4 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Development of Wind Energy Converters (WEC) in the past, and the trend to steadily increasing turbines requires: Most possible accuracy in prediction of the extrem- and fatigue loads under operational conditions Consideration of interaction between the structural movement and aerodynamic loads Since 1996 development of aeroelastic code ADCoS: A eroelastic and D ynamic C omputation o f S tructures

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 5 Dynamic system WEC on lattice tower and offshore structure ADCoS simulation model Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Need to simulate the complete dynamic system WEC using ADCoS aeroelastic simulation software

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 6 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Equations of Motion Basis of the Source Code

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 7 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions The general differential equation of motion of an oscillating system in an arbitrary moving coordinate system is given by: x z

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 8 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions In the aeroelastic code ADCoS the equations of motion are solved with a non-linear implicit integration method in time domain using FINITE – ELEMENT - METHOD. 2 - Node BEAM - element Centrifugal and acceleration stiffness for rotating elements. The mass matrix is consistent, this means the same interpolation functions are used as for displacements. This leads to very accurate results for displacements and bending moments! 6 degrees of freedom per node Cubic displacement interpolation function for bending Linear displacement interpolation function for torsion

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 9 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions The FEM – grid is changed in every time step depending the new state of the WEC (speed, pitch,...) Stiffness - and damping – matrices are updated simultaneously in every time step Non-linear effects (like flapwise deformation for the pitch-moment of the rotorblade) are included Number of considered frequencies only depends on number of used elements (difference to modal analysis) Predeflection of rotorblades easily to model Individual mass properties for each element (i.e. unsymmetrical ice covering)

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 10 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions WEC on lattice tower 567 Elements, 1752 degrees of freedom OWEC with tripod foundation 179 Elements, 1044 degrees of freedom Examples for an ADCoS simulation model

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 11 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Available Output and Post Processing

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 12 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions ADCoS Post Processing: Time series of displace- ments, velocities and accelerations Time series of forces and moments Forces / Moments [kN] / [kNm] Time [s] Displacements [m] / [rad] Time [s]

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 13 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions ADCoS Post Processing: Rainflow counting Fatigue calculations Load spectra Rainflow-Counting Forces N [-] Mean Range Spectra Forces / Moments Range [kN] [kNm] N [-]

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 14 ADCoS Examples of Results Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 15 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Non linear pitch torsional moment caused from flapwise deflection: M i = m * g * dx i Calculation of non-linear pitch torsional dynamics of the rotorblade: Blade 1 flapwise deflection Blade 1 after 180° roundation dx i cg i ROTOR- AXIS dx i cg i M i

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 16 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Calculation of torsional divergence (flutter) Torsional divergence depends on: Position of c g along chord Position of aerodynamic force center Position of shear center (E s ) EsEs cgcg EsEs cgcg For calculations in future: Load reduction due to torsional deflection

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 17 Fast – Fourier – Analysis Fast – Fourier – Analysis e.g.: of a single diagonal of a lattice tower Local bending modes of the regarded element Global tower modes Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 18 Comparision of measured and simulated stress spectra of a corner member of a lattice tower Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Measured by P-E-Concepts, Essen, Germany

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 19 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Simulation of NON-LINEAR FOUNDATION: Nonlinear p-y / M-y curve of a tripod pile of an OWEC caused by an extreme operating gust Nonlinear soil behaviour e.g.: of a tripod foundation on sand or layered soil, can be calculated from commercial software like ALLPILE, L-PILE and added to ADCoS as a NON-LINEAR PILE-ELEMENT

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 20 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Simulation of wave loading : External load (time series of wave loading) ADCoS pre process Time series simulated by WaveLoads* *Institute of Fluid Mechanics, University of Hannover, Germany External load such as wave loads, calculated by WaveLoads software from the GIGAWIND project can be added as time series on offshore structures from OWEC in ADCoS.

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 21 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Simulation of wave loading : Dynamic response in ADCoS Simulation Element 144 External load such as wave loads, calculated by WaveLoads software from the GIGAWIND project can be added as time series on offshore structures from OWEC in ADCoS.

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 22 Conclusions Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 23 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions With aeroelastic code ADCoS a powerful tool for calculat- ing the dynamic response of WEC / OWEC is given! With aeroelastic code ADCoS a powerful tool for calculat- ing the dynamic response of WEC / OWEC is given! Reaction coupling of aerodynamics, structural movement and WEC management is included. Reaction coupling of aerodynamics, structural movement and WEC management is included. All non-linear behaviour of the rotating, accelerating rotor (virtual gyroscopic damping, angular acceleration stiffness) can be calculated.

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 24 Aero Dynamik Consult – who we are Introduction Equations of Motion Modelling Examples Available output and post-processing Results Conclusions Arbitrary tower structures can be modelled and the complete dynamic response of wind energy converters on offshore- structures (tripods, jackets) can be calculated. Arbitrary tower structures can be modelled and the complete dynamic response of wind energy converters on offshore- structures (tripods, jackets) can be calculated. Load calculations of ADCoS validated by German Lloyd, TÜV Nord, RW-TÜV for various WEC up to 5MW-Class Load calculations of ADCoS validated by German Lloyd, TÜV Nord, RW-TÜV for various WEC up to 5MW-Class

ADCoS - A Nonlinear Aeroelastic Code for Complete Dynamic Simulation of WEC Aero Dynamik Consult GmbH 25 Thank you very much for listening to our presentation