wind turbine-overall dynamics (coupling of structure, wind and waves)


Stuttgart Wind Energy (SWE) at the Institute of Aircraft Design


Contact Person:

Dr.-Ing. Anne Jüngert


Load Simulation


There are numerous possibilities at the Stuttgart Chair of Wind Energy (SWE) of the University of Stuttgart to simulate loads on onshore and offshore wind turbines. Depending on the purpose, models at different complexities can be coupled and support investigations. The spectrum goes from reduced models for longer simulated times to detailed models of drive trains, of support structures or rotor blades with CFD for the aerodynamics.


Overview Simulation software:


  • Flex5
  • Bladed
  • FAST
  • FE Software: ANSYS, ABAQUS, Poseidon
  • MKS Software: SIMPACK
  • CFD Code: FLOWer



Modal Approach: Flex5+FE, Bladed, FAST


Simulations using model reduction techniques and partially coupled finite element models produce accurate models for preliminary design with a very short processing time. The models are able to accurately represent the critical components from the foundation to the rotor blades. The models can have turbulent wind inputs along with wave loading for offshore models.



Multibody Systems (MBS): SIMPACK, Bladed (MBS)


Multibody simulation software (MBS) allows for high level simulations of wind turbine models. MBS model building is particularly flexible. It is possible to represent flexible components by integrating modal-reduced FE-bodies (Flexible Multibody Systems FMBS).  Geartooth contacts, bearing stiffness (in the drive train or pitch system), mooring system (floating turbines) and any flexible bodies can be modeled. The Endowed Chair of Wind Energy (SWE) uses both Bladed from GL/Garrad Hassan and SIMPACK. The SWE has cooperated for many years with the two software companies and takes part in the development of the SIMPACK module serving the design of Wind Turbines.



Fluid structure coupling with CFD: FLOWer -SIMPACK


Along with the basic aerodynamic theories, such as the Blade Element Momentum (BEM)  theory or  the Free Vortex theory, the Flow solver FLOWer is coupled with the MBS program SIMPACK for very detailed simulations of aeroelastic issues. The involved institutes possess a powerful software package for “Aeroelastic Multibody Simulation” with which the structural dynamics can be modeled with a very high level of detail thanks to the MBS. The aerodynamics can be solved without the BEM theory but by using the URANS method (implemented in the FLOWer code). The MBS models coupled with this tool permit an analysis of  both the structural loads and the aerodynamics (the pressure distribution on the blade surface and overall flow field).


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System Identification, Condition Analysis, Model Updating:


  • System Identification:
    • Identification of the state of mechanical structures in plant and mechanical engineer-ing using classical modal analysis and operational modal analysis (OMA)
    • Measurement of the system response with seismic sensors (cyclic speed readers) and piezoelectric acceleration sensors
    • Determination of deformation using strain gauge and optical measuring techniques
    • Stress analysis with LMS Test. Lab Structures
  • State Analysis: Calculation of the eigenfrequencies and eigenforms of mechanical structures in plant and mechanical engineering using the finite element program Abaqus FEA
  • Model Updating: adaption of unknown model system parameters – for example, boundary and transition conditions and restraint intensity – to the results of experimental model analy-sis using the finite element program FEMtools from Dynamic Design Solutions (DDS). With this, stiffness values from i.e. non-reachable locations such as offshore plants can be determined.



Dampening of Vibrations


Qualification of tuned massed dampers in cooperation with the manufacturer is important in order to decrease the amount of undesired highly structure-dynamical stresses on mechani-cal systems such as tower vibrations.




Mode 1 and Mode 2 of a wind energy plant Illustration: MPA Stuttgart