M. Kohlmeier 1, T. Kossel 2, B. Reil 1, and R. Rolfes 1

Transcription

1 IEA Annex XXIII Offshore Code Comparison Collaborative (OC3) Phase IV OC3-Hywind Multibody Simulation of the Support Structure Dynamics of Floating Wind Turbines M. Kohlmeier 1, T. Kossel 2, B. Reil 1, and R. Rolfes 1 ForWind Center for Wind Energy Research RAVE GIGAWIND alpha ventus Leibniz Universität Hannover 1) Institute for Structural Analysis 2) Institute of Fluid Mechanics 11 th Full Committee Meeting, KTH-Mechanics Facilities, Sweden Stockholm, Sept. 17, 2009

2 Contents Motivation Integrated Modelling of Floating OWECs Simulation Approach for Multibody Modelling Current Status of OC3-Hywind Spar-buoy Modelling Preliminary Results of Load Case Simulations 2

3 Motivation Interactions Turbulent wind fields and their aeroelastic interaction with the rotor dynamics Impacts Design wave Stochastic simulation H, T Integrated Modelling Time domain analysis of the support structure including wind and wave loads Fast and reliable methods - simplified vs. complex approaches - individual optimization Flexibility according to chosen type of support structure Tailored sequence H, T H s, T p H s, T p Commercial and internal codes - Ansys, MD Adams, MD Nastran etc. - Fast/AeroDyn, WaveLoads - Poseidon/Flex5, aeroflex etc. 3

4 Pre-processing for FE and Multi-body Simulations using WaveLoads 2.0 WaveLoads Pre-processor Finite Element Modelling ANSYS MD Nastran Abaqus Multibody Dynamics MD Adams 4

5 Multibody Dynamics Simulation in MD Adams for OC3-Phase III Assembly Step: Wind Turbine Tripod Support Structure + OC3-Tripod 1.5 MW NREL-Turbine Turbine on OC3-Tripod simulated in MD Adams 5

6 OC3-Phase IV Recent Developments: Wave loading and buoyancy force calculation on moving sub structures Multi-budy simulations provide displacements, velocity and acceleration of the members Incorporation of mooring system (3 rd option: single mooring line data) Direct coupling applied in Adams 5-MW Reference Wind Turbine OC3-Hywind Spar-buoy 6

7 OC3-Phase IV Dynamics of Slender Floating Structures Plausibility Check Wave loading due to Morison approach and buoyancy forces on moving structures Incorporation of the relative motion and acceleration of the structure provided in a multi-body simulation framework (Adams) Prediction of hydrodynamic damping due to fluid structure interaction 7

8 Modules for Multibody Simulation in MD Adams Model Set-up FAST Aeroelastic Design Code for Horizontal Axis Wind Turbines (NREL, Jason Jonkman) Controller for torque and blade-pitch Interaction with the Wind Field AeroDyn aerodynamics software library (NREL, David J. Laino) TurbSim A stochastic, full-field, turbulent-wind simulator for use with the AeroDyn-based design codes (YawDyn, FAST, and MSC.ADAMS ) (NREL, Neil Kelley and Bonnie Jonkman) Impact of the Waves / Buoyancy WaveLoads Wave loads resulting from the current sea state acting on the support structure supposed to be hydrodynamically transparent (LUH, Kim Mittendorf, Nguyen Ba, Martin Kohlmeier) Mooring System MooringLines Mooring Line Forces from Data File in WAMIT Format Fortran 90, DLL Fortran 90, DLL Fortran 90, DLL Fortran 90 (NREL - National Renewable Energy Laboratory) C++, DLL C++, DLL Foundation Soil Model Supply of material data for linear and nonlinear soil modelling DLL 8

9 Overview of Source Code used in MD Adams Model Creation of Adams.dll for linking with MD Adams FAST Fortran 90 AeroDyn Fortran 90 Adams2AeroDyn Fortran 90 Adams.obj Controller.obj Adams2WaveLoads C WaveLoads C++ Adams2MooringLine C MooringLine C++ Adams.obj Adams.dll Controller.dll Adams2WaveLoads.dll WaveLoads.dll Adams2MooringLine.dll MooringLine.dll Remark: MD Adams R3 may use multiple DLL files. 9

10 OC3-Phase IV Load Case 1.4 Decay Test in Surge Considerable damping in surge Remarks Additional load applied at fairleads for compensation of the missing wind turbine Additional damping values in surge, sway, heave and roll are not applied C D = 1.0, C DM =

11 OC3-Phase IV Load Case 4.1 Regular Wave Airy, H=6m, T=10s Remarks Additional load applied at fairleads for compensation of the missing wind turbine Additional damping values in surge, sway, heave and roll are not applied C D = 1.0, C M =

12 Pitch Failure Test Case of WindPACT 1.5 MW Baseline FAST Certification Test #11: Wind turbine undergoing a pitch failure CD = 1.0, CM = 2.0 Airy, H=6m, T=10s 12

13 Current Model Wind Loads - Blade Element Momentum Method [AeroDyn] Structural Response - Finite Element Simulation [ANSYS, MD Nastran, Abaqus] - Multibody Dynamics [MD Adams] Wave Loading - Regular or Irregular Waves -SeaSates [WaveLoads] Mooring System - Single Mooring Line Properties [MooringLine] Conclusion Consideration of damping in yaw and heave could be more realistic: dynamic analysis of the mooring lines including the consideration of hydrodynamic forces acting on the mooring lines might be necessary Next Steps Export results for all output parameters 13

14 Thank you for your attention. 14