2006 Wind Program Peer Review Design Codes Jason Jonkman Sandy Butterfield Marshall Buhl Gunjit Bir Pat Moriarty Alan Wright Neil Kelly Bonnie Jonkman 2006 Wind Program Peer Review May 10, 2006

Outline of Presentation Introduction & Background State of the Art Modeling & Limitations Program Contributions Current & Future Work

Introduction & Background The Big Picture

Introduction & Background Modeling Requirements Fully coupled aero-hydro-servo-elastic interaction Wind-Inflow: discrete events turbulence Waves: regular irregular Aerodynamics: induction rotational augmentation skewed wake dynamic stall Hydrodynamics: scattering radiation hydrostatics Structural dynamics: gravity / inertia elasticity foundations/moorings Control system: yaw, torque, pitch

State of the Art Modeling & Limitations Wind-Inflow Rotor Performance: steady/uniform Design: IEC-specified deterministic, discrete inflows and an idealistic neutral turbulence simulation (supported by TurbSim) Research: TurbSim now provides a variety of specific operating environments including flows over flat, homogenous terrain, in and near multi-row wind farms, the NWTC Test Site (complex terrain), and the Great Plains with and without the presence of a low- level jet stream

State of the Art Modeling & Limitations Wind-Inflow (cont) Current Limitations The Great Plains simulation provides low-level jet wind speed and direction profiles up to 490 m but the turbulence scaling has been extrapolated with validated data from 120 to 230 m (the top of a future 10MW turbine rotor). Data is needed within this height range for validation. The wind farm simulations are only based on validated data up to a height of 50 m, data is needed to expand and validate this capability for modern wind farms consisting of multi-megawatt turbines for both onshore and offshore installations. Detailed turbulence measurements and updated models are needed for a range of climatic types in order to better assess potential operating environments and aid in improving siting and turbine reliability.

State of the Art Modeling & Limitations Aerodynamics & Aeroacoustics THIS SLIDE TO BE EDITED BY PAT Rotor Performance: BEM (WT_Perf) Design: GDW, interaction with elasticity (AeroPrep, AeroDyn) Research: Vortex, CFD Current Limitations: mention what can and cannot be done corrections for: rotational augmentation, dynamic stall, unsteady wake, etc.

State of the Art Modeling & Limitations Aerodynamics & Aeroacoustics (cont) THIS SLIDE TO BE EDITED BY PAT

State of the Art Modeling & Limitations Offshore Waves & Hydrodynamics Fixed-Bottom Design: Linear & nonlinear waves + Morison Floating Design: Linear wave + potential flow (floating) Research: CFD Current Limitations: mention what can and cannot be done no steep/breaking waves no 2nd order slow-drift/sum-frequency effects no sea current/VIV no sea ice

State of the Art Modeling & Limitations Offshore Waves & Hydrodynamics

State of the Art Modeling & Limitations Structural Dynamics Design: external geometrymaterial lay-ups Loads Analysis: Modal (PreComp, BModes, FAST) Research: Multibody, FEM (ADAMS, RCAS) Furling - DWT Current Limitations: mention what can and cannot be done No coupled modes No flap/twist coupling No precurve/presweep

State of the Art Modeling & Limitations Structural Dynamics (cont)

Program Contributions Users & Certification

Program Contributions Why Develop Design Codes In-House? Other codes: Bladed, FLEX5, DHAT, Phatas, HAWC2 Flexibility: custom design for our unique requirements Full system Vs. Component level Support U.S. wind industry: workshops

Current & Future Work Wind-Inflow Current work: Document the development of TurbSim Use the TurbSim Great Plains Low-Level Jet Spectral Model to excite the 5MW Reference Turbine to assess and document the effects of these jets on LWST turbines Analyze the available Lamar LIDAR data to obtain further validating information of Great Plains LLJ spectral model simulations Planning for a workshop on inflow turbulence issues and training in the use of TurbSim Future plans (2 years out): Plan field experiment to collect data on turbulence within large, multi-megawatt wind farms Future opportunities: Form a multi-discipline, synergistic effort to understand the role of coherent inflow turbulence on turbine drive train dynamics and fatigue

Current & Future Work Aerodynamics & Aeroacoustics THIS SLIDE TO BE EDITED BY PAT Current work: improved fidelity of GDW tower influence Future plans (2 years out): Rewrite AeroDyn – make modular, provide hooks for other aero models Future Opportunities: Wind tunnel tests/NASA Ames data: improve engineering aero modules Aerodynamics: add vortex aero module Add CFD aero modules

Current & Future Work Offshore Waves & Hydrodynamics Current work: Fixed-bottom Offshore foundations: p-y, t-z Floating: WAMIT Mooring dynamics: Lines OC3 benchmarking Future plans (2 years out): ??? Future opportunities: breaking waves 2nd order potential flow

Current & Future Work Structural Dynamics

Current & Future Work New Horizons Gearbox dynamics: Gearbox housing deflection? Missing internal gearbox loads? Tower shadow Controls/stability analysis Code validation FEM

Introduction & Background What are Design Codes Used For? R&D knowledge feeds into codes: Aero Hydro Controls Etc. ---------------- Preliminary design: Rotor performance Material lay-ups Detailed design: Loads Certification Controller design (see Alan’s presentation) Research: new concepts Benchmarking Designers are limited by code capability

Introduction & Background Design / Certification Process Explain how codes fit into the design/certification process Preliminary design Detailed design research Load cases Quantity type (extreme, fatigue) Justify need for engineering models, as opposed to straight-up CFD/FEM

Current & Future Work Structural Dynamics

Current & Future Work Structural Dynamics

Current & Future Work Structural Dynamics

Outline of Presentation Introduction & Background Model Development Sample Results Conclusions Future Work Acknowledgements

Introduction & Background The Big Picture Some wind turbines have been installed in shallow water; none in deepwater A vast deepwater offshore wind resource represents a potential to power much of the world using floating wind turbines Numerous platform concepts are possible Simulation tools capable of modeling the dynamic responses are needed GE Wind Energy 3.6 MW Turbine

Introduction & Background Modeling Requirements for Floating Turbines Turbulent winds Irregular waves Gravity / inertia Aerodynamics: induction skewed wake dynamic stall Hydrodynamics: scattering radiation hydrostatics Elasticity Mooring dynamics Control system Fully coupled

Model Development Onshore Wind Turbine Simulators FAST Fatigue, Aerodynamics, Structures, and Turbulence Developed by NREL/NWTC Originated from Oregon State University Wind turbine specific (HAWT) Structural dynamics and controls Combined modal & multibody rep. (modal for blades and tower) Up to 24 structural DOFs Preprocessor for MSC.ADAMS MSC.ADAMS® Automatic Dynamic Analysis of Mechanical Systems Commercial (MSC.Software Corporation) General purpose Structural dynamics and controls Multibody dynamics representation Virtually unlimited structural DOFs Datasets created by FAST Both use AeroDyn aerodynamics Equilibrium inflow or generalized dynamic wake Steady or unsteady aerodynamics Aeroelastic interaction with structural DOFs

Model Development Offshore O&G Platform Simulators Hydrodynamic simulators for offshore platforms developed by the Center for Ocean Engineering, Massachusetts Institute of Technology (MIT) SML Developed for Offshore Platforms SML SWIM – treatment of linear and second-order frequency-domain hydrodynamics MOTION – solutions of the large-amplitude time-domain slow-drift responses LINES – determines the nonlinear mooring-line / tether / riser effects upon the platform Wave Analysis @ MIT (WAMIT) solves wave interaction problem using numerical panel method

Model Development Coupling Hydrodynamics with Aeroelastics FAST and the ADAMS processor upgraded to add: support platform DOFs platform loading SML and WAMIT used where applicable Add hydrodynamic loading and mooring system dynamics here Add support platform kinematics & kinetics here

Model Development Support Platform Kinematics & Kinetics Introduce support platform DOFs to FAST and the ADAMS preprocessor: translational: surge, sway, heave rotational: roll, pitch, yaw (assume small rotations) Include dynamic couplings between motions of platform and turbine: all position, velocity, and acceleration expressions are now affected by the platform DOFs the wind turbine’s response to wind and wave excitation is fully coupled through the structural dynamics Support Platform DOFs

Model Development Support Platform Kinematics & Kinetics (cont) The equations of motion (EoMs) in FAST are derived and implemented using Kane’s Dynamics: complete, nonlinear aeroelastic EoM: Total external load on the support platform: hydrodynamic added mass important since ρwater ≈ ρstructure (aerodynamic added mass not important since ρair « ρstructure) to avoid making the EoM implicit, separate out the added mass components from the rest of the load: + +

Model Development Hydrodynamic Loading—Possible Realizations Advantages Disadvantages Application Linear Frequency Domain Many codes available from offshore O&G industry Results presented in summary form (RAOs or statistics) Rigid payload No nonlinear dynamic characteristics No transient events Morison’s Equation Time Domain Easy to implement Easy to incorporate nonlinear / breaking waves Diffraction term only valid for slender base No wave radiation or free surface memory No added mass-induced coupling between modes True Linear Time Domain Satisfy linearized governing BVPs exactly, without restriction on platform size, shape, or manner of motion Frequency domain solution used as input Linear waves only No 2nd order effects

Model Development Hydrodynamic Loading (cont)—Assumptions Assume – Potential Flow: incompressible and inviscid fluid irrotational flow subject only to conservative body forces Assume – Linearization of Hydrodynamics Problem: wave amplitudes are much smaller than wavelengths translational motions of platform are small relative to its size application of superposition Limitations: no nonlinear wave kinematics no 2nd order slow-drift excitation no 2nd order sum-frequency effect no sea current or vortex-induced vibrations (VIVs) ignore potential loading from floating debris or sea ice

Model Development Hydrodynamic Loading (cont)—Overview Aij and fi must be defined in: Problem is split into separate and simpler problems: Scattering: seek loads on platform when it is fixed and incident waves are present Froude-Kriloff, diffraction Hydrostatics: seek loads on platform when it is in equilibrium and there are no waves present buoyancy Radiation: seek loads on platform when it oscillates in its various modes of motion with no incident waves present, but waves radiate away added mass, radiation damping

Model Development Hydrodynamic Loading (cont)—Scattering Wave excitation: Wave elevation: = FFT of White Gaussian Noise = wave spectrum = complex wave excitation force per unit wave amplitude, depending on: geometric shape of platform frequency and direction of incident wave proximity to seabed, free surface, etc. sea current / forward speed solution to the frequency domain problem Wind and Wave Spectra White Guassian Noise

Model Development Hydrodynamic Loading (cont)—Hydrostatics = static buoyancy from Archimede’s Principle: generally cancels with the weight of the floating body and the weight in water of the mooring lines; separated out due to turbine flexibility = change in hydrostatic load from the effects of: waterplane area changes in displaced volume center-of-buoyancy vector cross product moments

Model Development Hydrodynamic Loading (cont)—Radiation Aij and = impulsive added mass and radiation kernel, determined from solution to frequency domain problem: and = added mass and damping, depending on: geometric shape of platform proximity to seabed, free surface, etc. Wave radiation damping loads exhibit memory effects, meaning they depend on the history of platform motion: = ith component of load at t due to unit impulse in speed of DOF j and or frequency of oscillation sea current / forward speed

Model Development Mooring System Dynamics A mooring system restrains a support platform with cable tension, depending on: excess buoyancy of platform platform location / motion cable weight in water hydrodynamic loading seabed friction geometrical layout of cables If the mooring compliance was linear: Mooring dynamics introduced in FAST and ADAMS by interfacing with LINES module: ignores effects of bending stiffness Oil Rig TLP

Model Development Calculation Procedure Summary

Sample Results Baseline Wind Turbine & Platform Properties NREL baseline 5MW rating 126m diameter 90m hub height 700,000kg mass Wave Excitation in X-Direction Platform: MIT design TLP 19m diameter 17m draft 134,000kg mass Baseline Wind Turbine with TLP Added Mass and Damping in Surge Radiation Kernel in Surge

Sample Results MSC.ADAMS Simulation

Sample Results FAST & ADAMS Verification

Sample Results MSC.ADAMS Simulation

Conclusions Developed simulation tools capable of modeling a variety of floating wind turbines: started with FAST and ADAMS preprocessor added support platform DOFs: surge, sway, heave roll, pitch, yaw added hydrodynamic loading: scattering hydrostatics radiation added mooring system dynamics (Lines) Established critical capability to help the US wind industry evaluate design options for deepwater wind development use SML or WAMIT as preprocessor

Future Work Using simulation capability: New model development: characterize dynamic response and identify critical loads and instabilities assess the role of wind turbine control to provide platform stability and loads mitigation New model development: 2nd order effects sea current and VIVs loading from sea ice fixed-bottom support bases and breaking waves blade torsion DOF and coupled modes Model validation and refinement

Acknowledgements Walt Musial & Sandy Butterfield of NREL for leading US offshore wind research program Erik Withee of US Navy for initiating study at MIT Kwang Lee of MIT for verifying output of SWIM Libby Wayman of MIT for modifying SWIM My Ph.D. Committee at CU, UW, NREL, & MIT for evaluating the project

Introduction & Background Contrasting Modeling Requirements Offshore Oil & Gas Platforms Rigid and static Steady winds in analysis Linear frequency domain analysis Passive Offshore Fixed-Bottom Turbines Rigid support structure Little coupling between turbine and support structure motions Separation of dynamic response and wave spectra Shallow water / breaking waves Onshore Wind Turbines Flexible and dynamically active Turbulent winds in analysis Nonlinear time domain analysis Controllable Offshore Floating Wind Turbines Compliant support structure Significant coupling between turbine and platform motions Response and wave spectra coalescence Deepwater / linear waves

Model Development Hydrodynamic Loading—Assumptions Assume – Potential Flow: incompressible and inviscid fluid; irrotational flow subject only to conservative body forces Assume – Linearization of Hydrodynamics Problem: wave amplitudes are much smaller than wavelengths translational motions of platform are small relative to its size application of superposition problem is split into 3 separate and simpler problems: (scattering, hydrostatics, radiation) Limitations: no nonlinear wave kinematics no 2nd order slow-drift excitation no 2nd order sum-frequency effect no sea current or vortex-induced vibrations ignore potential loading from floating debris or sea ice

Model Development Hydrodynamic Loading—Scattering Scattering: seek loads on platform when it is fixed and incident waves are present Found by IFFT of the product of wave spectrum, normalized complex wave excitation force, and FFT of White Gaussian Noise Froude-Kriloff, diffraction loads depend on: amplitude, frequency, direction of incident waves geometric shape of platform proximity to seabed, free surface, etc. sea current / forward speed solution to frequency domain problem Wind and Wave Spectra

Model Development Hydrodynamic Loading—Hydrostatics Hydrostatics: seek loads on platform when it is in equilibrium and there are no waves present Found by summing static buoyancy and its change with platform displacement Buoyancy load depends on: waterplane area loacation of center-of-buoyancy

Model Development Hydrodynamic Loading—Radiation Radiation: seek loads on platform when it oscillates in its various modes of motion with no incident waves present, but waves radiate away Found by convolution of platform velocity and radiation kernel Radiation kernel found by sin- or cosine-transform of added mass or damping matrices Added mass, radiation damping loads depend on: history of platform motion (memory effect) geometric shape of platform proximity to seabed, free surface, etc. sea current / forward speed solution to frequency domain problem

Model Development Mooring System Dynamics Oil Rig TLP A mooring system restrains a support platform with cable tension, depending on: excess buoyancy of platform platform location / motion cable weight in water hydrodynamic loading seabed friction geometrical layout of cables Mooring dynamics introduced in FAST and ADAMS by interfacing with LINES module: ignores effects of bending stiffness

Model Development Calculation Procedure Summary MODIFY THIS TO INDICATE WHERE SWIM/WAMIT and LINES ARE!!!

Introduction and Background Previous Studies—Fixed-Bottom Several wind turbine simulators have been expanded to model fixed-bottom offshore support structures: use linear wave theory for irregular sea and nonlinear Stream Function theory for regular sea wave kinematics use Morison’s equation for hydrodynamic loading: Fixed-Bottom Offshore Turbine DUWECS

Introduction and Background Previous Studies (cont)—Floating A few simulators have been developed for the preliminary analysis of floating support structures: frequency domain: Bulder et al — found RAOs and amplitude standard deviations of the 6 rigid body modes for a tri floater design Lee — performed similar analysis for TLP and Spar Buoy designs Results — natural frequencies of platform can be designed away from peak of wave spectrum time domain: Henderson — used RAOs to prescribe platform motion in state domain Withee — hydrodynamic loading via Morison’s eq. for a TLP Fultan et al — hydrodynamic loading via Morison’s eq. for a TLP Results — platform motions have little effect on power performance and rotor loads, but a large effect on nacelle and tower loads Response Amplitude Operator (RAO)

Introduction and Background Previous Studies (cont)—Onshore Controls Disturbance Accommodating Control (DAC) has been used to design multiple-input, multiple-output (MIMO) controllers to mitigate loads and stabilize flexible modes of onshore wind turbines References: Stol and Balas Hand and Balas Wright and Balas Disturbance Generator Plant Generator Torque Nacelle Yaw Blade Pitch Control Actions Plant State Estimator Composite Estimator Disturbance Estimator

Thesis Statement and Objectives Limitations of Previous Studies Developed dynamics models are limited in capability: do not permit multiple platform and mooring configurations frequency domain models ignore turbine flexibility, nonlinear dynamic characteristics, and transient events time domain models ignore the effects of: platform size in the diffraction problem wave radiation damping and free surface memory added mass-induced coupling between modes of motion Load results are demonstrated through few simulations: must be verified through a rigorous loads analysis No attempt to mitigate the increased loads through the application of simple or advanced control theory

Thesis Statement and Objectives Goals of Work To develop simulation tools capable of modeling the fully coupled aeroelastic and hydrodynamic responses of a variety of floating offshore wind turbines To identify critical loads and/or instabilities that are brought about by the dynamic couplings between and within the turbine and platform in the presence of combined wind and wave loading To design, simulate, and assess the effectiveness of an advanced controller to mitigate unwanted loads and/or instabilities using generator torque, blade pitch, and/or nacelle yaw

Approach and Methods Design Loads Analysis Involves verifying structural integrity by running a series of design load cases (DLCs) IEC 61400-1 for onshore or IEC 61400-3 for offshore Load Case Matrix Critical Locations

Approach and Methods Design Loads Analysis (cont) Using FAST, I will compare load case simulation results between the onshore and offshore configurations: use NREL’s baseline wind turbine and reference site pick one candidate support platform concept and subset of DLCs Identify critical loads and/or instabilities brought about by the dynamic couplings and combined wind and wave loading Q: Is power performance degraded? Q: Where and by how much are loads increased? Q: What are the dominant instabilities?

Approach and Methods Controls Design I will use DAC to design MIMO state-space controllers to mitigate detrimental loads and/or instabilities: pick one or two of the critical loads and/or instabilities extend linearization capability of FAST to include states and disturbances associated with platform motion and wave loading implement and test controller in FAST/Simulink interface Q: Can independent pitch, torque, or yaw be used to control combinations of wind and wave loading? including side-to-side loading? Q: Are actuators other than pitch, torque, and yaw required for controllability? Q: What measurements are needed for observability? blade root & shaft strain gages, nacelle accelerations, etc.?

Approach and Methods Project Scope As I get deeper in depth, I narrow my focus

Recent Progress Support Platform Kinematics & Kinetics Add support platform kinematics & kinetics here

Recent Progress Support Platform Kinematics & Kinetics (cont) Assume small rotations: rotation order doesn’t matter use linearized Euler transformation: Orthogonal Rotations 1 X Y Z x y z Not an orthonormal transformation :. use a correction The closest orthonormal matrix in the Frobenius norm sense is [U][V]T where [U] and [V] are the matrices of eigenvectors inherent in the Singular Value Decomposition (SVD) of the matrix

Recent Progress Hydrodynamic Loading Add hydrodynamic loading and mooring system dynamics here

Work Plan Review Background Literature September 2005 Learn fundamentals of marine hydrodynamics Identify computational methodologies used by other simulation tools developed for offshore wind turbines Examine requirements for determining design loads Learn about design process for advanced controls Develop Simulator December 2005 Add support platform DOFs to FAST Develop a support platform hydrodynamics loading model and interface it to FAST and ADAMS Interface LINES module to FAST and ADAMS Verify response predictions between FAST and ADAMS and frequency domain results Publish AIAA paper on model development activities

Work Plan (cont) Establish Baseline Turbine & Site February 2006 Identify baseline turbine rating and reference site location Establish aerodynamic and structural properties Define a baseline control system Create FAST and ADAMS models Identify and design candidate support platform concepts Establish a design basis at the reference offshore site Perform Design Loads Analysis October 2006 Pick one of the candidate support platform concepts for subsequent analysis Identify a subset of DLCs to run Run DLCs to determine on- and offshore design loads Compare results to identify critical loads and/or instabilities Publish conference paper on modeling results

Work Plan (cont) Controls Design March 2007 Pick one or two critical loads and/or instabilities for subsequent analysis Design an advanced torque, pitch, and/or yaw controller to mitigate the unwanted loads and/or instabilities Implement and simulate the controller in FAST Assess the effectiveness of the controller Complete Requirements of Ph.D. May 2007

Thesis Contributions Develop simulation tools capable of modeling a variety of floating offshore wind turbines Characterize the dynamic response and identify critical loads and instabilities Assess the role of wind turbine control to provide platform stability and loads mitigation Establish a critical capability to help the US wind industry evaluate design options for deepwater wind development

Introduction and Background Wind Turbine Fundamentals Wind Speed Power 1 2 3 Rated Cut-In Cut-Out Generator Torque Nacelle Yaw Blade Pitch Control Actions

Introduction and Background Why Offshore? GE Wind Energy 3.6 MW Turbine Higher-quality wind resource: less turbulence, smaller shear stronger, more consistent winds Economies of scale: avoid logistical constraints on size Proximity to loads: many demand centers near coastline Increased transmission options: access to less heavily loaded lines Potential for reducing land use, noise, and aesthetic concerns

Introduction and Background Why Floating?

Model Development Hydrodynamic Loading—Possible Realizations Frequency Domain Representation find Response Amplitude Operators (RAOs) ignore turbine flexibility ignore nonlinear dynamic characteristics ignore transient events Morison’s Representation valid for slender, vertical, surface-piercing cylinders Easily incorporate nonlinear and breaking waves ignore effects of platform size in diffraction problem ignore wave radiation damping and free surface memory ignore added mass-induced coupling between modes of motion True Linear Hydrodynamic Representation in the Time Domain: satisfy the linearized governing BVPs exactly without restriction on platform size, shape, or manner of motion Response Amplitude Operator (RAO)

Thesis Statement and Objectives Limitations of Previous Studies Developed dynamics models are limited in capability: do not permit multiple platform and mooring configurations  important to have for configuration trade-off studies the frequency domain models ignore turbine flexibility, nonlinear dynamic characteristics, and transient events  important considerations for wind turbines the time domain models ignore the effects of: platform size in the diffraction problem  important for large platforms wave radiation damping and free surface memory  important for platforms with compliance added mass-induced coupling between modes of motion  important for platforms that are not axisymmetric Load results are demonstrated through few simulations: must be verified through a rigorous loads analysis  important to characterize the dynamic response and identify design-driving loads No attempt to mitigate the increased loads through the application of simple or advanced control theory  important to minimize cost

Thesis Statement and Objectives Hypothesis Existing aeroelastic models can be expanded to include the important loading and responses representative of floating offshore wind turbines and will demonstrate that the increased dynamic complexity produces detrimental loads and/or instabilities, which can then be mitigated through the development of advanced controls This work is critical to determining the most technically attractive and economically feasible floating wind turbine design

Codes for Component and Full System Level Analysis Determine loads throughout full system for component level analysis Multi-physics model Industry-specific Developed for particular application (FAST, etc.) Component Level Determine design integrity of individual components based on specified loads Single-physics model Not industry-specific Commercial products available (ANSYS, etc.)

Model Fidelity for Multi-Physics Simulation Tools

Approach and Methods Development of a Coupled Simulator (cont) 24 degrees of freedom (DOFs) available for 3-bladed, 22 DOFs available for 2-bladed turbine: blade flexibility: 2 flap and 1 edge mode DOF per blade tower flexibility: 2 fore-aft and 2 side-to-side mode DOFs drivetrain: 1 variable generator speed DOF and 1 shaft torsion DOF nacelle yaw: 1 yaw hinge DOF rotor teeter: 1 rotor teeter hinge DOF with optional 3 (for 2-bladed rotor only) rotor-furl: 1 furl hinge DOF of arbitrary orientation and location between the nacelle and rotor tail-furl: 1 furl hinge DOF of arbitrary orientation and location between the nacelle and tail platform: 3 translation (surge, sway, and heave) and 3 rotation (roll, pitch, and yaw) DOFs 1st mode 2nd mode Modal Representation

Users and Certification

FAST, ADAMS & AeroDyn Interaction

Recent Progress Support Platform Kinematics & Kinetics (cont) The equations of motion (EoMs) in FAST are derived and implemented using Kane’s Dynamics Kane’s EoM for holonomic system: Generalized active forces: Generalized inertia forces: Partial angular velocities: = # of rigid bodies = rigid body i = mass center of rigid body i Partial linear velocities:

Platform Concepts: Analysis Capabilities  X Tension Leg Platform (TLP) Taut Leg Spar Buoy Wind Turbine On Boat Monopile Disk Buoy with Catenary Moorings Tripod Lattice Tri Floater

Future Offshore Code Development Direction Modeling of fixed bottom support structures monopiles multiple-member support structure P-y foundations shallow water (breaking) waves 2nd order mean (wave drift), difference-frequency (slow drift), and sum-frequency wave loading Sea current / forward speed effects Model validation and refinement