jason jonkmansandy butterfieldneil kelley marshall buhlgunjit birbonnie jonkman pat moriartyalan...

Jason JonkmanJason Jonkman Sandy ButterfieldSandy Butterfield Neil KelleyNeil Kelley

Marshall BuhlMarshall Buhl Gunjit BirGunjit Bir Bonnie Bonnie JonkmanJonkman

Pat MoriartyPat Moriarty Alan WrightAlan Wright Daniel LairdDaniel Laird

2006 Wind Program Peer Review2006 Wind Program Peer Review

May 10, 2006May 10, 2006

Design CodesDesign Codes

http://www.sandia.gov/index.html

22006 Wind Program Peer Review

Outline of Presentation

Introduction & Background

State of the Art Modeling & Limitations

Program Contributions

Current & Future Work


Introduction & BackgroundThe Big Picture

Knowledge AreasWind-Inflow

Waves

Aerodynamics

Aeroacoustics

Hydrodynamics

Elasticity

Controls

Power Generation

Design Standards

wind energy knowledge istransferred to the industry

through design codes

Application AreasConceptual Design

Rotor Performance

Turbine Design

Controller Design

Loads Analysis

Certification

Training

Testing Support

Benchmarking

the advancement of windenergy technology is limited

by design code capability

Design Codes


Introduction & BackgroundDesign Loads Analysis

Design requirements are dictated by IEC standards

100s-1000s of design load case (DLC) simulations must be considered

Design Situation DLC Wind Condition

Wave Condition

Directionality Other Conditions

Type of Analysis

Power production 1.x

Power production plus occurrence of fault

2.x

Start up 3.x

Normal shut down 4.x

Emergency shut down 5.x

Parked 6.x

Parked with fault 7.x

Transport, assembly, and maintenance

8.x

Load Case MatrixCritical Locations


Introduction & BackgroundModeling 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


Introduction & BackgroundCoupled Aero-Hydro-Servo-Elastic Simulation

AeroDynTurbSim

HydroDyn

FAST &ADAMS

Wind TurbineAppliedLoads

ExternalConditions

Soil

Hydro-dynamics

Aero-dynamics

Waves &Currents

Wind-InflowPower

GenerationRotor

Dynamics

Substructure Dynamics

Foundation Dynamics

DrivetrainDynamics

Control System

Soil-Struct.Interaction

Nacelle Dynamics

Tower Dynamics


State of the Art Modeling & LimitationsWind-Inflow

Current ApproachCurrent Approach LimitationsLimitations

IEC-specified deterministic, discrete gusts/direction changes

IEC-specified turbulence (TurbSim)

Idealistic

Neutral stabilityconditions only

TurbSim includes models for site-specific environments:– flows over flat, homogenous

terrain– flows in/near multi-row wind

farms– flows at the NWTC Test Site

(complex terrain)– flows in the Great Plains

with/without the presence of a low-level jet (LLJ)

Need data between 120m – 230m to validate LLJ model

Need data above 50m within wind farms to validate and expand wind farm models

Need data from avariety of climates

Need offshoredata

De

sig

nD

es

ign

Re

sea

rch

Re

sea

rch

Richardson Number

-0.2 -0.1 0.0 0.1 0.2

Da

ma

ge

eq

uiv

ale

nt

loa

d


State of the Art Modeling & LimitationsAerodynamics & Aeroacoustics


Aerodynamics:– blade-element/momentum– generalized dynamic wake– empirical corrections:

• rotational augmentation• dynamic stall, skewed flow

Aeroacoustics:– advanced empirical models

Post stall and high yaw aerodynamics not well predicted:– rotational augmentation– dynamic stall/unsteady wake coupling

Accurate noise predictions for airfoils, but less so for turbines:– no tower shadow model– inaccurate tip noise model

Aerodynamics:– vortex-wake

methods

– CFD

Aeroacoustics:– nonlinear propagation models

– CAA

Need more experience & expertise with codes

Need aerodynamic wake and pressure distributionmeasurements

Need full windturbine acousticmeasurements

De

sig

n (

De

sig

n (AeroDyn

AeroDyn

))R

es

earc

hR

es

earc

h


State of the Art Modeling & LimitationsOffshore Waves & Hydrodynamics (HydroDyn)


Diffraction term only valid for slender base

No wave radiation or free surface memory

No added mass-induced coupling between modes

No nonlinear steep / breaking waves

No 2nd order effects:– slow-drift

– sum-frequency

No sea ice loading Need validation data

De

sig

n (

Fix

ed

)D

es

ign

(F

ixe

d)

Re

sea

rch

(F

loa

tin

g)

Re

sea

rch

(F

loa

tin

g)

Regular Wave

Irregular Wave

HydrodynamicLoad (Morison)FInertia + FDrag

Nonlinear WaveSolver

Wave Spectrum

CAddedMass

, CDrag

from Tables and/or Experiment

StructuralDynamics

StructuralDynamics

Freq.-Domain,Potential-Flow

Solver (WAMIT)

Wave Spectrum

PlatformMotions

IFFT to findWave Excitation

FScattering

Hydrodynamic LoadFScattering + FRadiation+ FBuoyancy + FDrag

HydrodynamicLoads

CT to findRadiation

Kernel

PlatformGeometry


State of the Art Modeling & LimitationsStructural Dynamics


Combined modal/multibody formulation (FAST):– modal:

• blades, tower

– multibody:• platform, nacelle,

generator, hub, tail

Deflection limits Conventional config-

urations only:– no coupled modes

– no flap/twist coupling

– no precurve

– no presweep

Multibody (MSC.ADAMS®) Finite-element method (FEM)

Modeling gearboxdynamics is difficult

Difficult to obtainreduced order modelsfor controls & stabilityanalysis

Computationallyexpensive

De

sig

nD

es

ign

Re

sea

rch

Re

sea

rch

GE 3.6 MW Prototypewith Precurved Blades

1st mode2nd mode

Conventional 3-Bladed Upwind


Program ContributionsUsers & Certification

ADAMS FASTUS Academic 7 18US Government 9 10US Industry 15 25International 9 21

Total 40 74

University of MassachusettsUniversity of Massachusetts


Program ContributionsSuccess Stories

AOC 15/50

Clipper 2.5MWLiberty

Bergey XL50

SouthwestWindpower

STORMNorthWind 100

GE 1.5MW


Program ContributionsDevelopment & Support

Why does the U.S. DOE support codes development?:– design codes are a practical way

for us to transfer wind energy knowledge to the industry

– allows for customization flexibility– commercial products are black

boxes

We support U.S. wind industry through:– websites– technical support– solicitation of user requirements– workshops

NWTC Design Codes Website


Current & Future WorkWind-Inflow

Current work:– implemented Great Plains LLJ spectral model– use this spectral model to determine the effect

these jets have on multi-MW LWSTs– document the development of TurbSim

Future plans (next 2 years):– analyze available Lamar LIDAR data to further

validate Great Plains LLJ spectral model– hold a workshop on inflow turbulence issues

and TurbSim training

Future opportunities:– plan field experiment to collect data on

turbulence within large, multi-MW wind farms– form a multi-discipline, synergistic effort to

understand the role of coherent turbulence on turbine drivetrain fatigue

Sample TurbSim Wind Profiles

0

100

200

300

400

500

5 10 15 20

Wind Speed (m/s)

Hei

gh

t A

bo

ve G

rou

nd

Lev

el (

m)

Power law

Diabatic (Log)400m jet

260m jet100m jet


Current & Future WorkAerodynamics & Aeroacoustics

Current aerodynamics work:– improved fidelity of unsteady wake model– tower influence

Current aeroacoustics work (reduced scope):– wind tunnel tests (Virginia Tech)– CFD, CAA & propagation codes (Penn State)

Future plans (next 2 years):– rewrite AeroDyn – make modular;

provide hooks for other aerodynamic models– validation using wind tunnel (NASA Ames)

and field measurements– add tower shadow noise model

Future Opportunities:– more wind tunnel and field tests– improve codes:

• aerodynamics – vortex-wake and CFD methods

• aeroacoustics – CAA prediction for tower shadow and tip noise

CFD of Blade Tip Vortex (Uzun et al, 2006)


Current & Future WorkOffshore Waves & Hydrodynamics

Current work:– Develop HydroDyn for linear

hydrodynamic loading of fixed-bottom and floating systems

– benchmarking via participation in IEA Annex XXIII OC3

Future plans (next 2 years):– offshore foundations:

• implement p-y & t-z curves

– mooring dynamics:• interface LINES module (MIT)

– support SeaCon studies– WFO analysis of ITI floating

barge concept

Future opportunities:– add nonlinear breaking waves– add sea ice loading– add 2nd order effects– experimental validation

Sample OC3 Simulation Results

20000.0000

25000.0000

30000.0000

35000.0000

40000.0000

45000.0000

50000.0000

55000.0000

60000.0000

65000.0000

70000.0000

0 10 20 30 40 50 60Simulation Time (sec)

NREL FAST TwrBsMyt (kN·m)

GH Bladed TwrBsMyt (kN·m)

Elsam FLEX5 TwrBsMyt (kN·m)

SWE FLEX5 TwrBsMyt (kN·m)

NREL ADAMS TwrBsMyt (kN·m)

DNV HAWC TwrBsMyt (kN·m)

Risoe HAWC TwrBsMyt (kN·m)

Risoe HAWC2 TwrBsMyt (kN·m)

Siemens BHawC TwrBsMyt (kN·m)


Current & Future WorkStructural Dynamics

Straight bladeexternal shape

Internalcomposite

materials lay-up

PreComp or

NuMAD(analysis)

Coupledstructuralproperties

BModes(isotropic material)

Coupled modes

Blade: rotorspeed, pitch,precone, etc.

Uncoupledstructuralproperties

Tower:guy wires

Current Work Straight bladeexternal shape

Internalcomposite

materials lay-up

PreComp or

NuMAD(analysis)



FAST(uncoupled EoM)

Coupled modes


Uncoupledstructuralproperties

Tower:guy wires

Future Plans(next 2 years)

Straight bladeexternal shape

Internalcomposite

materials lay-up

PreComp or

NuMAD(analysis)

Design loads

PreComp(inverse design)



FAST(uncoupled EoM)

Coupled modes


Curved bladeexternal shape

Tower:guy wires

BModes(anisotropic material)

FAST(coupled EoM)

FutureOpportunities


Current & Future WorkNew Horizons

Gearbox dynamics:– gearbox failures might be the result

of our codes inability to capture theinternal gear & bearing loads properly

Stability analysis:– the potential for instabilities increase

for advanced concepts like flexiblerotors and floating turbines

Tower shadow:– need tower wake measurements and

model updates to support designimprovements of downwind rotors

Code validation:– all models must be validated with experimental data

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