Design Process Supporting LWST

1. Deeper understanding of technical terms and issues

2. Linkage to enabling research projects and

3. Impact on design optimization (and hence COE goals)

Presentation Goal:

Presenter: Sandy Butterfield

Iterative design process

Design Design DetailDetail

SimulateSimulate

Field TestField Test

Analyze Analyze LoadsLoads

““Tune” Tune” ModelModel

Performed at system level and component level •Full system•Blade•Controller•Drive train

Intimately Linked to all Product Development Phases

PRODUCT VALIDATION

Design and Analysis Phase Test and Verification Phase

ConceptualDesign

Preliminary Design and Analysis

ComponentQualification Tests

Performance andPrototype

Loads Tests

Detailed Design and Analysis

Final Design

Reliability TestsDesign

Refinements

Structural Detailed DesignMech. & Electrical Design

DESIGN REFINEMENT

Type Certification

Load Case AnalysisControl & Protection System

Maintenance ManualInstallation ManualOperating ManualPersonal SafetyManufacturing Quality Load Verification

Dynamic Behavior

Certification Documentation Type Testing

Certification Loads Test

Power PerformanceDynamic BehaviorNoiseSafety TestPower Quality

Define Certification Requirements

Wind Turbine Load Simulators

Aero Rotor Dyn Drive Train

Support Structure Dynamics

Control and Protection System

Wind

Inflow Model

Structural Loads

System Dynamics (Aeroelastic) Simulation Model

Modules must interact to capture coupling (mutual influence)

Tim

e se

ries

ou

tpu

t

Blade Element Forces

dQDrag Force

Lift Force

NormalForce

Tangential Force

IncomingFlow Stream

Chord Line

dT

Plane ofRotation

Vrel

V=V0(1-a)

(+)r=r(1+a’)

PT

P

T

dQDrag Force

Lift Force

NormalForce

Tangential Force

IncomingFlow Stream

Chord Line

dT

Plane ofRotation

Vrel

V=V0(1-a)

(+)r=r(1+a’)

PT

P

T

Drag Force

Lift Force

NormalForce

Tangential Force

IncomingFlow Stream

Chord Line

dT

Plane ofRotation

Vrel

V=V0(1-a)

(+)r=r(1+a’)

PT

P

T

Blade Element Momentum Theory Geometry

•Relative inflow magnitude?

•Relative angle of attack (AOA)?

•Rate of change of AOA?

•Blade geometry?

Important:

Turbulent inflow

Rotational speed

Pitch angle

Blade deflections & motions

Yaw angle

Synthesized Turbulence

•Wind field = U (y,z,t)

•Stochastic velocities

•Steady wind shear superimposed

•Rotational sampling effect increases effective wind fluctuations

•Must obey representative turbulence spectra

•IEC model? (standard design)

•Lamar measurements? (low level jets)

•Danish models? (homogeneous)

Energy Spectrum of Wind Speed Fluctuation in the Atmosphere

Wind Modeling

Turbulence ModelForecasting Models

Steady Aerodynamics

• Idealized flow through a wind turbine rotor represented by a non rotating actuator disk (momentum theory).

Wake is primary indicator of flow conditions at disk plane

Steady Aerodynamics

Visualization of rotor wake

Rotor Wake States

Wind Tunnel Airfoil Data

Steady, “two dimensional” data used input to simulator.

(must be “modified” for unsteady, three dimensional case)

Can predict

Can’t predict

Or How do we know they are lying?

• Cp = P / (0.5**V3*A) where:

P = power in [W] = air density in [kg/m3] V = wind speed at hub height in [m/s] A = rotor swept area in [m2] Cp = power coefficient (efficiency)

• Betz limit - Cp max = 16/27 0.59

Definition of Power Coefficient

From momentum theory we know:

Good Equation to Know

OK, one more useful equation

= *R / V where:

= tip speed ratio [ ] = rotation speed [rad/s] R = rotor radius [m] V = wind speed at hub height in [m/s]

Definition of tip speed ratio

(or as my wife used to say the “tip speed and ray show”)

Typical rotor efficiency curves

High tip speed ratio rotors = high efficiency & low solidity (blade area/swept area)

Increasing noise

Simplified Structural Dynamics

Tower TorsionBlade FlatwiseDeflection

Tower DeflectionBlade EdgewiseDeflection

Yawing

Rolling

Pitching

Wind

TowerShadow

MassLoads

Non-stationaryAerodynamic Loads

CentrifugalForces

BoundaryLayer

ObliqueInflow

GyroscopicForces

Gust

Blade Torsion

• Blade vibrations interact with aerodynamic forces = aeroelasticity• Mode shapes and natural frequencies critical

Design Process Constrained by Standards:IEC Certification

Are we done yet?