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
Jan 11, 2016
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?