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 Detail Simulate Field Test Analyze Loads “Tune” Model 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 PhaseTest and Verification Phase Conceptual Design Preliminary Design and Analysis Component Qualification Tests Performance and Prototype Loads Tests Detailed Design and Analysis Final Design Reliability Tests Design Refinements Structural Detailed Design Mech. & Electrical Design DESIGN REFINEMENT Type Certification Load Case Analysis Control & Protection System Maintenance Manual Installation Manual Operating Manual Personal Safety Manufacturing Quality Load Verification Dynamic Behavior Certification DocumentationType Testing Certification Loads Test Power Performance Dynamic Behavior Noise Safety Test Power Quality Define Certification Requirements

Design always starts with loads Component sizing Performance Control requirements Electrical requirements Component costs Life estimates And ends with cost, performance and reliability

Wind Turbine Load Simulators AeroRotor DynDrive 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) Time series output

Blade Element Forces 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)

Another way to look at turbulence Mean flow with superimposed eddies

Energy Spectrum of Wind Speed Fluctuation in the Atmosphere Wind Modeling Turbulence Model Forecasting 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*  *V 3 *A)  where: P = power in [W]  = air density in [kg/m 3 ] V = wind speed at hub height in [m/s] A = rotor swept area in [m 2 ] 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 Torsion Blade Flatwise Deflection Tower Deflection Blade Edgewise Deflection Yawing Rolling Pitching Wind Tower Shadow Mass Loads Non-stationary Aerodynamic Loads Centrifugal Forces Boundary Layer Oblique Inflow Gyroscopic Forces 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?