Blade Design Codes

Daniel L. Laird

Wind Energy Technology DepartmentSandia National Laboratories

Albuquerque, New Mexico, USA

Sandia National Laboratories

Design-Process Overview

Airfoil Data

Performance

Aero-ElasticsExtreme Wind

Full-Field Turbulence

Aerodynamics

Controls

StructuralDesign

StructuralProperties

Sandia National Laboratories

Design Codes (U.S. usage)

FoilCheckAirfoilPrep (new)

Airfoil Data

WT_PerfPerformance BLADED

commericalmodal

Aero-Elastics

FASTFree

modal18 dof

Aero-Elastics

ADAMScommercial

multibody dynamics‘unlimited’ dof

Aero-Elastics

IECwindWindMaker

Extreme Wind

TurbSim (new)Full-Field Turbulence

AeroDynfree

AerodynamicsRCAS

freemodal or multibody dynamics

‘unlimited’ dofAero-Elastics

ModesCoModes (planned)

Mode Shapes

SNLWIND-3DSNwind

Prop

FAST

2AD

AM

Spr

epro

cess

orMatLab

(SimuLink)commercialControls

ANSYScommercial

FEAStructural

Design

NuMAD/BPEFree

fea/section props

Focuscommercial

section analysis/fea

FLEX5commercial

Aero-Elastics

PreCompfree

section analysisStructuralProperties

Cosmoscommercial

FEAStructural

Design

StructuralProperties

StructuralProperties

Design Codes (U.S. usage)

FoilCheckAirfoilPrep (new)

Airfoil Data

WT_PerfPerformance BLADED

commericalmodal

??? dofAero-Elastics

FASTFree

modal18 dof

Aero-Elastics

ADAMScommercial

multibody dynamics‘unlimited’ dof

Aero-Elastics

IECwindWindMaker

Extreme Wind

TurbSim (new)Full-Field Turbulence

AeroDynfree

AerodynamicsRCAS

freemodal or multibody dynamics

‘unlimited’ dofAero-Elastics

ModesCoModes (planned)

Mode Shapes

SNLWIND-3DSNwind

Prop

AD

AM

S/W

Tpr

epro

cess

orMatLab

(SimuLink)commercialControls

ANSYScommercial

FEAStructural

Design

NuMAD/BPEFree

fea/section props

Focuscommercial

section analysis/fea

FLEX5commercial

Aero-Elastics

PreCompfree

section analysisStructuralProperties

Cosmoscommercial

FEAStructural

Design

StructuralProperties

StructuralProperties

NuMAD – Structural FEA Analysis

Pre-processor and post-processor for ANSYS

Tailored to design and analyze wind turbine blades

Databasesmaterialsairfoilsloadings

Development guided by industry input

Beam Property Extraction capabilityColors indicate different materials

Sandia National Laboratories

Beam Property Extraction (BPE)• Joint effort between GEC and SNL

• Goal is to automatically produce the 1-D beam element properties needed for an aeroelastic simulation (ADAMS) from the 3-D structural finite element model (NuMAD/ANSYS)

• May be used with legacy ANSYS blade models

ADAMS42 DOF

ANSYS200,000 DOF

• Almost all 3-D finite element analyses of wind turbine blades use layered shell elements with offset nodes

• The offset node formulation of the layered shell elements does not correctly handle torsion

• It appears that the issue is a limitation in FE shell theory rather than an error in the particular implementation (i.e. ANSYS vs. NASTRAN etc.)

Finite Element Analysis – Shell TheoryNodal Offsets

mid-thicknessformulation

offsetformulation

Sandia National Laboratories

Test Case – Hollow Cylinder

nodes@mid-thickness offset nodes@top

01020304050

0 4000 8000 12000

# o f e le m e n t s

aspect ratio ≈1.1radius/thickness=7.5L=20

Max

Tw

ist (

% e

rror

)

# of elements

-200

20406080

0.001 0.01 0.1 1 10 100

a sp e c t ra tio

# of elements =19200radius/thickness = 10L=20

Max

Tw

ist (

% e

rror

)

aspect ratio

-90

-60

-30

0

30

0 10 20 30

aspect ratio ≈3.4# of elements =2880L=20

radius/thickness ratio

Max

Tw

ist (

% e

rror

)

Sandia National Laboratories

Twist-Bend Coupling (24 hr summary)

Bad News:

“The equations are wrong.”K. Wetzel

“The simulation is wrong.”D. Laird

Good News:Tremendous opportunities for improvement

NuMAD

external profile

shell elements

physical thickness representation

now produces mid-thickness model

Glue Together

Sandia National Laboratories