Dave Corbus, Craig Hansen Presentation at Windpower 2005 Denver, CO May 15-18, 2005

Dave Corbus, Craig Hansen

Presentation at Windpower 2005

Denver, CO

May 15-18, 2005

Test Results from the Small Wind Research Turbine (SWRT) Test

Project

2SWRT Project

SWRT Test Background

• SWRT Test

•Supply data for model validation of small furling wind turbines

•Increase understanding of furling and small wind turbine dynamics

•Further state-of-the-art test procedures for small wind turbines

3.51"3.30"3.72"

3SWRT Project

SWRT Testing and Model Development• SWRT Test

•Three different turbine configurations tested

• Most comprehensive small turbine test

• Upgrade FAST model to include furling

•Perform model comparisons between SWRT FAST and ADAMS models and FAST and SWRT

• Models often break down more for small turbine conditions

•In and out of stall more

•More yawed flow conditions

•Dynamically active turbine

4SWRT Project

SWRT Test Description

Yaw slip rings and encoder

Furl Sensor

Sonic anemometer junction box

Shaft sensor

Flap and edge blade strain gages

Tower leg load cell “washers”

Rotor slip ring, encoder, and amplifiers

5SWRT Project

SWRT shaft sensor - first accurate small turbine thrust

measurements Measures Shaft

0/90 bending, torque, thrust on fixed frame

4 by 4 cross-talk matrix

Critical path load is the shaft bending from gyroscopic loads

6SWRT Project

Pre-testing Turbine Characterization

Data for modeling included:

– Tail assembly and main frame:

• Weight, Cg, bi-filar, moment of inertia about yaw axis

– Magnet can Cg and moment of inertia

– Tail damper properties– Exact turbine

geometries– Blade modal test

7SWRT Project

Max and Mean Furl vs. Mean Wind Speed

-20

0

20

40

60

80

5 10 15 20

Mean Wind Speed, m/s

Fu

rl, d

eg

Max Furl Furl

8SWRT Project

Yaw Rate vs. Mean Wind Speed

-150

-100

-50

0

50

100

150

5 10 15 20

Mean Wind Speed, m/s

Ya

w R

ate

, de

g/s

Max yaw rate Mean yaw rate Min yaw rate

9SWRT Project

Rotor Speed vs. Mean Wind Speed

0

100

200

300

400

500

600

5 10 15 20Mean Windspeed, m/s

RP

M

RPM mean RPM max RPM min

10SWRT Project

Furl vs. Thrust

0

10

20

30

0 500 1000 1500 2000 2500

Thrust, N

Fu

rl,

de

g

Mean Furl versus Thrust

11SWRT Project

SWRT Furling Event – Time Series Plot

320320 340340 360360 380380 400400 4204200

10

20

30

40-1000

0

1000

2000

3000

4000

150

200

250

300

350

400

450

Win

d S

pee

d &

Fu

rl A

ng

le

Time, seconds

Sh

aft

Th

rust

Ro

tor

RP

M

320 340 360 380 400 420

-60

-30

0

30

60

90Y

aw E

rro

r

12SWRT Project

Furling and Center of Thrust

0

5

10

15

20

25

30

35

40

45

50

5 7 9 11 13 15 17 19 21

Time, seconds

Fu

rl, Y

aw E

rro

r (d

egre

es)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Cen

ter

of

Th

rust

(m

eter

s)

furl yaw error center of thrust

13SWRT Project

SWRT Test Configurations

All configurations tested with inverter load – Total of 514 10-minute

records

A few resistor load files taken for each configuration– Some scatter in rpm-

torque curve from inverter controller hysteresis

SWRT Configuration

A B C

Airfoil SH3052 SH3052 SH3055

Lateral shim

4 degree

none none

Swept Area/Rotor Diameter

26.4 m2/ 5.8

m

26.4 m2/ 5.8

m

35.3m2 /

6.7 m

Blade pitch

11.5 11.5 9.5

14SWRT Project

Furl vs. Wind Speed for Different Configurations

0

5

10

15

20

25

30

35

40

45

50

9 11 13 15 17 19 21

Mean Windspeed, m/s

Fu

rl D

eg

ree

s

Mean Config A

Mean Config B

Mean Config C

Poly. (MeanConfig C)Poly. (MeanConfig A)Poly. (MeanConfig B)

Configuration C

Configuration B

Configuration A

15SWRT Project

Thrust vs. Wind Speed for Different Configurations

0

500

1000

1500

2000

2500

3000

3500

5 9 13 17 21Mean Windspeed, m/s

Th

rus

t, N

Mean Config AMean Config BMean Config C

16SWRT Project

Ratio of Tail/Met Wind Speed vs. Wind Speed

0%

20%

40%

60%

80%

100%

5 10 15 20Wind Speed, m/s

Ra

tio

Ta

il/M

et

WS

, %

Tail/Met WS Ratio A

Tail/Met WS Ratio C

17SWRT Project

Power/Thrust Ratio for Configurations A and C

0

1

2

3

4

5

6

5 10 15 20Wind Speed, m/s

Po

we

r/T

hru

st

Ra

tio

Power/Thrust Ratio Config C

Power/Thrust Ratio Config A

18SWRT Project

Furling and Inflow

Use sonic anemometer and meteorological data

Correlate inflow parameters and furling

Shows significance of vertical wind component and coherent turbulent kinetic energy

19SWRT Project

Furling and Richardson Number

SWRT Configuration "A" Mean Furling Angle & Mean Coherent Turbulent Kinetic Energy (Coh TKE)

vs Vertical Stability (Ri)

2-50m layer Richardson number stability parameter, Ri

-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15

Meanfurling angle (deg)

0.001

0.01

0.1

1

10

100

Hub mean Coh TKE

(m2/s2)

0

10

20

30

40

50

60

Mean Furling AngleMean Coh TKE

Max ART Response

20SWRT Project

- CoTKE and vertical gust variance for two files with same wind

speed and different furl

Cycles/min0.1 1 10 100

RM

S C

oh

TK

E (

m2/s

2)

0

2

4

6

8

10

12

Coherent TKE

Frequency (Hz)0.001 0.01 0.1 1 10

RM

S C

oh

TK

E (

m2/s

2)

0

2

4

6

8

10

12

FurlNo Furl

Wavelength in Rotor Diameters

1 10 100 1000

RM

S C

oh

TK

E (

m2/s

2)

0

2

4

6

8

10

12

Vertical Gust Velocity Variance

Frequency (Hz)

0.001 0.01 0.1 1 10

w' V

aria

nce

Sp

ectr

a (m

2/s

2)

0.0

0.1

0.2

0.3

0.4

0.5

Wavelength in Rotor Diameters

1 10 100 1000

w' V

aria

nce

Sp

ectr

a (m

2/s

2)

0.0

0.1

0.2

0.3

0.4

0.5

Cycles/min0.1 1 10 100

w' V

aria

nce

Sp

ectr

a (m

2/s

2)

0.0

0.1

0.2

0.3

0.4

0.5

21SWRT Project

SWRT Test & Simulation ModelsSWRT FAST Model

Extensive turbine properties provided by NREL

12 degrees-of-freedom (DOFs) used– Blade flexibility 2 flap and 1 edge mode DOF per blade– Drivetrain 1 variable generator speed DOF with

torque-speed look-up table– Nacelle yaw 1 yaw DOF– Tail-furl 1 tail-furl DOF with nonlinear

damper

Aerodynamics– Used dynamic stall and dynamic inflow options in AeroDyn– Original airfoil data based upon Selig wind tunnel tests

• Tapered tip section airfoil data based upon XFoil predictions by Tod Hanley

– Airfoil data “tuned” after comparing with measured Cp-TSR data (very limited range)

Dynamics verified via comparisons with ADAMS

22SWRT Project

Model & Test Comparisons Configuration A Statistics (Inverter Load)

0

100

200

300

400

500

600

700

6 8 10 12 14 16 18Mean Windspeed, m/s

Ro

tor

Sp

eed

, RP

M

Test mean Test max

FASTMean FASTMax

23SWRT Project

Model & Test Comparisons Configuration A Statistics (Cont’d.)

0

15

30

45

60

75


Fu

rl A

ng

le, d

eg

Test mean

Test max

FASTMean

FAstMax

24SWRT Project


0

1

2

3

4

5

6


Ro

tor

Th

rust

, kN

Test mean Test maxFASTSNWind Mean FAST SNWindMaxFASTTurbmean FASTTurbMax

25SWRT Project


0

5

10

15

20

25

6 10 14 18Mean Windspeed, m/s

Yaw

Err

or,

deg

Test mean

FAST Mean

26SWRT Project

Model & Test Comparisons - Configuration B with Resistor Load - Mean wind speed 17.2 m/s

0 100 200 300 400 500 600200

300

400

500

600

700

R

oto

r S

pe

ed

, R

PM

Time, s

Test FAST

27SWRT Project


0 100 200 300 400 500 600

0

10

20

30

40

50

F

url

An

gle

, d

eg

Time, s

Test FAST

28SWRT Project


0 100 200 300 400 500 6000

1

2

3

4

5

6

7

Ro

tor

Th

rus

t, k

N

Time, s

Test FAST

29SWRT Project


0 100 200 300 400 500 600

-50

-40

-30

-20

-10

0

10

20

Y

aw

An

gle

, d

eg

Time, s

Test FAST

30SWRT Project

SWRT Summary

Most comprehensive small turbine test data set

Better understanding of small wind turbine dynamic behavior, including thrust and furling

SWRT test data and modeling effort will help make furling design efforts for small wind turbines easier, but furling remains a challenge!

Better test procedures for small turbine testing

Inflow analysis shows effects of turbulence

Fundamental shortcomings in aerodynamic modeling are the main reason for test data and model disagreements– 3-D stall effects (i.e., rotational augmentation)– Uncertainties in skewed wake correction for yawed

flow

Dave Corbus, Craig Hansen Presentation at Windpower 2005 Denver, CO May 15-18, 2005

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Transcript of Dave Corbus, Craig Hansen Presentation at Windpower 2005 Denver, CO May 15-18, 2005