Maciej Karczewski, Michal Kulak, Damian KadrowskiMichal Lipian, Filip Grapow, Malgorzata Stepien, Katarzyna Telega, Dominika Raszewska, Piotr Baszczynski, Jeremiasz Czarnecki, Rafal Skalski, Pawel Rogowski, Lukasz Pokrzywka,

Marcin Miller, Karol Zawadzki

Bloomington, MN, USA, 04/10/2018

Rapid questions – rapid prototyping – rapid answers: 3d printing in small wind turbine tests

Our people behind the success

3d printing in lab scale…

Question: How to conduct load tests for a 3d printed wind turbine blade?

Prototype:Small scale prototype 1:6 scale – bench and force platform

Answer:…. It’s coming!

Blade testing standard BS EN 61400-23:2014

Mass/COG of the blade

Static load test

Fatigue load test

X

Y

Z

Test procedure

Natural frequencies of the blade

Static test – design load caseCharacteristics of a wind turbine stage

@ 18 m/s wind speed

Rotational speed range 300 rpm to 7100 rpm

Increment of 200 rpm between each test

5

Characteristics of a wind turbine stage

0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Pow

er (

W)

Rotational speed (rpm)

Maximum load at 3900 rpm @ wind speed of 18 m/s

1st flapwise at 4980 rpm

Static test – design load case

Characteristics of a wind turbine stage

Maximum load at 3900 rpm @ wind speed of 18 m/s

1st flapwise at 4980 rpm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 0.025 0.05 0.075 0.1 0.125 0.15 0.175

Shea

r fo

rce

(N)

Radial distance (m)

Shear force distributions F=f(r/R) @3900 rpm

Shear Z (N)Shear X (N)

-0.2

-0.1

0.0

0.1

0.2

0.3

0 0.025 0.05 0.075 0.1 0.125 0.15 0.175

Mo

men

t (N

.m)

Radial distance (m)

Moment distributions M=f(r/R) @3900 rpm

Mx (Nm)

Mz (Nm)

My (Nm)

Static test – design load case

0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Pow

er (

W)

Rotational speed (rpm)

8

Ø0,4 mm nylon strings

3D printed blade

Holder

1st stage beams

2nd stage beamWhiffle-tree design

Static test – design load case

Turnbuckle

Ø0,4 mm nylon strings

3D printed blade

Holder

1st stage beams

2nd stage beamWhiffle-tree design

Turnbuckle:to level the beam

Static test – design load case

Turnbuckle

Ø0,4 mm nylon strings

Counter-weights

3D printed blade

Holder

1st stage beams

2nd stage beamWhiffle-tree design

Turnbuckle:to level the beam

Counter-weight: to balance the beam

Static test – design load case

Whiffle-tree design

Turnbuckle:to level the beam

3d printing turnbuckle bolts and frame Static test – design load case

Whiffle-tree design

Turnbuckle:to level the beam

3d printing turnbuckle bolts and frame

Design with channels and holders for 3d printing

Easy: rope slides into the channel

Secure: pin is locked between the holders

Fast: pin is knotted to the rope before assembly

Static test – design load case

Counter-weight: to balance the beam

Blade testing

Mass (g) Primary load (N)

78 0,765

206 2,02

362 3,55

791 7,76

1040 10,2

1130 11,1

1240 12,2

1370 13,4

1490 14,7

1540 15,1

1620 15,9

1830 17,9

2030 19,9

2170 21,3

3430 33,6

Design load case

Nylon string was torn apart

… while 3d printed blade returned to its original shape!

Static test – design load case

Test results (deflection)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 500 1000 1500 2000 2500

Bla

de

def

lect

ion

(cm

)

Primary mass (g)

Deflection

Tip

Saddle 4

Saddle 3

Saddle 2

Static test – design load case

Test results (deflection)

Static test –design load case

y = 1870x

0

2

4

6

8

10

12

0 0.002 0.004 0.006

Stre

ss (

Mp

a)

deflection (m)

Stress – deflection @ Saddle 2

y = 904x

0

5

10

15

20

0 0.005 0.01 0.015 0.02

Stre

ss (

Mp

a)

deflection (m)

Stress – deflection@ Saddle 3

Test results (Young modulus)

y = -7,4226x + 2,2341R² = 0,90

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 0.05 0.1 0.15 0.2E

(Gp

a)Radial distance (m)

Young modulus evolutionRadial distance (m)

0,11 0,14 0,16

Pri

mar

yLo

ad(N

)

10,2 1,34 1,02 0,99

11,1 1,48 0,94 0,88

12,2 1,34 1,11 1,10

13,4 1,43 1,04 1,00

14,7 1,32 1,10 1,09

15,1 1,45 1,07 1,03

15,9 1,40 1,15 1,14

17,9 1,35 1,23 1,25

19,9 1,67 1,18 1,13

21,3 1,69 1,33 1,30

Average (GPa) 1,45 1,12 1,09

E=1,95 GPa – Young modulus of ABS according to Zortrax

Static test –design load case

Nowadays…

Rapid question: How much does a winglet increase power output of a small wind turbine?

Rapid prototype:Small scale prototype 1:6 scale – wind tunnel

Rapid answer:By about 2-3%

3d printing for lab test…

Rotor

Bearing unit Torquemeter Generator

3d printed rotor, torquemeterand generator housings

0

0.2

0.4

0 2 4 6 8 10

Cp

TSR

Cp vs TSREXP WT IMP12.5 m/s

Qblade BEM12.5 m/s

Yd the perpendicular distance to the neutral axis

Open field test to quantify real data

0

20

40

60

80

100

120

0 2 4 6 8

Pow

er [

W]

Wind speed [m/s]

Cpavg = 0.65, AF=99% OPEN FIELD TEST

Cpavg = 0.75, AF=100% 3D CFD

TSRavg = 6.76, Vavg=3.1 m/s

TSRavg = 6.00, Vavg=5.0 m/s

Concept

Verification

Empirical model

Empirical test

Product

No

Yes

Design Exploration

No

Yes

ValidationWT

correction

Yes

No

Aerodynamic

numerical model

Verification

Aeroelastic

numerical model

ISO/IEC

standard

WT correction

ISO/IEC

standard

Algorithm for the innovative product development in the field of aerodynamics using multiple levels of numerical-experimental research integration