loadevaluationandstructuralload evaluation and structural...

Load Evaluation and StructuralLoad Evaluation and StructuralLoad Evaluation and Structural

Tests for Vertical Axis Small Wind

Load Evaluation and Structural

Tests for Vertical Axis Small WindTests for Vertical Axis Small Wind

T bi Bl d

Tests for Vertical Axis Small Wind

T bi Bl dTurbine BladeTurbine Blade

Ki-Weon Kang, Ph.D. / Professor

K N ti l U i itKunsan National University

Republic of Korea

Contents

Introduction1

State of Art for Load Evaluation and Structural Test

Load Evaluation for VAWT Blade

2

3 Load Evaluation for VAWT Blade

Structural Tests for VAWT Blade

3

4

Concluding Remarks5

2

11 IntroductionIntroduction1. 1. IntroductionIntroduction

1.1 VAWTs?1.1 VAWTs?

DEMERITs Low efficiency and vibration due to their structural layout.

MERITs Low cut-in torque and insensible to variation of wind direction.

VAWT VAWT i i bl f b i d biVAWTs VAWT is suitable system for urban type wind turbine

3

11 IntroductionIntroduction1. 1. IntroductionIntroduction

1.2 Structural Design Considerations for VAWT1.2 Structural Design Considerations for VAWT

Need to establish the Methods for Load Evaluation and Structural TestNeed to establish the Methods for Load Evaluation and Structural Test

Installing Installing AreaArea

VAWTs may be installed in inhabitable area. And they may be integrated in building.

Design Design ConditionsConditions

High structural integrity Low costConditionsConditions Low cost

Loading Loading Centrifugal forces due to rotation

4

ggConditionCondition

g Aerodynamic force due to wind

22 StateState of Artof Art22. State. State of Artof Art

2.1 Load Evaluation for Small Wind Turbine2.1 Load Evaluation for Small Wind Turbine

• IEC 61400-2 for HAWT- Type of loads- Simplified load model

• Type of loads- Vibration, inertial & gravitational loads, g- Aerodynamic loads- Operational loads- Other loads

• Simplified load model- Design load cases.- loads calculated by simple equations.- Thrust and Torque- Bending and Twisting moments

5

22 StateState of Artof Art22. State. State of Artof Art

2.2 Structural Test for Small Wind Turbine2.2 Structural Test for Small Wind Turbine

• IEC 61400-23 for HAWT- Type of tests 80

100

120 Applied Load by aerodynamic design

Design load = 98.01Nm

n Lo

ad [%

]

80

100

120 Applied Load by IEC 61400-2 (Case H)

Design load = 585.20Nm

n Lo

ad [%

]

- Load directions- Load level

• Type of tests0

20

40

60

App

lied

Load

/ D

esig

n

0

20

40

60

App

lied

Load

/ D

esig

n

- Load based method- Strength based method

• Loading direction

0 40 80 120 160 2000A

Time [sec]0 200 400 600 800 1000

0A

Time [sec]

• Load level

- Flapwise Direction- Edgewise Direction

Load level- Test Load = S.F.х Design Load- S.F. = Safety Factor(1.1)

6For VAWT Blade?

33 LoadLoad Evaluation for VAWT BladeEvaluation for VAWT Blade33. Load. Load Evaluation for VAWT BladeEvaluation for VAWT Blade

3.1 Specifications for VAWT3.1 Specifications for VAWT Specification for Blade I(400W)

Blade shape Straight / 223RPM

Chord 296.3 mm

Blade number 4

Height of the rotor 1800 mm

Radius of the rotor 600 mmBlade I

Blade shape Straight / 134RPM

Chord 296 3 mm

Specification for Blade II(600W)

Chord 296.3 mm

Blade number 4

Height of the rotor 3007 mm

Blade II Radius of the rotor 1000 mm

Properties of Al-5052

7

Tensile strength

Yield strength

Modulus of elasticity

Poisson’s ratio

Elongation

193MPa 89.6MPa 70.3GPa 0.33 30%


3.2 Aerodynamic Analysis3.2 Aerodynamic Analysis

Analysis for each blade I and IIAerodynamic analysis : Fixed & rotated : 90˚ 45˚ for cutAerodynamic analysis : Fixed & rotated : 90 , 45 for cut

out(25m/s), Extreme(30m/s) Centrifugal force : 2mrF Tangential and Radial directions for calculated forces Load direction of blade

0V

UP-outboard Inboard Down-outboard

0V

x

y

0

1 2 3

x

y

8

(a) 90°case (b) 45°case

Definition of azimuth angle Three regions of blade for vertical-axis wind turbine


3.2 Aerodynamic Analysis Results3.2 Aerodynamic Analysis Results

TypeAzimuth

[degree]

Wind speed

[m/s]State

Radial force

[N]

Tangential

force

Aerodynamic and centrifugal force for Blade I and II

[degree] [m/s] [N][N]

45°

25 rotated 2315.10 23.41

30 fixed 381 48 64 99I

30 fixed 381.48 64.99

90°

25 rotated 2163.78 47.21

30 fixed 315.50 56.26

Load direction

Aerodynamic force

Centrifugalforce

TypeAzimuth

[degree]

Wind speed

[m/s]State

Radial force

[N]

Tangential

force

[N]

force force

Radial force

II

45°

25 rotated 3435.69 57.37

30 fixed 548.24 129.10

25 d 3194 68 113 30

Aerodynamic force

Tangential force

9

90°

25 rotated 3194.68 113.30

30 fixed 619.00 108.00

44 Structural TestsStructural Tests for VAWT Bladefor VAWT Blade44. Structural Tests . Structural Tests for VAWT Bladefor VAWT Blade

4.1 Structural Test Method4.1 Structural Test Method

Linear actuator tester (MTS)

Radial direction

Radial direction

Tangentialdirection

Saddle of each other direction TangentialSaddle of each other direction

Aerodynamic force

Centrifugalforce

Radial force

Tangential direction

Structural test procedure Blade I & Blade II – Load to center of each sections

Radial forceTest set up

10

Performed to Radial & Tangential directions Linear durability tester & using to±50mm load saddle

4 Structural Tests for VAWT Blade4 Structural Tests for VAWT Blade4. Structural Tests for VAWT Blade4. Structural Tests for VAWT Blade

4.2 Structural Test Results for Blade I4.2 Structural Test Results for Blade I

400Load-Displacement for Blade I

PP--δδ curve for Tangential Direction in Blade Icurve for Tangential Direction in Blade I1400

Force-Displacement for Blade I 450

500Force-Displacement for Blade I T ti l U O tb d

200

250

300

350 loading

Tangential_Down-Outboard

N]800

1000

1200 loading

Tangential_Inboard

[N]

250

300

350

400

450 loading

Tangential_Up-Outboard

[N]

50

100

150

200

Forc

e [

Design Load 64.99N

200

400

600Fo

rce

[

Design Load 64.99N50

100

150

200

250

Forc

e

Design Load 64.99N

0 10 20 30 40 50 600

Displacement [mm]

Up-outboardSection InboardSection Down-outboardSection

0 10 20 30 40 50 600

Displacement [mm]0 10 20 30 40 50 60

0

Displacement [mm]

Pop-in 135N Pop-in 487N Pop-in 101N

11

Ultimate Load Ultimate Load ˃˃˃˃ 65N Design Load 65N Design Load → Structural Integrity→ Structural Integrity



Deformed Blade I for Tangential DirectionDeformed Blade I for Tangential Direction

DeformationDeformation

12

Deformation blade I for tangential direction



900

1000Load-Displacement for Blade I R di l I b d700

800Load-Displacement for Blade I Radial Up outboard

PP--δδ curve for Radial Direction in Blade Icurve for Radial Direction in Blade I

450

500Load-Displacement for Blade I

500

600

700

800

900 p- curve

Radial_Inboard

e, [N

]

400

500

600

700 p- curve

Radial_Up-outboard

e, [N

]

250

300

350

400

450 p- curve

Radial_Down-outboard

, [N

]

100

200

300

400Fo

rce

Allowable load for 190RPM (676.27N)

0

100

200

300

Forc

e

Allowable load for 182RPM (310.25N) 50

100

150

200

Forc

e,


0 5 10 15 20 25 30 35 40 450

Displacement [mm]0 10 20 30 40 50 60 70 80 90 100

0

Displacement [mm]

Up-outboardSection

P i 310N

InboardSection

P i 676N

Down-outboardSection

P i 310N

0 5 10 15 200

Displacement [mm]


579NDesign 1 158NDesign 579NDesign

13

Ultimate load Ultimate load ≤ Centrifugal load at 182RPM ≤ Centrifugal load at 182RPM → Failure → Failure



Deformed Blade I for Radial DirectionDeformed Blade I for Radial Direction

Deformation DeformationDeformation

14

Deformation blade I for radial direction


4.3 Structural Test Results for Blade II4.3 Structural Test Results for Blade II

800Force Displacementfor Blade II

2000Force_Displacement for Blade II

400Force_Displacement for Blade II

PP--δδ curve for Tangential Direction in Blade IIcurve for Tangential Direction in Blade II

400

600 Loading Point

_ pTangentail_#1

, [N

]

1000

1500 Loading Point

Tangentail_#2

, [N

]

200

250

300

350 Loading Point

_ pTangentail_#3

, [N

]

200

Forc

e,

Design Load129.1N

500Fo

rce,

Design Load129.1N

50

100

150

Forc

e,

Design Load129.1N

Design Load 129.1N

Design Load 129.1N

Design Load 129.1N

0 30 60 90 120 1500

Displacement, [mm]0 30 60 90 120 150

0

Displacement, [mm]0 30 60 90 120 150

0

Displacement, [mm]

Up-outboardSection

P i 340N

InboardSection

P i 396N

Down-outboardSection

P i 251N

P-δ curve for Blade II tangential direction


15

Ultimate Load Ultimate Load ˃˃˃˃ 129N Design Load 129N Design Load →→ Structural IntegrityStructural Integrity



Deformed Blade II for Tangential DirectionDeformed Blade II for Tangential Direction

DeformationDeformation

16

Deformation blade II for tangential direction



900

1000Load-Displacement for Blade II

PP--δδ curve for Radial Direction in Blade IIcurve for Radial Direction in Blade II

900



500

600

700

800

900 p- curve

Radial_Down-outboard

[N]

500

600

700

800

900 p- curve

Radial_Up-outboard

[N] 4000

5000

6000 p- curve

Radial_Inboard

[N]

100

200

300

400

500

Forc

e,


100

200

300

400

500

Forc

e,


1000

2000

3000Fo

rce,

Allowable load for 134RPM(1347.68N)

0 10 20 30 40 50 600

Displacement [mm]

Up-outboardSection InboardSection Down-outboardSection

0 10 20 30 40 50 600

Displacement [mm]0 5 10 15 20

0

Displacement [mm]


860NNDesign 1 718NDesign 860NDesign

17

Ultimate load ≤ Centrifugal load at 108RPM → FailureUltimate load ≤ Centrifugal load at 108RPM → Failure



Deformed Blade II for Radial DirectionDeformed Blade II for Radial Direction

D f tiDeformation

Deformation

18

Deformation blade II for radial direction

5 Concluding Remarks5 Concluding Remarks5 Concluding Remarks5 Concluding Remarks5. Concluding Remarks5. Concluding Remarks5. Concluding Remarks5. Concluding Remarks

ConclusionsConclusions Aerodynamic and Centrifugal Forces Evaluation for VAWTs Structural Tests for VAWT in Tangential and Radial Directions

Suggestions & Further TasksSuggestions & Further Tasks

Load Radial forces should be considered.

I A d i l i li bl ?

Suggestions & Further TasksSuggestions & Further Tasks

Evaluation Is Aerodynamic analysis reliable?

Are there simple load calculation methods for aerodynamic force?

Test Method

Is test for only blade sufficient? What about the vertical axis?

Displacement control or Load control?

Is there analogy between actual and test load distributions?

19

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