B No.2012-JBR-0385

2013 The Japan Society of Mechanical Engineers

*1

*2

*3

*4

Yoshiaki TANZAWA*1 , Sota SHIMIZU, Yoshitaka INOUE and Yukimaru SHIMIZU

*1 Nippon Institute of Technology Dept. of Product Engineering & Environmental Management

4-1 Gakuendai, Miyashiro-machi, Saitama, 345-8501 Japan

The vertical axis wind turbine can correspond to the wind direction change in principle and is possible to increase the output by stack it up vertically. However, it is pointed out that the control is difficult, because the self-start is weak and the rotational speed rises rapidly. In this study, we report on the method by which the generating operation can be continued at ease when the wind of the mean speed from 12m/s to 15m/s blows to the small giro-mill type vertical axis wind turbine and under the situation with large wind speed fluctuation in the vicinity of ground. In this method, firstly, the slide shaft is installed squarely to the rotation axis of the vertical axis wind turbine. The flat plate wing in the tip of this slide shaft is parallel to the plane of rotation under a usual rotational speed, and the axial resistance torque is small. However, the flat plate wing begins to tilt when the rotational speed exceeds a certain value, and it becomes finally right-angled to the plane of rotation, and large axial resistance torque is generated. By this method, the runaway of the vertical axis wind turbine is prevented. In the paper, various problems on this are clarified and are verified through the wind tunnel experiment, and the practicable method has been clarified.

Key Words : Wind Turbine, Wind Power Generation, Flow Drag, Aerodynamic Brake, Vertical Axis Wind Turbine

1.

2000

1012[m/s] 15[m/s]

90

Study on the Aerodynamic Brake of Small Gyro-Mill Type Vertical Axis Wind Turbine (1st Report, Method of the Rotational Speed Continuous Control under the Strong Wind)

* 2012 5 18 *1 345-8501 4-1 *2 *3 *4 E-mail: tanzawa@nit.ac.jp

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1()

2.

C [m] CD [-] CP [-]

H [m] N [-] R [m] [deg] [-]

3.

31 1

1000[mm] 1200[mm] 0.3[m] 1 5[m/s] 600[mm] 485[mm]3% 0.7[m]2 0.5 30021 20W100W

2 3 1000[mm] 150[mm] 1000[mm] NACA0015 2022

Fig. 1 Outline of experimental system and measurement system

Generator

Wind tunnel Encoder

Wind turbine

Anemometer Air Resistance

Brake

Reduction gear

Torque meter Load

Dynamic strain amplifier

Wind speed

Torque

Current Voltage

Wind tunnel controller

Interface

PC

1.0

0.8 0.6

0.4 Constant speed line

1.2 m

1.0

m

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Fig. 2 Vertical axis wind turbine

32 90 321 90 3 90

A B C B A 50 B A A

90

Fig. 3 Slide mechanism and the principle of aerodynamic brake "Popping wing"

45

Fig. 4 Aerodynamic brake "Popping wing" Fig. 5 Parts of aerodynamic brake

150 50

1000

C: Compression coil spring A: Slide shaft (15)

Brake plate

Pin Groove

B: Case

332 40

30

Chord line

Tangent line

Circular orbit of wing

Close up

150

1000

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Table 1 Types and size of brake plate wings

Name Size WDt mm

Plate20 1002002

Plate10 1001002

Plate5 100502

PlateT26 (100160+200100)2

PlateT20 (100100+200100)2

PlateT20t15 (100100+200100)1.5

322 32

3

19 [mm] 1618[mm]

Table 2 Specification of springs

Type a b c d e f

Model number AP160

-051-1.4

AP170

-042-1.8

AP180

-060-1.8

AP190

-080-1.6

AP190

-080-1.8

AP190

-084-1.4

Outside diameter mm 16 17 18 19 19 19

Free length mm 51 42 60 80 80 84

Wire diameter mm 1.4 1.8 1.8 1.6 1.8 1.4

Maximum spring mm 28.3 19.6 30.9 49.9 44.7 51.5

Load capacity N 38.1 71.68 67.92 46.77 64.53 32.31

Spring constant N/mm 1.34 3.66 2.2 0.94 1.44 0.63

Table 3 Combination of springs

Type Fat Thin Spacer mm

A f1 a2 20

B e1 c2 4

C d1 b3 4

(a) Combination of springs A (b) Combination of springs B (c) Combination of springs C

Fig. 6 Relationship between force and extension of slide shaft

0

20

40

60

80

100

120

0 20 40 60 80 100

Exte

nsi

on m

m

Force N

Theoretical

Experimental

0

20

40

60

80

100

120

0 20 40 60 80 100

Exte

nsi

on m

m

Force N

Theoretical

Experimental

0

20

40

60

80

100

120

0 20 40 60 80 100

Exte

nsi

on m

m

Force N

Theoretical

Experimental

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10[kgf]

6()

55

0

22%

323 90 7

(a)-1

0 rpm

(a)-2

300 rpm

(b)

400 rpm

(c)

500 rpm

Fig. 7 State of spring, barycentric position of slide shaft and pin position of

each rotational speed and typical vortex flow pattern around flat plate

(a)-1, (a)-2

D0.0020.003

()

0350[rpm]

Spring Pin

Vortex

Brake plate Rotational axis

r

Center of gravity

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(b) 350[rpm]450[rpm]

(C) 450[rpm]90

D1.121.29

D

()

200

7

100[rpm]200[rpm]

300[rpm]500[rpm]

90

25[m/s]

4.

41 826

15[m/s]200600[rpm]100W300WP

Tip Speed RatioTSRV. Kumar

()

0.9, NACA0015P0.16

2Kumar0.2, 0.25, 0.3, 0.35, 0.375, R/H

1.0, 1.25, 1.5, 1.75, 2.0 5P0.150.2

Fig. 8 Tip speed ratio vs power coefficient

KumarP

P0.5

0.751[m]

1[m]0.9PTSR

()

Kumar9[m] 5.4[m]

0.9

0.2

0.25

0.3

0.35

0.375

Kumars

This experiment

Pow

er co

effic

ient

C P

Tip speed ratio

0.3

0.25

0.15

0.05

0.2

0.1

0 1 2 3 4 5 6

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1/480.02

PTSR

42 9(a)

Wind TurbineW.T. 9(a) 200[mm]100[mm]t2[mm](Plate20) Type A100W 300W 7[m/s] 12[m/s] 100[W] 300W 15[m/s] 300[W] 100W 9[m/s] 30[W]

10[m/s] 300[rpm] 15[m/s] 100[W] 300W 20[m/s] 300[W] 9(b)

7[m/s]200rpm 200[rpm]100W 500[rpm] 300W 300[rpm] 20[m/s]600[rpm]

7[m/s] 200[rpm]

250[rpm]

(a) Wind speed vs wind turbine shaft output (b) Wind speed vs turbine rotational speed

Fig. 9 Results of brake performance experiment (Type A and wind turbine without brake)

10Type C

500[rpm]

220[rpm]

0

50

100

150

200

250

300

350

0 5 10 15 20 25

Win

d t

urb

ine

sha

ft o

utp

ut

W

Wind speed m/s

Type A 100WType A 300WW.T. 100WW.T. 300W

0

100

200

300

400

500

600

700

0 5 10 15 20 25

W.T

. R

ota

tion

al s

pee

d r

pm

Wind speed m/s

Type A 100WType A 300WW.T. 100WW.T. 300W

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Fig. 10 Results of brake performance experiment with Type C (Wind speed vs turbine rotational speed)

11Type C

15[m/s]600[rpm]

15[m/s]

Type C 600[rpm]

20[m/s]

100W

Fig. 11 Results of brake performance experiment with Type C (Wind speed vs wind turbine shaft output)

0

50

100

150

200

250

300

350

0 5 10 15 20 25

Wind speed m/s

Power output W

Type C 100W

Type C 300W

W. T.100W

W. T. 300W

600rpm 600rpm

500rpm

220rpm

Brake plate is horizontal.

Brake plate is vertical.

When the wind

speed rises

When the wind

speed turns down

0

100

200

300

400

500

600

700

0 5 10 15 20 25

Wind speedm/s

Rotational speed

Type C 100W

Type C 300W

W.T. 100W

W.T. 300W

Brake plate is horizontal.

Brake plate is vertical.

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11[m/s]300W14[m/s]

500[rpm]

250[W]150[W]20[m/s]

600[rpm]300[W]

15[m/s]

20[m/s]

20[m/s]

25[m/s]

43 15[m/s]25[m/s]

5[m/s]25[m/s]11

12(a)2011 4 21 13 24112(b)(a)

21114[m/s] A3021 00 21 301

1

114[m/s]21 015[m/s]

21 1825[m/s]

(a) Hour wind speed chart (April 21st 2011) (b) Minute wind speed chart for point A

Fig. 12 Wind speed data for one hour average and one minute interval data for point A

44 34

13134

1/21/3

0

5

10

15

20

25

30

13 14 15 16 17 18 19 20 21 22 23 24

Hour

Wind speed m/s

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Minute

Wind speed m/s

A

20

20

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Fig. 13 Division wing of aerodynamic brake

5.

(1) 90100200

(2)

(3)

(4) 905[m/s] 25[m/s]

(5) 1 90

(1) , Vol. 26(2004), pp. 413-416.

(2) Vol. 27No. 4(2003)pp. 16-19.

(3) 4355813 (2009). (4) (1964)p. 152 (5) (1983)p. 152 p.160, (6) Vimal Kumar, Marius Paraschivoiu, Ion Paraschivoiu, Low Reynolds Number Vertical Axis Wind Turbine for Mars,

Wind Engineering, Vol. 34, No. 4 (2010), pp. 461-476. (7) (2002)pp. 64-66

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