The angles of the kolibrie rotor tipvanes on the rods and on the blades

1111111111111

A. Bruining

Published and distributed by: Delft University Press

Stevinweg 1 2628cN Delft The Netherlands

By order of:

Delft University of Technology Institute for Windenergy

Kluyverweg 1 2629HS Delft The Netherlands

Report IW-R515 October 1988

Carried out within the Dutch Development Program for Wind Energy (NOW-2); by order of the Management Office for Energy Research PEO; financed by the Ministry of Economic Affairs.

CIP-GEGEVENS KONINKLIJKE BIBLIOTHEEK, DEN HAAG

Bruining, A.

The angles of the kolibrie rotor tipvanes on the rods and on the blades / A. Bruining. - Delft : Delft University Press. - 111., fig., tab.

Carried out within the Dutch Development Program for Wind Energy (NOW-2); by order of the the Management Office for Energy Research PEO. - Report IW-R515. - Met lito opg. ISBN 90-6275-496-1

SISO 653.2 UDC 533:621.548 NUGI 834 trefw.: windmolens; aerodynamica .

. copyright~by Delft University Press.

No part of this book may be reproduced in any form by print, photoprint, microfilm or any other means, without written permission from Delft University Press.

Content$

pag.

S~m~y

3

1. Symbols 4

2. Introduction

6

3. Tests and methods 8

3.1 Measuring methods 8

3.1.1 Definition of the angles in the first measuring

method

8

3.1.2 Second measuring method

9

3.2 Accuracy 10

4.

Results 11

5.

References 12

Tables 13

3

-Summary

This report contains the data of the adjusted angles of the tipvanes used on the Kolibrie rotor blades and rods.

Two measuring methods for the determination of these angles were

applied: one method is based on determining the chord vector and the span wise vector of the tipvane. The other method is based on the angles of the mounting parts of the tipvanes.

The theoretical background of the different angles systems, used to de fine the attitude of the tipvane in the 3-dimensional space and the measurement procedure are not included in this report, but is explained in ref. 1.

Due to the unreliability of the position of the chord vector and the span wise vector the results from this first method were not used for further calculations.

All further calculations were carried out with the data from the second method, based on the angles of the mounting parts of the tipvanes.

1. Symbols a b c R vb h or vb vert y A.VC h or e::

offset distance of the tipvane, see fig. 1

distance between center line of the mounting part and

25%

chord point of the Kolibrie tipvane, see fig. 1

chord of the tipvane

rotor tip radius

measurement angle of the tipvane, defined in section

3.1

measurement angle of the tipvane, defined in section

3.1

measurement angle of the tipvane, defined in section

3.1

measurement angle of the tipvane, defined in section

3.1

flapping angle

tilt angle of the tipvane

difference in the tipvane measurement angle vC

h or ,denotes accuracy, see section 7.3 of ref. 1

rotor blade twist angle based on the blade length (m) (m) (m) (m) (degrees) (degrees) (degrees) (degrees) (degrees) (dègrees) (degrees) (degrees)

8 8' 8 ref A g indices a k

5

-incidence angle of the tipvane

mounting part angle, defined in fig. 1

built-in mounting part angle, defined in fig. 1

blade pitch angle measured at the reference surface on the connection of the hub element and the rotor blade

blade tip pitch angle, angle between tip chord and rotor disc plain

sweep angle of the tipvane

(= A

*

cos r ) measured sweep angle

a a

of the tipvane

(= aiR

*

180/n)

tipvane offset angle, see fig. 1

indicates aerodynamic tipvane angles

indicates Kolibrie tipvane angles

indicates flapping angles

(degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees) (degrees)

2. Introduction

For mounting the tipvanes of the Kolibrie rotor on the rotor blades or rods there exist 3 mounting parts. The angles of the mounting parts cannot be adjusted. The only change of geometry is possible by varying the blade root pitch which gives a sweep angle variation.

Mounting part 1 is the oldest one. It gives a moderate lift on the tipvanes. It is also called the break even mounting part, because the Kolibrie rotor produced with this set the same nett power output as without tipvanes.

Mounting part 2 gives the tipvane a very high lift. It was designed to create astrong mass flow increase. Due to the high drag the nett power output was low. This set is called the separation mounting part.

Mounting part 3 has a lift coefficient between mounting part 1 and 2 to avoid the high drag and flow separation.

The same mounting parts can be used for connecting the tipvane on the rotor blade or rod.

The mounting parts have some principal built-in angles. See table 1. With the measuring method of section

7

of ref. 1 it is not necessary

to know what these built-in angles are, because the aerodynamic angles of the tipvane are directly calculated from the measurement angles.

See for an explanation of the various type of angles ref. 1.

The sequence of the

3

Euler angles which should be used is:

1. _{set the incidence angle Bk} 2. set the sweep angle ' \

· \

7

-This is the prescribed sequence of the construction angles, but there was a difference in the actual construction of the mounting parts. The axis on which the tilt angle is introduced is here the non-swept chord vector (index c). For the construction angles the tilt angle is introduced around the swept chord vector (see section

3.

Tests and methods

3.1 Measuring methods

Two measuring methods were used to determine the tipvane angles of the Kolibrie rotor.

The angles of the Kolibrie tipvanes are measured and calculated by the method described in section

7

of ref. land by a method based on the measurements of the geometry of the mounting parts.

For the measuring method of section 7 of ref. 1 a wood en mould was used for determining the chord line. One edge of the mould is exactly parallel with the chord vector. The vertical vector ~ was created with a plumb line.

The tipvane offset angle ~ is directly determined from the geometry by using the distance a (see fig. 1).

~ = ~

*

R

180

(degrees)

The radius R of the rotor is

4.475

m. Since ~ is known, the expression with vc t (see section

7.3

of ref. 1) is used for

ver checking.

3.1.1 Definition of the angles in the first measuring method

1

The line from the

2

chord point of the tipvane at the mounting part towards the rotor shaft is positioned exactly horizontal. The angle between the vertical vector v and the span vector b is then called vb

h or . The angle between v and the chord vector c is vC1 or h . The same angles are measured once again with the line from the

2

chord point of tipvane at the mounting part now positioned exactly vertical. These angles are denoted vb_vert and vC_vert respectively. See fig.

3·

vb

9

-3.1.2 The second measuring method

The second measuring method us es the built-in angles. Ak and Y

k are built-in in the tipvane itself. 8km is built-in in the

mounting part.

The tipvane fits in a such a way in the mounting part that 8

km = 0

if the outside surface of the mounting part is parallel with the local tangent.

8

km can be 'calculated by:

8 = 8' -

~

*

180 = 8' -

~

km R TI

8' is the angle between the outside surface of the mounting part and the tangent of the power blade or rod (see fig. 1). The values of

the offset distance a and 8' are given in table 1.

But the axis of A of the aerodynamic angles coincides with the axis

a

of St' of the blade pitch angle. So the correction of a different

~p

blade tip pitch angle on the aerodynamic angie is made by:

AA a

This relation was used for correcting the sweep angle A of the

a

tipvane, that was connected on the rotor blade for the different

blade tip angle settings. 8

tl.p . was determined from 8 re f and the

blade twist E: (based on the blade length) by:

+ E:

The blade twist E: depends on the rotation speed of the rotor. This

is caused by the limited torsional stiffness of the Kolibrie rotor

blades and the large torsional moment generated by the tipvane. This

blade twist was during the performance measurements determined with strain gages. See table 3a and table 3b and section 3.2 of ref. 2.

At the drag measurements on the rods also different sweep angles A a were used. A slightly different approach was applied: The sweep angle A was now measured on the leading edge of the tipvane.

g

A is the angle of the trailing edge or leading edge with the

g

horizontal plain when the

~

ehord line of the blade or the rad is exaetly horizontal. A is then ealeulated by:

a A A leas Y

a g a

3.2

Aeeuraey

The aeeuraey of the measured angles is in the order of 0.5 degree. Two angles deviated: vC_{h or} of mounting part 2 and ve _ver t of mounting part

3.

In table

3

the eorreeted values are presented.

The aeeuraey was eheeked by ealeulating A ,Y and 8 from the

a a a

original angles 8

k, Ak and Yk (see table 1) by the methad deseribed

in seetion

6.1.2

of ref.

1.

The measured value of ve_{h or} of part 2 was:

ve _hor =

165.92°

This value is larger than for part 1 and

3.

It should be the smallest, beeause 8 of part 2 has the largest value.

a

The measured value of ve _ver t of part

3

was:

ve _vert =

75.33°

The ealeulated value for 8 with this ve _{a ver} t

=

75.33°

was 8 _a

=

14.5°.

This deviates toa mueh from the ealeulation for 8 based on a

Sk' Ak and Y

k, whieh give Sa =

16.8°.

Due to the unreliability of the values in table 3 and table 4 the angles of table 2 are used for further ealeulations.

11

-4.

Results

The results of the original built-in angles are presented in table 1 and the calculations based upon these angles in table 2.

The measurement angles and calculated aerodynamic angles are given in table

3

and table

4.

Due to the unreliability in the measurement angles the calculated aerodynamic angles of table

4

are not used.

For all calculations the aerodynamic angles of table 2 are used.

In table

5

A •

r

and

e

are given without and with flapping angle

a a a

for different A settings such as used by the drag measurements of a

the Kolibrie tipvanes on the rods. A is directly calculated from a

the measured A .

5. References

1 . A. Bruining

2. A. Bruining

3.

A. Bruining

Definition, transformation-formulae and measurements of tipvane angles,

IW-R510, 1987. ISBN 90-6275-424-4.

Performance measurements of the

Kolibrie and FA CT rotor with tipvanes on the full scale experimental wind turbine, IW-R519, 1988.

Tipvane drag measurements on the full-scale experimental wind turbine, IW-R517, 1986.

-

13

-mounting part

1

2

₃

8 tip degrees 0

0

8

8 k degrees

2.73

12.63

9.68

Ak degrees

15

15

15

Y k degrees

25

25

25

a m

0.099

0.107

0.103

et

_degrees

₄

₁₄

₁₁

Table 1: The original angles of the Kolibrie tipvane mounting parts. mounting part

1

2

₃

8_tip degrees

0

0

0

A _a degrees

17.6

21.3

12.3

Y degrees a

23·3

20.0

21.0

8 _a degrees

_9.7

19.8

16.8

Table 2: The original aerodynamic angles calculated from table 1. These values are used for further calculations.

mounting part 1 2 ₃ vb _vert degrees 66.67 70·33 68.67 ve _vert degrees 80.17 70.58 73·33 vb_{h or} degrees 73.92 70.08 78.83 1 ve hor degrees 164.58 160.00 164.17 1jJ degrees 1.14 1.24 1.2 a mm 99 107 103

Table

3:

Measured angles of the

3

Kolibrie mounting parts. 1 eorreeted value for measuring error, value from

ealeulation, based on geometry, (measured value was ve_{h or}

=

165.92°).

Z eorreeted value for measuring error, value from

ealeulation, based on geometry (measured value was ve _ver t

=

75.33°). mounting part 1 2 3 A degrees a 17 .1 20.8 11.5 y _{degrees 23.7 20.1 21.6} a 8 degrees 9.5 19.4 16.8 a 8_tip degrees 0 0 0 z

Table

4:

The calculated aerodynamic angles of the

3

mounting parts for the Liebeck tipvanes of the Kolibrie rotor from the measured angles. Not used for further calculations.

! :

- 15

-~

=

0°

~

=

4°

mounting A A Y

a

A y

a

g a a a _{af) af)}

-

part af) degrees degrees

1

11

11.97

23·3

9.7

11.65

19.38

8.82

16

17.42

23.3

9.7

16.96

19.48

8.43

2

11

11. 71

20.0

.

19.8

11.45

16.08

18.96

16

17.03

20.0

19.8

16.65

16.17

18.58

3

6

6.43

21

16.8

6.28

17.02

16.33

11

11.78

21

16.8

11.50

17.08

15.95

16

17.14

21

16.8

16.74

17

.17

15.57

Table

5:

The aerodynamic angles without and with flapping angle f)

of the tipvanes of the Kolibrie rotor used by the drag

measurements on the rods A = A leos Y .

f) ::

0

0 _f) ::

4

0

mounting 8 . A Y 8 A Y 8

part tlp a a a af) af) af)

degrees degrees

1

0

17.6

23·3

9.7

1.25 18.85

23.3

9.7

18.35

19·51

8.33

2

0

2.13

20.0

19.8

2.8

24.1

20.0

19.8

23.57

16.34

18.10

3

0

12·3

21.0

16.8

0.8

13.1

21.0

16.8

12.79

17.10

15.85

3.2

15.5

21.0

16.8

15.13

17.14

15.68

5·2

17·5

21.0

16.8

17.09

17.18

15.54

Table

6:

The aerodynamic angles without and with flapping angle f) of the tipvanes of the Kolibrie rotor on the blades used by the performance measurements.

R=4.375m

R :1.,1.75 f f i _

1,

_{I. chord line power blode}

.

or centre line of the rod

\

I

I

I

I

i

i

8km a Hounfing part 1 99 b 2 107 3 103 b

el

99 4° 99 14° 99 11°

I

R=4.475m

'J

Fig. 1: Drawing of the attachment of the Liebeck tipvane on the mounting part

of the Kolibrie tipvane.

.-.

94

,

,

_,

_...

_{_-}

-

-)

"-,

~('~'

f

i.--Y

~

\

'1 \_, . \

~

_I

~ \ ~

_{I . I} I ; ~ \ I ~ 40 75 0 N f-- '--14 ,..-' '-24

~

.-'

~

:;

.-' ['... .-' ~

:::,

~

.-' co . .-' ~ i'- . - '

Fig. 2a: Dimensions of mounting part 1 of the tipvane of the Kolibrie rotor.

'P. Ol -.i M o N

®

14 24 o ~ ... co

CDI

N M N 70

.j

, 12 Haferial Aluminium 51 ST ol Dimensions in mm 0 N N ' , N M

-$J

CD

®

16 14 ~o lil lil 1 0 ~ ~ 36 Hounfing part 2 24 lil ~ 14° 101

Fig 2b: Dimensions of mounting part 2 of the tipvane of the Kolibrie rotor.

~ ~ M

®

12 >-> lD

Haterial AI . ummium 51ST . Olmensions in mm 0 N

<$-(DI

_I

®

~ -2 ~

~I

0

-<$-.~ :;: ~ -':

~

1"

~

(])

I I

N M N

I

I

\~~::::.::::.~~ \~~~~~::::. ::::'::::'~~Il

,

,,\.\ Hounting part 3 24 ). M12

/

t,

(.,,,~-

_~

'

"

\)(

. \

',~\

~ .

\

,

\ \ I I \ I \ \ \ . \ r'--

::;

I"-~

::;

r'-- . / r--

_::::

j r-- ~ . I'-- . / r'-- . /

,

101

Fig. 2c-l: Dimensions of mounting part 3 of the tipvane of the Kolibrie rotor.

o N '!!. ~ M

®

1"

~

~

2" o ~ ~ N o

- 21 -70 16

'4

~I 0 U)

®

70 o N U) 0 . - N . .- .-Hounting part 3 Dimensions in mm

Fig. 2c-~: Dimensions of mounting part 3 for the tipvane of the

v

rorational direction

c

b j 111

V

Cve rt

v

b

vert

v

Fig. 3: The horizontal and vertical position of the tipvane for measuring the tipvane angles.