lab project 2 report

i

Carl von Ossietzky University Oldenburg

Institute of Physics

Prof. Dr. Kühn

Dipl.-Ing. Andreas Schmidt

Development of a Small Wind Energy Converter for Rotor Power Experiments

– Report –

Name: OJOMA ABAMU

Studies: Engineering Physics

Semester: 6th Semester

Student ID: 2012527

E-Mail: [email protected]

ii

Abstract

In this project, a small wind turbine model was constructed with a variable speed and

pitch control in order to investigate the rotor power in different pitch angles. The main

idea was to design a small wind turbine model with the help of a Cp-λ curve, and the

rotor design, (with airfoil NACA 64-215) which is then used to carry out some

experiments. The structure of the wind turbine was designed with Autodesk Inventor,

and then a rapid prototype was created.

The small wind turbine model and all its components were mentioned with their

specifications and functions in addition to the description of the Inventor program.

The experiment will be carried out in a small, transportable wind tunnel. The small

wind turbine will be placed in the wind tunnel of about 10m/s wind speed. The wind

turbine starting from stand still, will accelerate a flywheel and therefore go through all

tip speed ratios between 0 and the maximum possible tip speed ratio.

The experiment will be repeated in different pitch angles, and the results will be

noted.

iii

Table of content Abstract .......................................................................................................................... ii

Table of Contents ......................................................... Error! Bookmark not defined.

Introduction .................................................................................................................... 5

1 Task of the Laboratory Experiment ........................................................................ 5

2 Dimensioning of the Fly Wheel .............................................................................. 6

2.1 First Approach ................................................................................................. 6

2.2 Experiment Setup ............................................................................................ 8

3 Rotor types ............................................................................................................ 10

3.1 Layout of the 3-bladed rotor geometry ......................................................... 11

3.1.1 Twist according to Betz: ........................................................................ 11

3.1.2 Chord Length according to Betz Equation............................................. 12

4 Friction measurement........................................................................................... 13

5 Measurement of the rotor power .......................................................................... 14

5.1 Genauigkeit ................................................................................................... 15

6 Friction compensation .......................................................................................... 15

7 Power measurement of the new designed rotor with three blades. ...................... 16

8 Design of the wind turbine ................................................................................... 17

8.1 Rotor .............................................................................................................. 18

8.2 Hub ................................................................................................................ 18

8.3 Tower, nacelle and foundation ...................................................................... 19

9 Small Wind Turbine Specifications ..................................................................... 19

10 Appendix: Tables of measurement values ........................................................... 20

iv

List of Abbreviations and Symbols

Symbol Meaning

Cp Power Coefficient

λ Tip Speed Ratio

ω Angular Velocity (Rads/s)

ρsteel Density for Steel

ρair Density for Air

λD Design tip Speed ratio

v Wind Speed

vrated Rated wind speed

R Rotor Radius

r Radius Points on Rotor

α Inflow Angle

αtwist Twist Angle

αA Angle of Attack

CL Lift coefficient

CD Drag coefficient

N Number of Blades

5

Introduction

Power from the wind has become an increasingly popular option for electricity generation.

Unlike traditional energy sources such as coal, oil, and gas that contribute large quantities of

carbon dioxide to the atmosphere, wind power relies on a non-polluting, renewable, ever-

present resource—the wind. In recent years, the cost of harnessing energy from the wind has

become more affordable making it a viable alternative for many communities.

A wind turbine generally consists of a two- or three-bladed propeller made of aluminium or

fiberglass mounted on the top of a tall tower. It converts energy from the mechanical energy

of moving air to electrical energy by means of a generator. The wind causes the shaft of the

turbine to spin which in turn causes a generator to produce electricity.

There are many reasons why there are usually three blades. The most important reason which

is based on physics is aerodynamic efficiency. As the number of blades increases, the

aerodynamic efficiency also increases. As a result of diminishing returns having more than

three blades leads to minimal improvements in aerodynamic efficiency.

1 Task of the Laboratory Experiment

The Power Coefficient CP tells how efficiently a turbine converts the energy in the wind to

electricity. Once the blade has been designed for optimum operation at a specific design tip

speed ratio (which is defined as the ratio between the blade tip speed and the wind speed), the

performance of the rotor over all expected tip speed ratios needs to be determined. For each

tip speed ratio, the aerodynamic conditions at each blade section need to be determined. From

these, the performance of the total rotor can be determined. The results are usually presented

as a graph of power coefficient (CP) versus the tip speed ratio (λ). This graph is called the CP-λ

curve.

After solving for the tip speed ratio (λ) in all the blade sections, we will then calculate for the

blade twist and chord length, which will be used for rapid prototyping of the rotor blade in

Autodesk Inventor. The rotor blade experiment will be carried out in a small wind tunnel with

wind speed of 10m/s, by means of a small Wind Turbine.

A Fly Wheel (a rotating mechanical device that is used to store rotational energy) will be

attached to the back of the small wind turbine, which will be used to measure the power

produced by the rotor at different tip speed ratios.

The diagram below is a descriptive sketch of how the wind turbine and the fly wheel will be

arranged. Flywheel and rotor are mounted on a shaft which is pivoted in the nacelle on the

tower top by means of two roller bearings. On the flat surface of the fly wheel is a mini

magnet. At the upper part of the Tower just before the nacelle, there is a platform which will

hold a sensor that will be used to measure the frequency gotten from the mini magnet during

rotation. This will be used to calculate the rotational speed of the rotor.

6

2 Dimensioning of the Fly Wheel

2.1 First Approach

At first, the dimensions of the fly wheel have to be calculated. In doing this, we will use the

help of the Cp-λ curve diagram below.

Figure 1: Power Coefficient Curve

The aim of a first dimensioning of the fly wheel is to have a time of at least 60 s up to 180 s

which the rotor needs from start-up to the maximum tip speed ratio of λ = 13.6. This time

space is not too long for experiments during exercises or lectures but long enough for precise

logging of the values. For a first approach, it is assumed, that the power coefficient is

constant at Cp= 0.25. Figure 1 shows this constant value (dashed-dotted line) in comparison

to a cP-λ-curve taken from the book from Gasch []. We use this to find the angular velocity.

, therefore

Where v= 10m/s , λ = 13.6 and R= 0.078m

ω= 1743.6 rad/s

We are trying to get a value for total Time which will range from 1-3 minutes. We Assume a

Mass (m) of 0.5kg and Length of 0.05m for the fly wheel, then solve to get a Moment mass

Inertia(I) of 0.00007965kg.m2.

Moment Mass Inertia is important because we need it to solve for the Kinetic Energy [Ekin =

Iω2 /2] of the flywheel. Now we have the Energy, we have to find a value for time that falls

7

within our range (1-3 minutes). Time = Energy/Power. After solving, we got a time of about

41 seconds which is far less that what we want, so we have to adjust our mass value in order

to get a much higher Moment mass Inertia. After several adjustments, we finalized on the

following values:

With

L= 0.07m D= 0.04m ρsteel= 7750kg/m3

Mass (m) = (Density) x (Area) x (Length)

= (7750kg/m3).(л).(0.040/4)2 m (0.070m)

= 0.682kg

Mass Moment Inertia

I = m.d2 /8

= (0.682kg).(0.040m)2 /8

= 0.0001364kg.m2

Energy

Ekin = ½ Iω2 We already have the value for ω above.

= (0.5) . (0.0001364 kgm2/s) . (1743.6 rad/s)2

= 207.338 Kgm2/s2

Finding the Power available in the wind, we use the formula

Pavail = ½ ρair.A.v3.Cp

where ρair = 1.225kg/m3, Cp= 0.25 r= 0.078m, A= л r2

Pavail = (0.5) . (1.225kg/m3). л . (0.078m)2 . (10m/s)3 . (0.25)

=2.93 Kg.m2/s3

Time = Energy/Power.

= 207.338 (kg.m2/s2) / 2.93 (kg.m2/s3)

= 70.76s.

8

The above intended dimensions of the flywheel turned out to be too big for the small wind

turbine. The weight of 691 g was found to be too heavy for the tower and for the bearings of

the rotor shaft. Therefore, the flywheel was dimensioned as follows:

length: 40 mm

diameter: 40 mm

This results in the following physical properties:

mass: 395 g

mass moment of inertia: 7.892 ∙ 10-5 kg∙m2

It was estimated, that these properties are a good compromise between a long acceleration

time of the flywheel on one hand and lower loads and especially friction in the bearings on

the other hand. The effect of the friction was compensated by means of a particular

measurement. This is described in detail below. A drawing of the flywheel is shown in

Figure2.

Figure 2: Drawing of the flywheel.

2.2 Experiment Setup

For the bearing of the rotor shaft, two roller bearings are used, that are designed for the axle

of a state-of-the-art cup anemometer of the type “Thies 1st Class”. The roller bearings are

mounted in the nacelle of the wind turbine. Behind the nacelle, a half-moon shaped washer is

mounted on the shaft which rotates in a light barrier. This allows measuring the rotating

frequency of the rotor. The flywheel is mounted at the end of the shaft. A photo of the turbine

is shown in Figure 3. The setup of the experiment is shown in Figure .

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Figure 3: Wind turbine for the experiment.

Figure 4: Setup of the experiment

flywheel

slotted washer

light

barrier

connection to

frequency

measurement

wind

tunnel

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3 Rotor types

The experiment was carried out with two different rotor types: the new designed rotor with three

blades, which is shown in Figure and a 2-bladed rotor which is shown in Figure 5. The existing rotor

was available from an existing wind turbine. It has a diameter of 150mm.

Figure 5: Photo of the 2-bladed rotor.

Figure 6: Photo of the 3-bladed rotor.

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3.1 Layout of the 3-bladed rotor geometry

3.1.1 Twist according to Betz:

Where R= 0.078m, λD= 4.95 αA = 12˚ (is gotten from the analysis of a NACA-64-

415 airfoil)

Therefore the twist of the rotor blade at different radius points in the blade is given in the

Table below:

Radius (r) m Twist Angle (α)˚

0.01 34.41

0.015 23.01

0.02 15.71

0.025 10.79

0.03 7.3

0.035 4.71

0.04 2.72

0.045 1.14

0.05 -0.13

0.055 -1.19

0.06 -2.07

0.065 -2.82

0.07 -3.47

0.075 -4.03

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Table 1

3.1.2 Chord Length according to Betz Equation

According to Betz equation, the value for chord lengths are given:

Table 2

0.078 -4.33

Radius (r) m Chord Length (t) m

0.01 0.0265

0.015 0.0185

0.02 0.0142

0.025 0.0115

0.03 0.0096

0.035 0.0083

0.04 0.0073

0.045 0.0065

0.05 0.0059

0.055 0.0054

0.06 0.0049

0.065 0.0046

0.07 0.0042

0.075 0.0040

0.078 0.0038

13

The above Table 2 shows the values of the chord length when you calculate it according to

Betz equation. The reality is that the blade tip is too tiny (3.8mm) like in the Figure 7 below

and would be very difficult for rapid prototyping, so we had to compromise on a design which

would be more convenient to create a prototype. It has the same twist angles but different

chord lengths like in the Figure 8 below.

Figure 7 Real Chord length according to Betzt

Figure 8 Compromised Chord length

4 Friction measurement

In order to compensate the friction of the bearing, a separate measurement has been carried

out. Therefore the rotor was removed from the turbine since the aerodynamic drag at the rotor

blades would influence the measurement. Then the shaft with the flywheel was accelerated by

means of a drilling machine. After loosening the connection to the drilling machine, the

rotational speed of the flywheel was measured until the friction had decelerated the flywheel

to stand still. The friction of the air has been neglected. For each time stamp ti [s] the rotational

frequency fi [Hz] and therefore the rotational frequency ωi [rad/s] was measured:

𝜔𝑖 = 2𝜋 ∙ 𝑓𝑖

Since the mass moment of inertia is known, for each value the kinetic energy of the flywheel

can be calculated:

𝑖 = 𝑛: 𝐸𝑘𝑖𝑛,𝑛 =1

2𝐼 ∙ 𝜔𝑛

2

And for the time step n+1 follows analogously:

𝑖 = 𝑛 + 1: 𝐸𝑘𝑖𝑛,(𝑛+1) =1

2𝐼 ∙ 𝜔(𝑛+1)

2

From value to value the change of energy ΔEkin can be calculated:

∆𝐸𝑘𝑖𝑛,𝑛 = 𝐸𝑘𝑖𝑛,(𝑛+1) − 𝐸𝑘𝑖𝑛,𝑛

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⇔ ∆𝐸𝑘𝑖𝑛,𝑛 =1

2𝐼 ∙ (𝜔(𝑛+1)

2 − 𝜔𝑛2)

This allows calculating the average power Pfric, which is converted by the friction for each

time step:

𝑃𝑓𝑟𝑖𝑐,𝑛 =Δ𝐸𝑘𝑖𝑛,𝑛Δ𝑡𝑛

The measurement of friction in the flywheel is shown in Table 3 in the appendix. Figure 9

shows a plot of the friction power over the rotational frequency. It can be seen, that the graph

is very volatile. For the compensation of the friction, the gliding average of the friction power

was used.

5 Measurement of the rotor power

For the measurement of the rotor power, the rotor was fixed at standstill while the speed of the

undisturbed wind speed was adjusted to 9.5 m/s. Then the rotor was unlocked and the

acceleration of the flywheel was measured. Analogous to the procedure for the friction

measurement, from value to value the change of energy ΔEkin can be calculated with:

∆𝐸𝑘𝑖𝑛,𝑛 = 𝐸𝑘𝑖𝑛,(𝑛+1) − 𝐸𝑘𝑖𝑛,𝑛

⇔ ∆𝐸𝑘𝑖𝑛,𝑛 =1

2𝐼 ∙ (𝜔(𝑛+1)

2 − 𝜔𝑛2)

Figure 9: Plot of the friction power over the rotational frequency.

15

Since the rotor has a very low mass, its moment of inertia is neglected. The average power,

which was delivered by the rotor in the time step is:

𝑃𝑛 =Δ𝐸𝑘𝑖𝑛,𝑛Δ𝑡𝑛

By means of the power, the power coefficient cP,n can be calculated for each time step. The

results of the measurement are shown in Figure and in the appendix in Table .

.

5.1 Genauigkeit

6 Friction compensation

In order to compensate the effect of the friction, at each time step, the measured friction

power had to be added to the power which was delivered for the acceleration of the fly wheel.

Since the rotational speeds in the time steps of Table do not fit to the rotational speeds of the

rows in Table , they had to be fitted by linear interpolation. The result is shown in Table .

A plot of the corrected curve of the dimensionless power coefficient is shown in Figure . It

shows that the influence of the friction is very strong.

The shape of the graph shows a very unsteady behaviour. Especially in the range of the tip

speed ratio between 4 and 5 the graph shows a staggered development which cannot be

explained. It is not clear, whether the experiment was strongly influenced by side effects or

whether the measurement method led to deviations, but it is presumed that both happened.

Figure 10: Power measurement of the 2-bladed rotor.

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7 Power measurement of the new designed rotor with three blades.

The measurement procedure was repeated with the new designed, 3-bladed rotor. Figure

shows a photo of this rotor. The results are shown in Table 6. Table 77 shows the values of the

correction of the friction effect. The graph both of the uncorrected as well as the corrected

measurement is depicted in Figure 2.

Like the measurement of the 2-bladed rotor, also this measurement shows unsteady behaviour

due to side effects and measurement errors. The most important thing is that the values of the

power coefficients are very low. Therefore, the friction power is representing a high amount

of the total power of the rotor. The highest value is reached at a tip speed ratio of 3.3. The

power coefficient is 5.8% at this point, which is only one tenth of the theoretic maximum of

59% according to Betz. The measurement shows also, that the behaviour of the rotor deviates

massively from the behaviour which was intended by the layout. The tip speed ratio is much

lower than calculated. The reason could be that the used profiles are not suitable for a scaling

to the small dimensions of the wind turbine. For the scaling not only the tip speed ratio is

relevant but- in regard of the profiles- also the so called Reynolds number. It describes the

characteristics of the flow around the rotor blade. Figure shows a comparison of the 3-bladed

rotor with the 2-bladed rotor, which shows again the completely different behaviour of the

rotor.

Figure 11: Dimensionless power curve of the 2-bladed rotor with correction of the friction coefficient.

17

8 Design of the wind turbine

Figure 12: Graph of the dimensionless power measurement of the 3-bladed rotor.

Figure 13: Comparison of the 3-bladed and the 2-bladed rotor.

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8.1 Rotor

With the help of Autodesk Inventor, and the dimensions derived from the twist angle and

chord length, we were able to design the shape of the rotor blade. Since we are going to make

the experiments in different pitch angles, the root of the blade is modified to be cone-like.

This allows easy pitching of the blade, and it also prevents loss of the blade due to the high

rotation speed,

Figure 14 Modified Rotor blade

8.2 Hub

The hub is designed in such a way that it can hold the rotor blades firmly. It is made up of two

identical spheres which will be glued together. It has a cone-like cavity that fits the blades

firmly and also allows pitching of the blades.

Figure 15 Modified Hub

The purpose of pitch control is to maintain the optimum blade angle to achieve certain rotor

speeds or power output. Increasing the pitch angle at a certain degrees will result in the

decrease in power coefficient, therefore decrease in power. In figure 16, you can see how the

Cp-λ curve is influenced by different pitch angles.

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Figure 16 Influence of pitching on the Cp-λ curve

8.3 Tower, nacelle and foundation

The tower, nacelle and foundation are designed together as one piece such that you do not

need to attach any part. The tower is a hollow cylinder which is 170mm high. The nacelle is a

cuboid which has round hollows on both ends. This is to make place for the roller bearings

and shaft. The foundation is just a flat plate, which will be screwed to a stable surface during

the experiment.

Figure 17 Sketch of Nacelle and foundation (left) and one-piece tower (right)

9 Small Wind Turbine Specifications

Rotor:

Rotor Diameter 0.156m

Hub Diameter 0.020m

Hub Height 0.180m

Number of Blades 3

Blades:

3-Bladed Span 0.078m 2-Bladed Span 0.075mm

Blade Chord 0.016m

Nacelle:

Length 0.030m

Width 0.018m

20

Height 0.018m

Tower:

Height 0.165m

Diameter 0.012m

Foundation:

Length 0.040m

Width 0.040m

Height 0.005m

10 Appendix: Tables of measurement values

Table 3: Measurement of friction in the flywheel.

time stamp [s]

rot. frequency [Hz]

ω [rad/s] ΔEkin = ½ I(ω2n+1-

ω2n) [J]

Pfric = ΔEkin / Δt

[W]

Pfric [W]

gliding

average

0 186.94 1174.552

1 184.09 1156.668 -1.645 1.645

2 181.05 1137.546 -1.731 1.731 1.663

3 178.16 1119.431 -1.613 1.613 1.624

4 175.39 1101.991 -1.529 1.529 1.445

5 173.19 1088.186 -1.193 1.193 1.439

6 170.21 1069.464 -1.594 1.594 1.432

7 167.34 1051.443 -1.508 1.508 1.533

8 164.45 1033.245 -1.497 1.497 1.362

9 162.32 1019.915 -1.080 1.080 1.310

10 159.62 1002.948 -1.354 1.354 1.282

11 156.76 984.934 -1.413 1.413 1.330

12 154.23 969.072 -1.223 1.223 1.295

13 151.61 952.599 -1.249 1.249 1.260

14 148.81 935.025 -1.309 1.309 1.245

15 146.25 918.946 -1.176 1.176 1.178

16 143.93 904.369 -1.049 1.049 1.094

17 141.56 889.443 -1.056 1.056 1.052

18 139.16 874.358 -1.050 1.050 1.090

19 136.45 857.326 -1.164 1.164 1.047

20 134.25 843.489 -0.929 0.929 1.029

21 131.84 828.398 -0.996 0.996 1.018

22 129.06 810.932 -1.130 1.130 0.968

23 127.11 798.675 -0.778 0.778 0.941

24 124.78 784.013 -0.916 0.916 0.908

25 122.10 767.165 -1.031 1.031 0.947

26 119.72 752.238 -0.895 0.895 0.885

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time stamp [s]

rot. frequency [Hz]


ω2n) [J]


[W]

Pfric [W]

gliding

average

27 117.75 739.851 -0.729 0.729 0.847

28 115.23 724.002 -0.915 0.915 0.790

29 113.19 711.182 -0.726 0.726 0.816

30 110.87 696.637 -0.808 0.808 0.742

31 108.85 683.922 -0.693 0.693 0.771

32 106.43 668.706 -0.812 0.812 0.736

33 104.28 655.240 -0.703 0.703 0.726

34 102.22 642.280 -0.664 0.664 0.696

35 99.93 627.910 -0.720 0.720 0.646

36 98.14 616.631 -0.554 0.554 0.659

37 95.81 602.011 -0.703 0.703 0.616

38 93.82 589.457 -0.590 0.590 0.613

39 91.92 577.578 -0.547 0.547 0.585

40 89.75 563.892 -0.616 0.616 0.559

41 87.89 552.227 -0.514 0.514 0.561

42 85.85 539.406 -0.552 0.552 0.523

43 83.95 527.474 -0.502 0.502 0.514

44 82.06 515.620 -0.488 0.488 0.476

45 80.33 504.743 -0.438 0.438 0.478

46 78.27 491.808 -0.509 0.509 0.450

47 76.61 481.327 -0.402 0.402 0.463

48 74.58 468.608 -0.477 0.477 0.384

49 73.40 461.186 -0.272 0.272 0.400

50 71.40 448.619 -0.451 0.451 0.387

51 69.40 436.053 -0.439 0.439 0.411

52 67.80 426.000 -0.342 0.342 0.392

53 65.90 414.062 -0.396 0.396 0.354

54 64.30 404.009 -0.325 0.325 0.372

55 62.30 391.442 -0.394 0.394 0.342

56 60.70 381.389 -0.307 0.307 0.321

57 59.30 372.593 -0.262 0.262 0.299

58 57.50 361.283 -0.328 0.328 0.285

59 56.00 351.858 -0.265 0.265 0.289

60 54.40 341.805 -0.275 0.275 0.258

61 53.00 333.009 -0.234 0.234 0.235

62 51.80 325.469 -0.196 0.196 0.231

63 50.14 315.039 -0.264 0.264 0.233

64 48.58 305.237 -0.240 0.240 0.234

65 47.26 296.943 -0.197 0.197 0.210

66 45.92 288.524 -0.195 0.195 0.199

67 44.46 279.350 -0.206 0.206 0.189

68 43.23 271.622 -0.168 0.168 0.190

69 41.74 262.260 -0.197 0.197 0.177

22

time stamp [s]

rot. frequency [Hz]


ω2n) [J]


[W]

Pfric [W]

gliding

average

70 40.45 254.155 -0.165 0.165 0.175

71 39.13 245.861 -0.164 0.164 0.161

72 37.84 237.756 -0.155 0.155 0.152

73 36.65 230.279 -0.138 0.138 0.143

74 35.43 222.613 -0.137 0.137 0.137

75 34.17 214.696 -0.137 0.137 0.136

76 32.89 206.654 -0.134 0.134 0.125

77 31.84 200.057 -0.106 0.106 0.124

78 30.48 191.511 -0.132 0.132 0.117

79 29.25 183.783 -0.114 0.114 0.121

80 27.95 175.615 -0.116 0.116 0.107

81 26.89 168.955 -0.091 0.091 0.106

82 25.54 160.473 -0.110 0.110 0.093

83 24.54 154.189 -0.078 0.078 0.091

84 23.42 147.152 -0.084 0.084 0.077

85 22.43 140.932 -0.071 0.071 0.076

86 21.37 134.272 -0.072 0.072 0.067

87 20.49 128.742 -0.057 0.057 0.062

88 19.61 123.213 -0.055 0.055 0.055

89 18.72 117.621 -0.053 0.053 0.050

90 17.98 112.972 -0.042 0.042 0.049

91 17.05 107.128 -0.051 0.051 0.044

92 16.29 102.353 -0.039 0.039 0.043

93 15.51 97.452 -0.039 0.039 0.037

94 14.84 93.242 -0.032 0.032 0.035

95 14.09 88.530 -0.034 0.034 0.033

96 13.31 83.629 -0.033 0.033 0.031

97 12.67 79.608 -0.026 0.026 0.028

98 12.01 75.461 -0.025 0.025 0.025

99 11.33 71.188 -0.025 0.025 0.025

100 10.63 66.790 -0.024 0.024 0.022

101 10.09 63.397 -0.017 0.017 0.019

102 9.54 59.942 -0.017 0.017 0.017

103 8.97 56.360 -0.016 0.016 0.016

104 8.38 52.653 -0.016 0.016 0.016

105 7.77 48.820 -0.015 0.015 0.015

106 7.16 44.988 -0.014 0.014 0.013

107 6.72 42.223 -0.010 0.010 0.011

108 6.24 39.207 -0.010 0.010 0.009

109 5.75 36.128 -0.009 0.009 0.009

110 5.23 32.861 -0.009 0.009 0.008

23

time stamp [s]

rot. frequency [Hz]


ω2n) [J]


[W]

Pfric [W]

gliding

average

111 4.88 30.675 -0.005 0.005 0.008

112 4.31 27.087 -0.008 0.008 0.006

113 3.90 24.511 -0.005 0.005 0.005

114 3.69 23.179 -0.003 0.003 0.004

115 3.23 20.288 -0.005 0.005 0.003

116 2.98 18.736 -0.002 0.002 0.004

117 2.44 15.312 -0.005 0.005 0.003

118 2.13 13.358 -0.002 0.002 0.003

119 1.78 11.203 -0.002 0.002 0.001

120 1.78 11.203 0.000 0.000 0.001

121 1.36 8.526 -0.002 0.002 0.001

122 1.36 8.526 0.000 0.000 0.001

123 0.72 4.530 -0.002 0.002 0.001

124 0.72 4.530 0.000 0.000 0.001

125 0.72 4.530 0.000 0.000 0.000

126 0.72 4.530 0.000 0.000 0.000

127 0.00 0.000 -0.001 0.001 0.000

128 0.00 0.000 0.000 0.000 0.000

129 0.00 0.000 0.000 0.000 0.000

Table 4: Power measurement of the 2-bladed rotor.

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-

ω2n) [J]

P = ΔEkin /

Δt [W]

cP [-]

0 0.000 0 0 0 0 0 0

1 0.000 0.000 0.000 0.000 0.00E+00 0.00E+00 0.00E+00

2 0.000 0.000 0.000 0.000 0.00E+00 0.00E+00 0.00E+00

3 0.000 0.000 0.000 0.000 0.00E+00 0.00E+00 0.00E+00

4 2.033 12.774 0.958 0.101 6.44E-03 6.44E-03 6.94E-04

5 4.198 26.377 1.978 0.208 2.10E-02 2.10E-02 2.26E-03

6 5.990 37.636 2.823 0.297 2.84E-02 2.84E-02 3.06E-03

7 7.290 45.804 3.435 0.362 2.69E-02 2.69E-02 2.90E-03

8 8.770 55.104 4.133 0.435 3.70E-02 3.70E-02 3.99E-03

9 10.090 63.397 4.755 0.501 3.88E-02 3.88E-02 4.18E-03

10 11.610 72.948 5.471 0.576 5.14E-02 5.14E-02 5.54E-03

11 13.030 81.870 6.140 0.646 5.45E-02 5.45E-02 5.87E-03

12 14.320 89.975 6.748 0.710 5.50E-02 5.50E-02 5.92E-03

13 16.020 100.657 7.549 0.795 8.03E-02 8.03E-02 8.66E-03

14 17.610 110.647 8.299 0.874 8.33E-02 8.33E-02 8.98E-03

15 19.600 123.150 9.236 0.972 1.15E-01 1.15E-01 1.24E-02

16 21.620 135.842 10.188

1.072 1.30E-01 1.30E-01 1.40E-02

24

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-

ω2n) [J]

P = ΔEkin /

Δt [W]

cP [-]

17 23.810 149.603 11.220

1.181 1.55E-01 1.55E-01 1.67E-02

18 26.390 165.813 12.436

1.309 2.02E-01 2.02E-01 2.17E-02

19 29.170 183.281 13.746

1.447 2.41E-01 2.41E-01 2.59E-02

20 31.510 197.983 14.849

1.563 2.21E-01 2.21E-01 2.38E-02

21 34.710 218.089 16.357

1.722 3.30E-01 3.30E-01 3.56E-02

22 37.930 238.321 17.874

1.881 3.64E-01 3.64E-01 3.93E-02

23 42.500 267.035 20.028

2.108 5.73E-01 5.73E-01 6.17E-02

24 46.440 291.791 21.884

2.304 5.46E-01 5.46E-01 5.88E-02

25 51.800 325.469 24.410

2.569 8.20E-01 8.20E-01 8.84E-02

26 57.100 358.770 26.908

2.832 8.99E-01 8.99E-01 9.69E-02

27 62.500 392.699 29.452

3.100 1.01E+00 1.01E+00 1.08E-01

28 67.800 426.000 31.950

3.363 1.08E+00 1.08E+00 1.16E-01

29 73.600 462.442 34.683

3.651 1.28E+00 1.28E+00 1.38E-01

30 78.600 493.858 37.039

3.899 1.19E+00 1.19E+00 1.28E-01

31 82.500 518.363 38.877

4.092 9.79E-01 9.79E-01 1.05E-01

32 85.500 537.212 40.291

4.241 7.85E-01 7.85E-01 8.46E-02

33 89.300 561.088 42.082

4.430 1.03E+00 1.03E+00 1.12E-01

34 92.400 580.566 43.542

4.583 8.77E-01 8.77E-01 9.46E-02

35 94.400 593.133 44.485

4.683 5.82E-01 5.82E-01 6.27E-02

36 96.500 606.327 45.475

4.787 6.24E-01 6.24E-01 6.73E-02

37 98.300 617.637 46.323

4.876 5.46E-01 5.46E-01 5.89E-02

38 99.600 625.805 46.935

4.941 4.01E-01 4.01E-01 4.32E-02

25

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-

ω2n) [J]

P = ΔEkin /

Δt [W]

cP [-]

39 100.900 633.973 47.548

5.005 4.06E-01 4.06E-01 4.38E-02

40 102.000 640.885 48.066

5.060 3.48E-01 3.48E-01 3.75E-02

41 102.800 645.911 48.443

5.099 2.55E-01 2.55E-01 2.75E-02

42 103.600 650.938 48.820

5.139 2.57E-01 2.57E-01 2.77E-02

43 104.200 654.708 49.103

5.169 1.94E-01 1.94E-01 2.09E-02

44 104.700 657.850 49.339

5.194 1.63E-01 1.63E-01 1.75E-02

45 105.100 660.363 49.527

5.213 1.31E-01 1.31E-01 1.41E-02

46 105.400 662.248 49.669

5.228 9.84E-02 9.84E-02 1.06E-02

47 105.800 664.761 49.857

5.248 1.32E-01 1.32E-01 1.42E-02

48 106.100 666.646 49.998

5.263 9.90E-02 9.90E-02 1.07E-02

49 106.500 669.159 50.187

5.283 1.32E-01 1.32E-01 1.43E-02

50 106.800 671.044 50.328

5.298 9.97E-02 9.97E-02 1.07E-02

51 107.100 672.929 50.470

5.313 1.00E-01 1.00E-01 1.08E-02

52 107.300 674.186 50.564

5.323 6.68E-02 6.68E-02 7.20E-03

53 107.500 675.442 50.658

5.332 6.69E-02 6.69E-02 7.21E-03

54 107.800 677.327 50.800

5.347 1.01E-01 1.01E-01 1.08E-02

55 108.000 678.584 50.894

5.357 6.72E-02 6.72E-02 7.24E-03

56 108.300 680.469 51.035

5.372 1.01E-01 1.01E-01 1.09E-02

57 108.400 681.097 51.082

5.377 3.38E-02 3.38E-02 3.64E-03

58 108.600 682.354 51.177

5.387 6.76E-02 6.76E-02 7.29E-03

59 108.700 682.982 51.224

5.392 3.39E-02 3.39E-02 3.65E-03

60 108.700 682.982 51.224

5.392 0.00E+00 0.00E+00 0.00E+00

26

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-

ω2n) [J]

P = ΔEkin /

Δt [W]

cP [-]

61 108.700 682.982 51.224

5.392 0.00E+00 0.00E+00 0.00E+00

62 108.800 683.611 51.271

5.397 3.39E-02 3.39E-02 3.65E-03

63 108.900 684.239 51.318

5.402 3.39E-02 3.39E-02 3.65E-03

64 108.800 683.611 51.271

5.397 -3.39E-02 -3.39E-02 -3.65E-03

65 108.900 684.239 51.318

5.402 3.39E-02 3.39E-02 3.65E-03

66 108.900 684.239 51.318

5.402 0.00E+00 0.00E+00 0.00E+00

67 108.800 683.611 51.271

5.397 -3.39E-02 -3.39E-02 -3.65E-03

68 108.900 684.239 51.318

5.402 3.39E-02 3.39E-02 3.65E-03

69 108.800 683.611 51.271

5.397 -3.39E-02 -3.39E-02 -3.65E-03

70 109.000 684.867 51.365

5.407 6.79E-02 6.79E-02 7.31E-03

71 109.100 685.496 51.412

5.412 3.40E-02 3.40E-02 3.66E-03

72 109.300 686.752 51.506

5.422 6.80E-02 6.80E-02 7.33E-03

73 109.400 687.380 51.554

5.427 3.41E-02 3.41E-02 3.67E-03

74 109.600 688.637 51.648

5.437 6.82E-02 6.82E-02 7.35E-03

75 109.700 689.265 51.695

5.442 3.42E-02 3.42E-02 3.68E-03

76 109.800 689.894 51.742

5.447 3.42E-02 3.42E-02 3.68E-03

77 110.000 691.150 51.836

5.456 6.85E-02 6.85E-02 7.38E-03

78 110.200 692.407 51.931

5.466 6.86E-02 6.86E-02 7.39E-03

79 110.300 693.035 51.978

5.471 3.43E-02 3.43E-02 3.70E-03

80 110.300 693.035 51.978

5.471 0.00E+00 0.00E+00 0.00E+00

81 110.300 693.035 51.978

5.471 0.00E+00 0.00E+00 0.00E+00

82 110.300 693.035 51.978

5.471 0.00E+00 0.00E+00 0.00E+00

27

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-

ω2n) [J]

P = ΔEkin /

Δt [W]

cP [-]

83 110.300 693.035 51.978

5.471 0.00E+00 0.00E+00 0.00E+00

Table 5: Correction of the friction effect for the measurement of the 2-bladed rotor.

Friction measurement, lin. interpol. Rotor measurement

rot. frequency [Hz] λ [-] Pmeasurement Pfric. lin. interpol. Pcorrected cP-corrected [-]

0.000 0.00 0.00 0.000 0.000 0.00E+00

0.000 0.00 0.00 0.000 0.000 0.00E+00

0.000 0.00 0.00 0.000 0.000 0.00E+00

2.033 0.10 0.01 0.003 0.009 1.01E-03

4.198 0.21 0.02 0.009 0.030 3.19E-03

5.990 0.30 0.03 0.014 0.042 4.56E-03

7.290 0.36 0.03 0.021 0.048 5.14E-03

8.770 0.44 0.04 0.046 0.083 8.90E-03

10.090 0.50 0.04 0.010 0.049 5.26E-03

11.610 0.58 0.05 -0.014 0.037 4.04E-03

13.030 0.65 0.05 0.018 0.073 7.81E-03

14.320 0.71 0.05 0.017 0.072 7.72E-03

16.020 0.79 0.08 0.035 0.115 1.24E-02

17.610 0.87 0.08 0.036 0.119 1.28E-02

19.600 0.97 0.12 0.070 0.185 2.00E-02

21.620 1.07 0.13 0.056 0.186 2.00E-02

23.810 1.18 0.15 0.089 0.244 2.63E-02

26.390 1.31 0.20 0.101 0.303 3.26E-02

29.170 1.45 0.24 0.120 0.361 3.88E-02

31.510 1.56 0.22 0.122 0.344 3.70E-02

34.710 1.72 0.33 0.136 0.466 5.03E-02

37.930 1.88 0.36 0.153 0.517 5.57E-02

42.500 2.11 0.57 0.184 0.756 8.15E-02

46.440 2.30 0.55 0.203 0.749 8.07E-02

51.800 2.57 0.82 0.231 1.052 1.13E-01

57.100 2.83 0.90 0.286 1.185 1.28E-01

62.500 3.10 1.01 0.345 1.351 1.46E-01

67.800 3.36 1.08 0.392 1.468 1.58E-01

73.600 3.65 1.28 0.397 1.675 1.80E-01

78.600 3.90 1.19 0.454 1.640 1.77E-01

82.500 4.09 0.98 0.485 1.464 1.58E-01

85.500 4.24 0.79 0.521 1.306 1.41E-01

89.300 4.43 1.03 0.559 1.594 1.72E-01

28



92.400 4.58 0.88 0.592 1.469 1.58E-01

94.400 4.68 0.58 0.614 1.196 1.29E-01

96.500 4.79 0.62 0.628 1.253 1.35E-01

98.300 4.88 0.55 0.658 1.204 1.30E-01

99.600 4.94 0.40 0.648 1.049 1.13E-01

100.900 5.01 0.41 0.667 1.073 1.16E-01

102.000 5.06 0.35 0.691 1.039 1.12E-01

102.800 5.10 0.26 0.704 0.960 1.03E-01

103.600 5.14 0.26 0.716 0.973 1.05E-01

104.200 5.17 0.19 0.725 0.919 9.91E-02

104.700 5.19 0.16 0.728 0.891 9.60E-02

105.100 5.21 0.13 0.730 0.861 9.28E-02

105.400 5.23 0.10 0.731 0.830 8.94E-02

105.800 5.25 0.13 0.733 0.865 9.32E-02

106.100 5.26 0.10 0.735 0.834 8.98E-02

106.500 5.28 0.13 0.737 0.870 9.37E-02

106.800 5.30 0.10 0.741 0.841 9.06E-02

107.100 5.31 0.10 0.746 0.846 9.11E-02

107.300 5.32 0.07 0.749 0.815 8.79E-02

107.500 5.33 0.07 0.751 0.818 8.82E-02

107.800 5.35 0.10 0.756 0.856 9.23E-02

108.000 5.36 0.07 0.759 0.826 8.90E-02

108.300 5.37 0.10 0.763 0.864 9.31E-02

108.400 5.38 0.03 0.764 0.798 8.60E-02

108.600 5.39 0.07 0.767 0.835 9.00E-02

108.700 5.39 0.03 0.769 0.803 8.65E-02

108.700 5.39 0.00 0.769 0.769 8.28E-02

108.700 5.39 0.00 0.769 0.769 8.28E-02

108.800 5.40 0.03 0.770 0.804 8.66E-02

108.900 5.40 0.03 0.770 0.804 8.66E-02

108.800 5.40 -0.03 0.770 0.736 7.93E-02

108.900 5.40 0.03 0.770 0.804 8.66E-02

108.900 5.40 0.00 0.770 0.770 8.30E-02

108.800 5.40 -0.03 0.772 0.738 7.95E-02

108.900 5.40 0.03 0.770 0.804 8.66E-02

108.800 5.40 -0.03 0.772 0.738 7.95E-02

109.000 5.41 0.07 0.769 0.837 9.02E-02

109.100 5.41 0.03 0.767 0.801 8.64E-02

109.300 5.42 0.07 0.765 0.833 8.97E-02

109.400 5.43 0.03 0.763 0.797 8.59E-02

109.600 5.44 0.07 0.760 0.828 8.93E-02

29



109.700 5.44 0.03 0.759 0.793 8.55E-02

109.800 5.45 0.03 0.757 0.792 8.53E-02

110.000 5.46 0.07 0.755 0.823 8.87E-02

110.200 5.47 0.07 0.752 0.820 8.84E-02

110.300 5.47 0.03 0.750 0.785 8.46E-02

110.300 5.47 0.00 0.750 0.750 8.09E-02

110.300 5.47 0.00 0.750 0.750 8.09E-02

110.300 5.47 0.00 0.750 0.750 8.09E-02

110.300 5.47 0.00 0.750 0.750 8.09E-02

Table 6: Results of the power measurement of the 3-bladed rotor.

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-ω2

n) [J]

P = ΔEkin / Δt

[W]

cP [-]

20 0.0 0.0 0.0 0.00 0 0 0

22 0.7 4.7 0.4 0.04 8.65E-04 4.32E-04 3.99E-05

24 3.8 23.8 1.9 0.20 2.15E-02 1.08E-02 9.95E-04

26 5.7 35.9 2.9 0.31 2.86E-02 1.43E-02 1.32E-03

28 7.3 46.1 3.7 0.39 3.30E-02 1.65E-02 1.52E-03

30 8.7 54.9 4.4 0.47 3.51E-02 1.75E-02 1.62E-03

32 9.7 61.2 5.0 0.52 2.88E-02 1.44E-02 1.33E-03

34 10.9 68.3 5.5 0.58 3.63E-02 1.81E-02 1.68E-03

36 12.0 75.3 6.1 0.64 3.95E-02 1.98E-02 1.83E-03

38 13.0 81.7 6.6 0.70 4.01E-02 2.00E-02 1.85E-03

40 14.2 89.1 7.2 0.76 4.96E-02 2.48E-02 2.29E-03

42 15.6 97.9 7.9 0.83 6.49E-02 3.25E-02 3.00E-03

44 17.0 106.9 8.7 0.91 7.26E-02 3.63E-02 3.35E-03

46 18.6 116.9 9.5 1.00 8.82E-02 4.41E-02 4.07E-03

30

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-ω2

n) [J]

P = ΔEkin / Δt

[W]

cP [-]

48 20.3 127.3 10.3 1.09 1.00E-01 5.02E-02 4.64E-03

50 21.8 136.8 11.1 1.17 9.89E-02 4.94E-02 4.57E-03

52 23.5 147.8 12.0 1.26 1.23E-01 6.17E-02 5.70E-03

54 25.1 157.8 12.8 1.35 1.20E-01 6.02E-02 5.56E-03

56 26.7 167.7 13.6 1.43 1.27E-01 6.37E-02 5.89E-03

58 28.8 181.0 14.7 1.54 1.83E-01 9.16E-02 8.47E-03

60 30.8 193.7 15.7 1.65 1.88E-01 9.38E-02 8.67E-03

62 33.4 209.9 17.0 1.79 2.58E-01 1.29E-01 1.19E-02

64 35.8 224.6 18.2 1.92 2.52E-01 1.26E-01 1.16E-02

66 38.6 242.8 19.7 2.07 3.35E-01 1.67E-01 1.55E-02

68 41.7 261.8 21.2 2.23 3.78E-01 1.89E-01 1.74E-02

70 45.1 283.1 22.9 2.41 4.59E-01 2.30E-01 2.12E-02

72 48.2 302.7 24.5 2.58 4.52E-01 2.26E-01 2.09E-02

74 52.3 328.6 26.6 2.80 6.46E-01 3.23E-01 2.99E-02

76 55.9 351.2 28.4 2.99 6.07E-01 3.03E-01 2.80E-02

78 59.2 372.0 30.1 3.17 5.92E-01 2.96E-01 2.73E-02

80 62.2 390.8 31.7 3.33 5.67E-01 2.84E-01 2.62E-02

82 64.7 406.5 32.9 3.47 4.94E-01 2.47E-01 2.28E-02

84 66.6 418.5 33.9 3.57 3.89E-01 1.94E-01 1.80E-02

86 68.0 427.3 34.6 3.64 2.94E-01 1.47E-01 1.36E-02

88 69.0 433.5 35.1 3.70 2.13E-01 1.07E-01 9.86E-03

90 69.7 437.9 35.5 3.73 1.51E-01 7.56E-02 6.99E-03

31

time stamp [s]

rot. frequency [Hz]

ω [rad/s]

vtip [m/s]

λ [-] ΔEkin = ½

I(ω2n+1-ω2

n) [J]

P = ΔEkin / Δt

[W]

cP [-]

92 70.1 440.5 35.7 3.76 8.71E-02 4.36E-02 4.02E-03

94 70.4 442.3 35.8 3.77 6.57E-02 3.28E-02 3.03E-03

96 70.7 444.2 36.0 3.79 6.59E-02 3.30E-02 3.05E-03

98 70.9 445.5 36.1 3.80 4.41E-02 2.21E-02 2.04E-03

100 71.1 446.7 36.2 3.81 4.42E-02 2.21E-02 2.04E-03

102 71.2 447.4 36.2 3.81 2.22E-02 1.11E-02 1.02E-03

104 71.3 448.0 36.3 3.82 2.22E-02 1.11E-02 1.03E-03

106 71.3 448.0 36.3 3.82 0.00E+00 0.00E+00 0.00E+00

108 71.3 448.0 36.3 3.82 0.00E+00 0.00E+00 0.00E+00

110 71.4 448.6 36.3 3.83 2.22E-02 1.11E-02 1.03E-03

112 71.5 449.2 36.4 3.83 2.23E-02 1.11E-02 1.03E-03

114 71.5 449.2 36.4 3.83 0.00E+00 0.00E+00 0.00E+00

116 71.6 449.9 36.4 3.84 2.23E-02 1.11E-02 1.03E-03

118 71.6 449.9 36.4 3.84 0.00E+00 0.00E+00 0.00E+00

120 71.6 449.9 36.4 3.84 0.00E+00 0.00E+00 0.00E+00

122 71.6 449.9 36.4 3.84 0.00E+00 0.00E+00 0.00E+00

124 71.7 450.5 36.5 3.84 2.23E-02 1.12E-02 1.03E-03

126 71.7 450.5 36.5 3.84 0.00E+00 0.00E+00 0.00E+00

Table 7: Correction of the friction effect for the 3-bladed rotor.

Rotor measurement Friction measurement

32

rot. frequency [Hz] λ [-] Pmeasurement [W] Pfric. lin. interpol. [W] Pcorrected [W] cP-corrected [-]

0.7 0.0 0.00 0.001 0.001 1.06E-04

3.8 0.2 0.01 0.005 0.016 1.43E-03

5.7 0.3 0.01 0.009 0.023 2.17E-03

7.3 0.4 0.02 0.014 0.030 2.78E-03

8.7 0.5 0.02 0.016 0.034 3.12E-03

9.7 0.5 0.01 0.018 0.032 2.97E-03

10.9 0.6 0.02 0.023 0.041 3.80E-03

12.0 0.6 0.02 0.025 0.045 4.16E-03

13.0 0.7 0.02 0.030 0.050 4.59E-03

14.2 0.8 0.02 0.033 0.058 5.35E-03

15.6 0.8 0.03 0.037 0.070 6.43E-03

17.0 0.9 0.04 0.044 0.080 7.43E-03

18.6 1.0 0.04 0.050 0.094 8.69E-03

20.3 1.1 0.05 0.060 0.110 1.02E-02

21.8 1.2 0.05 0.070 0.120 1.10E-02

23.5 1.3 0.06 0.079 0.140 1.30E-02

25.1 1.3 0.06 0.092 0.152 1.41E-02

26.7 1.4 0.06 0.104 0.167 1.55E-02

28.8 1.5 0.09 0.116 0.208 1.92E-02

30.8 1.7 0.09 0.119 0.213 1.97E-02

33.4 1.8 0.13 0.130 0.259 2.39E-02

35.8 1.9 0.13 0.139 0.265 2.45E-02

38.6 2.1 0.17 0.158 0.325 3.00E-02

41.7 2.2 0.19 0.177 0.366 3.38E-02

45.1 2.4 0.23 0.193 0.423 3.91E-02

48.2 2.6 0.23 0.226 0.452 4.18E-02

52.3 2.8 0.32 0.233 0.556 5.14E-02

55.9 3.0 0.30 0.287 0.591 5.46E-02

59.2 3.2 0.30 0.298 0.594 5.48E-02

62.2 3.3 0.28 0.341 0.624 5.77E-02

64.7 3.5 0.25 0.367 0.614 5.68E-02

66.6 3.6 0.19 0.368 0.562 5.20E-02

68.0 3.6 0.15 0.394 0.541 5.00E-02

69.0 3.7 0.11 0.406 0.513 4.74E-02

69.7 3.7 0.08 0.407 0.483 4.46E-02

70.1 3.8 0.04 0.402 0.446 4.12E-02

70.4 3.8 0.03 0.399 0.432 3.99E-02

70.7 3.8 0.03 0.395 0.428 3.96E-02

70.9 3.8 0.02 0.393 0.415 3.84E-02

71.1 3.8 0.02 0.391 0.413 3.82E-02

71.2 3.8 0.01 0.390 0.401 3.70E-02

33

Rotor measurement Friction measurement

rot. frequency [Hz] λ [-] Pmeasurement [W] Pfric. lin. interpol. [W] Pcorrected [W] cP-corrected [-]

71.3 3.8 0.01 0.389 0.400 3.69E-02

71.3 3.8 0.00 0.389 0.389 3.59E-02

71.3 3.8 0.00 0.389 0.389 3.59E-02

71.4 3.8 0.01 0.387 0.398 3.68E-02

71.5 3.8 0.01 0.388 0.399 3.69E-02

71.5 3.8 0.00 0.388 0.388 3.58E-02

71.6 3.8 0.01 0.389 0.400 3.69E-02

71.6 3.8 0.00 0.389 0.389 3.59E-02

71.6 3.8 0.00 0.389 0.389 3.59E-02

71.6 3.8 0.00 0.389 0.389 3.59E-02

71.7 3.8 0.01 0.389 0.400 3.70E-02

71.7 3.8 0.00 0.389 0.389 3.60E-02

lab project 2 report

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