Teknomekanik
Vol.5, No.1, June 2022, pp. 13~27
e-ISSN: 2621-8720 p-ISSN: 2621-9980

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13

The Wind Turbine Design and Test
Mark Irwin Paranchis1 and Hendri Pratama2*
1Kolej Vokasional Sandakan, Sadakan 90713, Malaysia
2Sultan Idris Education University, Tanjong Malim 35900, Malaysia

Article Info

ABSTRACT

Article history:

Green energy harvester, known as wind turbine, able to convert mechanical works to
electrical power. There are two main type of wind turbine that considered thoroughly,
which are the horizontal and vertical axis wind turbine respectively. This project mainly
focuses on the design of new wind turbine that can operate well together in low wind
speed condition in Malaysia. For the first stage of this project, the problems, purpose,
and planning regarding the project were properly determined. Literature survey then
further analyzed in order to know the wind power or behavior across the world, and
specifically in Malaysia, research on turbine that can work in low wind speed condition,
as well as parameter that are often used in designing wind turbine by previous
researcher. From the literature survey, the selected turbine was a Three-Bladed
Savonius Wind Turbine, which is one type of Vertical Axis Wind Turbine (VAWT). That
turbine will be attached to another VAWT turbine system to help generate more power
and better performance. Design theoretical calculation and material selection have
been properly analyzed before fabrication can be done. Upon completion of the
fabrication, Savonius wind turbine section properly tested through experimental works
by using simple wind tunnel in Faculty of Engineering Mechanical Workshop, and all
readings and data collected using applicable tools and equipment. For the experimental
works of Savonius rotor, the variable includes of blades curve angle from its center at
different wind speeds. The data collected then interpreted through charts and graph for
comparison and performance analysis, and conclude that 1200 blades curve angle from
its center was the best among the other type of blades. From this project, it can be
concluded that this type of mix wind turbine able to works in low wind speed condition
in Malaysia, but a better improvisation and modification of the mix wind turbine will
certainly improve its further performance and efficiency.

Received Feb 12th, 2022
Revised Apr 26th, 2022
Accepted May 16th, 2022

Keywords:
Wind
Turbine
Savonius
Darrieus
VAWT

Corresponding Author:
Hendri Pratama,
Sultan Idris Education University,
Perak 35900, Malaysia
Email: hendripratama.tvet@gmail.com

1.

INTRODUCTION

Energy is essential in human life all over the world, in which it comes from many forms of energy
including solar, wind, and hydro (water). With energy, many types of works can be done. Energy can help us
to wash and dry our clothes, cook our foods, light up cities, as well as power up machinery in factories and
devices. These energy demands increase rapidly every years in order to do severe tasks and generate powers,
and it can be either harmful or safe. This proposal was done to pin point out the extraction of green and safer
wind energy in which wind turbine was selected. Based on the previous wind turbines, especially vertical axis
wind turbines, new wind turbines design and test proposed that can operate under low wind speed in Malaysia.
Thus, low wind speed operated wind turbines must be further studied and analyzed in order to design and test
it. Green energy comes from natural sources such as sunlight, wind, rain, tides, plants, algae and geothermal
heat. These energy resources are renewable and naturally replenished. In contrast, fossil fuels are a finite
resource that take millions of years to develop and will continue to diminish with use. In Klang Valley,
Malaysia, data of pollution produced from fossil fuels were collected and it caused concern due to estimated
environmental damage because of increasing level of dangerous chemical composition produced from fossil
fuels, although the level still below of acceptable limit by World Health Organization (WHO) [1].
The green energy, or more specifically, renewable energy becomes more important as time goes by as
this kind of energy cannot be depleted, or in other words, it can be reuse or renewable. In Iceland, Geothermal

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Vol.5, No.1, June 2022, pp. 13~27

and hydropower is the primary energy supply as almost all electricity produced in Iceland derives from
hydropower plants and from geothermal plants. The stream flow in rivers used for hydropower energy tends
to exhibit a large annual variation, with larger flow during summer than in winter, while the annual cycle of
wind in the country has the opposite phase, with stronger winds in winter than in summer. Thus, wind can be
harvested and can be use efficiently by combining it with hydropower [2].
Of course, wind can produce mechanical works and electrical power, and it certainly depends on the wind
characteristics and energy, and all this matter depends on the availability of wind on the specify place.
Insufficient wind energy or power will cause difficulty or failure for machineries or more specifically, wind
turbines to efficiently and properly work. As commonly known, high wind speed produced from huge plain
field or seashore and low wind speed produced inland. Figure 1 below shows the Global renewable resources
available around the globe, and Figure 2 shows the Global wind speed map across the globe.

Figure 1: Global Renewable Resources across the Globe [3]

Figure 2: Wind Speed Map across the Globe [3]
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Besides of all renewable energy power machine or plants, wind turbine considered and approved as one
of the green and renewable energy harvester to generate power and electricity. Since the increasing demand
for electricity and reduction of pollution and global warming, the research and improvement of wind turbine
were forced and encouraged [4]. Generally, there are two types of wind turbine commonly known, horizontal
axis and vertical axis wind turbine with advantages and disadvantages of their own [5]. Horizontal wind
turbines can produce high and commercial energy and they were built tall in order to capture fast moving
laminar air currents, due to large rotor, the laminar wind pass through it will become turbulent, other than its
big weight, high maintenance cost and it is not suitable for residential use. Unlike horizontal wind turbine,
vertical axis wind turbines built closer to ground and able to harvest lower wind speed due to its blade as well
as suitable for residential use [6].
In Malaysia, particularly in Sabah region, the wind speed can be considered low at 5 km/h to 7 km/h [7].
Based on this wind speed condition, vertical wind turbine able to deal with this situation as it able to harvest
low wind speed easily. The other benefit of this turbine includes of its lightweight and low cost maintenance.
The operational work system of vertical axis wind turbine is simple where rotary motion of the blade and shaft
produced energy and stored onto battery. This power will be use later by supplying the electrical current from
the battery itself which store the charge from the wind turbine [8]. Although vertical axis wind turbines have
the ability to capture wind from many angles, the speed of the wind caused trouble and difficulty for this turbine
to works smoothly.
Generally, there are several types of wind turbines, and two types of vertical wind turbines that commonly
known were Darrieus and Savonius Wind Turbine. Darrieus wind turbines was the first aerodynamic vertical
axis wind turbine developed by Georges Darrieus in France and first patented in 1927. The wind that passing
through the turbines blade will determine its speed, and resulting apparent wind throughout whole revolution
coming in as a head wind with only a limited variation of angle. Meanwhile, Savonius wind turbine introduced
by Finnish Engineer S.J. Savonius in 1922. The operational work for this type of turbine is simple, in which,
each cups that fixed to a central shaft in opposing directions, will capture wind and rotating the shaft, and the
energy will go through the generator [9].
As technology keep advancing, researches have been done in order to improve the aerodynamic system
of the turbine. One of the blades type that very common was the airplanes airfoil. The performance and
thickness of this airfoils are not necessarily good for wind turbine airfoils. However, it do have benefits from
extensive laminar flow and associated low drag [10]. Size of the airfoils will depends on the machine size as
the Reynold numbers must be considered to avoid significant laminar separation bubbles that will causes noise,
excessive drag, and inconsistent maximum lift. Besides that, helical type blade design also another type of
blades for wind turbine, but comes with a bad design which looks like a screw. The twisted design of the blade
used to harvest the wind energy but unfortunately eliminating the drag caused by the rotational motion. It also
did not produce high annual energy even if the blades rotates faster [11]. Based on this situation, it shows that
there were actually many types of wind turbine blades but not used by manufacturer due to its efficiency.
Other than that, the number of blades used for the wind turbines also affect its performance and efficiency.
According to the previous research done for savonius wind turbine blades, it shows that two blades savonius
wind turbine have higher torque coefficient and power coefficient rather than three blades savonius wind
turbine [12]. This analysis can be done by using FEM and CFD analysis. In this project, three-bladed savonius
rotor used instead of two-bladed savonius rotor to investigate its impact on performance and efficiency.
Moreover, the angle of the blades surely will affect the performance of the turbines especially in the
process of harvesting winds. According to the previous research done on vertical axis wind turbine,
specifically, the savonius wind turbine rotor or blade, the static and dynamic torque coefficient, velocity and
the pressure across the blades were determined according to different angle of the rotor or blades. All the
simulation were done by using simulation software. The aim of all this simulation and calculations is to show
the influence of the geometrical parameters on the flow structures in order to increase the efficiency of the
Savonius rotors [13].
Vertical axis wind turbine is the most suitable type of wind turbine that can be used in Malaysia, especially
in Sabah, because it can deal with low wind speed. A mix turbine must be built with combination of different
type of blades so that it will be able to make a self-start and work more effectively. The performance of the
mix turbine system will further studied and analysed based on the blades specification or profile, in order to
deal with the low wind speed condition. Therefore, this study aims to focus on the design of new wind turbines
that can work well in low wind conditions in Malaysia. The turbine in this study was designed to operate at
low wind speeds and parameters that were often used by previous researchers in the form of wind turbines.
These turbines will later be installed in other VAWT turbine systems to help generate more power and better
performance.

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2.

MATERIAL AND METHODS

Vol.5, No.1, June 2022, pp. 13~27

In design process, theories and calculations correlated in finding best dimension for the Savonius wind
turbine prototype. For this project, there are four stages in the designing process. The first stage is the wind
turbine design parameter. The second stage is the Savonius wind turbine drawing and 3D views. The third
stage is dimensional analysis of the design and the last stage will be the fabrication of the prototype with
specified dimensions and materials [14]. The experiment for Savonius wind turbine done after the fabrication
of the wind turbine complete and these data from experiment used to determine the performance of the mix
wind turbine.
As this experiment focused more to the Savonius wind turbine section from the mix wind turbine. As for
Savonius wind turbine that commonly seen that using two blades to operates, this experiment focus on three
Savonius blades to operate. The variables that would be used to determine the performance of the wind turbine
was the dimension of the blades, which was the degree of curve of the blades that will differentiate the swept
area. The degree of curve of the blades used includes 30o, 60o, 90o, and 120o.
Furthermore, the wind speed will be varied to determine the power that the turbine can produced at
specified wind speed. From these variables, the rotation speed of the turbine, torque, and power generated by
the turbine can be determine. The main purpose of this experiment is to determine the performance of the mix
wind turbine, and focused more to Savonius wind turbine section. The experiment conducted in Engineering
Faculty Mechanical Workshop by using simple wind tunnel system.
2.1 Test procedure
The first variable that most important in this experiment was the wind speed. The wind speed from the
wind tunnel was adjusted based on the distance of the turbine with the wind tunnel. The wind speed from wind
tunnel adjusted using anemometer and the ground marked or pointed after required wind speed achieved. The
wind speed that used in the experiment were 1 m/s, 2 m/s, and 3 m/s. The second variable examined was the
angle of curve from center of the blades for the Savonius wind turbine. The blades’ angle of the curve from its
center used in this experiment were 30o, 60o, 90o, and 120o. This blade can be changed from the turbine with
the bolt and nuts feature. For the entire experiment, the Savonius wind turbine section were tested for several
value of wind speed according to the blades curve degree angle.
2.2 Data collection and equipment
For the experimental work, tools and equipment for measuring, calibration and data collection must be
determined for a smoother operation during experimental work. Data was collected through observation and
documentation of images and videos as reporting and evaluation material. The turbine is placed on different
distances from the simple wind tunnel and the distances between them determined from measured wind speed
using anemometer. Besides that, the amount of rotation per minutes produce from the rotating Savonius wind
turbine section can be determined by using bicycle rotation sensor. Mobile video camera would be used if
there is difficulty to take readings from the sensor. The RPM would be counted properly based on the slowmotion turbine rotation from the video. The power generated from the wind turbine motor can be calculated
using wind turbine controller. Digital multimeter used in case the controller malfunction. Wiring circuit used
as alternative in case the power generated from the motor not sufficient for the controller to work [25]. The
wiring circuit included with rectifier, capacitor, wires, wiring hub, and light bulb with 5 W of power.
2.3 Design parameters
2.3.1 Wind power
Since selecting a suitable wind turbine for specific location is important, thus, the wind power must be
also important to be considered. The wind power, Pw can be defined as the multiplication of mass flow rate,
pAV and the kinetic energy per unit mass, ½V2 [15], and can be denoted as,
1

𝑃𝑤 = 2 𝜌𝐴𝑉 3

(1)

Where, 𝑃𝑤 is wind power, 𝜌 is density of air, 𝐴 is swept area and V is velocity.
Equation 2.5 is an equation of ideal power of wind turbine in case of no aerodynamics and any other loses
in energy conversion. Unfortunately, it is impossible that all energy can be converted into useful energy as

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stated by Betz Limit [16]. The maximum power coefficient, Cp for Savonius rotor is 0.30, and thus the power
output, P by considering the power efficiency can be denoted as,
𝑃𝑤 = 0.15 𝜌𝐴𝑉 3

(2)

2.3.2 Swept Area
Swept area is a method to know and calculate the amount of wind energy intercepted by turbines,
specifically Savonius wind turbine which then can have a better comparison between turbines in similar wind
regimes. Simply say, swept area is the section area in which turbines hit by wind to generate rotating force. It
is found that swept area for Savonius wind turbine calculated by multiplication of rotor diameter, D and rotor
height, H [17]. The equation donated as,
𝐴 = 𝐷𝐻

(3)

Where, A is swept area, D is rotor diameter and H is rotor height.
2.3.3 Wind Speed
Power output affected by wind speed as it is the major element for it. There are three main parameters
which includes cut-in speed, rated wind speed, and cut-out speed [18], and can be denoted as follow:
𝑉𝑐𝑢𝑡−𝑖𝑛 = 0.5 𝑉𝑎𝑣𝑔

(4)

𝑉𝑟𝑎𝑡𝑒𝑑 = 1.5 𝑉𝑎𝑣𝑔

(5)

𝑉𝑐𝑢𝑡−𝑜𝑢𝑡 = 3.0 𝑉𝑎𝑣𝑔

(6)

2.3.4 Aspect Ratio
Aerodynamic performance of Savonius rotor can be evaluated by considering the aspect ratio [19] and
[20], in which the rotor height is twice of the rotor diameter for better stability and efficiency. The equation
can be denoted as,
𝐴𝑅 = 𝐻/𝐷

(7)

2.3.5 Tip Speed Ratio
Another important thing has to be considered is tip speed ratio. Tip speed ratio, 𝜆 can be described as the
ratio of rotor blade, 𝜔. 𝑅 to the undisturbed wind speed, V [21]. The maximum tip speed ratio can be achieve
is 1 and the performance of wind turbine improves when tip speed ratio increase, by increasing the rotational
rate of rotor [16]. The equation denoted as:
𝜆 = 𝜔. 𝑅/𝑉
(8)
Where, 𝜆 is tip speed ratio, 𝜔 is angular velocity, 𝑅 is the radius revolving part of the turbine, and V is
the undisturbed wind speed.
2.3.6 Solidity
Solidity best described as the ratio of blade area to the turbine rotor swept area. Solidity can be related
and inversely proportional with tip speed ratio, in which, a higher tip speed ratio will result in low solidity. For
vertical axis wind turbine, the equation denoted as,
𝜎 = 𝑛𝑑/𝑅

(9)

Where, n is the number of blades, d is chord length or diameter of each half cylinder, R is the radius of
wind turbine. According to many research, number of blades is directly proportional to performance of turbine.
However, some researchers found that two-blade Savonius rotor resulting in better turbines performance than
three-blade Savonius rotor [22] and [23].

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2.3.7 Moment of Inertia
The other important parameter in designing savonius wind turbine is moment of inertia. This parameter
will tells us the amount of energy stored or required to rotate rotor to a particular velocity [12]. The equation
can be denoted as,
𝐼 = 𝐼𝑏 + 2𝐼𝑝 + 𝐼𝑠 + 𝐼𝑑

(10)

Where, 𝐼𝑏 is the blades moment of inertia, 𝐼𝑝 is the end plates moment of inertia, 𝐼𝑠 is shaft moment of inertia,
and 𝐼𝑑 is torque measuring disc moment of inertia.
The moment of inertia for two bladed and three bladed Savonius wind turbines respectively given as:
8

𝐼2𝑏 = 3𝜋 𝑚. 𝑑 2
4

𝐼3𝑏 = 𝜋 𝑚. 𝑑 2

(11)
(12)

2.3.8 Torque
Torque can be defined as the force acting tangentially over the rotor blade operating at a distance of rotor
radius, d from the Centre [12], and denoted as,
𝜏 = 𝐼𝛼

(13)

But, in this project the torque formula that would be used for easier and better calculation and result given as:
𝜏=

𝑃

(14)

𝜔

Based on the theories and calculations decided and made for the design, the main dimensions and threedimensional views via SolidWorks software for the design have been made. The shaft fabricated using PVC
pipe, the riveted hinges made of light stainless steels, and all type of blades used made of thin aluminum sheets.

Figure 3: Three-Dimensional View of Savonius Wind Turbine
As what can be seen in Figure 3, it was a three-dimensional view of the Savonius wind turbine. The
purposed of this project is to build a mix wind turbine with combination of Savonius wind turbine operating
system and darrieus wind turbine operating system. In this project, only Savonius wind turbine which placed
on top of the darrieus wind turbine for the mix wind turbine will be further study and focused. Moreover, the
assembly of the top part of the mix wind turbine, which was the Savonius wind turbine can be looked closer
and specifically via exploded view that can have been done by using Solid works Software. Figure 4 shows the
exploded view of the Savonius wind turbine.
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Vol.5, No.1, June 2022, pp. 13~27

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Figure 4: Exploded View of Savonius Wind Turbine

Figure 5: Two-Dimensional Drawing of Savonius Wind Turbine
In addition, the two-dimensional drawing with the main dimensions also shown in Figure 5. This allow
reader or fabrication engineers to understand more regarding for this design, and the drawing was made by
using Solid works Software which is beneficial to its user.
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Vol.5, No.1, June 2022, pp. 13~27

Figure 6: Three-Dimensional Drawing of Mix Wind Turbine
Meanwhile, Figure 6 shows the 3D view of the whole assembly of the mix wind turbine that will be tested.
Figure 7 also shows the fabricated prototype during on experimental works.

Figure 7: Mix Wind Turbine full assembly during experimental works
3.

RESULTS AND DISCUSSION

Further study and calculation was focused on the savonius rotor section, specifically for the theoretical
tip speed ratio, torque and power that can be produced from only savonius section without any additional load.
From the calculation result obtained for the design, a three-dimensional savonius wind turbine, as well as the
whole assembly of mix wind turbine model modelled through CAD/CAM software, called SolidWorks. From
the assembly, a simple simulation was done to the savonius rotor, as well as the whole mix wind turbine
structure to determine the potential of the savonius rotor to be workable, as well as mix wind turbine as a whole.
Based on the design proposed, fabrication of mix wind turbine can be proceed. Then, The mix wind turbine,
specifically for the savonius rotor, undergo several tests with its blades curve angle from its centre and wind
speed as the variables. All readings and data was taken and noted down.
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Vol.5, No.1, June 2022, pp. 13~27

21

3.1 Design Calculation
As for design calculation, the calculation will focus on the performance availability from only the
savonius wind turbine system alone. Specific design parameters considered for the Savonius wind turbine rotor,
that will be synchronized with Darrieus wind turbine rotor. These parameters also done by refering to Betz
limit as shown in Figure 8.

Figure 8: Betz Limit Chart [24]
Meanwhile, the design calculation result summary is shown in Table 1 below.
Table 1: Design Calculation Result Summary Table
Parameter
Swept Area, A
Aspect Ratio, AR
Cut-In Wind Speed, 𝑽𝒄𝒖𝒕−𝒊𝒏
Rated Wind Speed, 𝑽𝒓𝒂𝒕𝒆𝒅
Cut-out wind speed, 𝑽𝒄𝒖𝒕−𝒐𝒖𝒕
Tip Speed Ratio, 𝝀
Solidity, 𝝈
Moment of Inertia, 𝑰
Torque, 𝝉
Power, P
Wind Power, 𝑷𝒘

Design Calculation Result
0.0657 𝑚2
1.37
1 𝑚/𝑠
3 𝑚/𝑠
6 𝑚/𝑠
2.19
1.37
8.226 × 10−3 𝑘𝑔/𝑚2
25 𝑁𝑚
1kW
0.2205 𝑊

Based on the experimental works for Savonius turbine and mix wind turbine as a whole, the
summarization of the data result as well as data analysis are shown as in the next tables, figures, and graphs
respectively.
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Vol.5, No.1, June 2022, pp. 13~27
Table 2: Savonius RPM Without Load Based on Blades Curve
wind speed, V (m/s)
1
2
3
wind speed, V (m/s)
1
2
3

Revolution Per Minute Without Load (RPM)
30
60
90
120
62
73
91
103
81
89
112
115
114
130
153
217
Revolution Per Minute with Load (RPM)
30
60
90
120
51
69
82
91
70
81
93
101
99
121
140
184

Table 3: Result Calculated for Savonius Wind Turbine system at wind speed of 1 m/s with Savonius blades at
30o,60o,90o, and 120o
Savonius, 1 m/s, 30°
No

Voltage,
V (V)

Resistance
(Ω)

1
2
3
4
Average

0.543
0.327
0.433
0.545
0.462

0.22
0.22
0.22
0.22
0.22

Resistance
Voltage,
VΩ (VΩ)
0.003
0.0013
0.0025
0.0032
0.0025

1
2
3
4
Average

0.611
0.659
0.594
0.667
0.63275

0.22
0.22
0.22
0.22
0.22

0.0054
0.0059
0.0046
0.0064
0.005575

1
2
3
4
Average

0.679
0.682
0.699
0.703
0.69075

0.22
0.22
0.22
0.22
0.22

0.0075
0.0089
0.0097
0.0099
0.009

1
2
3
4
Average

0.732
0.753
0.741
0.749
0.74375

0.22
0.22
0.22
0.22
0.22

0.014
0.035
0.022
0.03
0.02525

Current, I (A)

Power, P (W)

0.013636364
0.007404545
0.005909091
0.001932273
0.011363636
0.004920455
0.014545455
0.007927273
0.011363636
0.005546136
Savonius, 1 m/s, 60°
0.024545455
0.014997273
0.026818182
0.017673182
0.020909091
0.01242
0.029090909
0.019403636
0.025340909
0.016123523
Savonius, 1 m/s, 90°
0.034090909
0.023147727
0.040454545
0.02759
0.044090909
0.030819545
0.045
0.031635
0.040909091
0.028298068
Savonius, 1 m/s, 120°
0.063636364
0.046581818
0.159090909
0.119795455
0.1
0.0741
0.136363636
0.102136364
0.114772727
0.085653409

Torque, T
(Nm)

Tip Speed
Ratio, λ

51
40
48
51
47.5

Angular
Speed, ω
(rad/s)
5.431
4.189
5.027
5.341
4.9745

0.001386359
0.000461273
0.000978805
0.00148423
0.001077667

0.514044545
0.403170305
0.483823615
0.514044545
0.478770753

61
65
58
69
63.25

6.388
6.807
6.0734
7.226
6.6236

0.002347726
0.002596325
0.002044983
0.002685253
0.002418572

0.6234688
0.66443632
0.59276384
0.7052576
0.64646336

72
75
78
80
76.25

7.54
7.854
8.168
8.378
7.985

0.00306999
0.00351286
0.003773206
0.003775961
0.003533004

0.81432
0.848232
0.882144
0.904824
0.86238

83
90
85
88
86.5

8.692
9.425
8.901
9.215
9.05825

0.00535916
0.012710393
0.008324907
0.011083707
0.009369542

1.0047952
1.08953
1.0289556
1.065254
1.0471337

Rotational
Speed (RPM)

Table 4: Result Calculated for Savonius Wind Turbine system at wind speed of 2 m/s with Savonius blades at
30o,60o,90o, and 120o
Savonius, 2 m/s, 30°
No

Voltage,
V (V)

Resistance
(Ω)

1
2
3
4
Average

0.778
0.799
0.785
0.79
0.788

0.22
0.22
0.22
0.22
0.22

Resistance
Voltage,
VΩ (VΩ)
0.046
0.067
0.054
0.061
0.057

1
2
3
4
Average

0.831
0.798
0.855
0.86
0.836

0.22
0.22
0.22
0.22
0.22

0.075
0.067
0.083
0.084
0.07725

1
2
3
4
Average

0.903
1.201
1.11
0.922
1.034

0.22
0.22
0.22
0.22
0.22

0.095
0.119
0.103
0.098
0.10375

1

1.45

0.22

0.139

Current, I (A)

Power, P (W)

0.209090909
0.162672727
0.304545455
0.243331818
0.245454545
0.192681818
0.277272727
0.219045455
0.259090909
0.204432955
Savonius, 2 m/s, 60°
0.340909091
0.283295455
0.033155153
0.243027273
0.040005976
0.322568182
0.040201229
0.328363636
0.037480332
0.294313636
Savonius, 2 m/s, 90°
0.045971683
0.389931818
0.069702985
0.649631818
0.058384655
0.519681818
0.047251391
0.410709091
0.055327679
0.492488636
Savonius, 2 m/s, 120°
0.094068833
0.916136364

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Torque, T
(Nm)

Tip Speed
Ratio, λ

61
68
65
67
65.25

Angular
Speed, ω
(rad/s)
6.388
7.121
6.807
7.016
6.833

0.025465361
0.034171018
0.028306423
0.031220846
0.029790912

0.30740653
0.342680323
0.327569858
0.33762746
0.328821043

74
70
77
78
74.75

7.749
7.33
8.063
8.168
7.8275

0.036558969
0.033155153
0.040005976
0.040201229
0.037480332

0.3781512
0.357704
0.3985984
0.3985984
0.381982

81
89
85
83
84.5

8.482
9.32
8.901
8.692
8.84875

0.045971683
0.069702985
0.058384655
0.047251391
0.055327679

0.458028
0.50328
0.480654
0.469368
0.4778325

93

9.739

0.094068833

0.5629142

Rotational
Speed (RPM)

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Vol.5, No.1, June 2022, pp. 13~27
2
3
4
Average

1.322
1.509
1.498
1.44475

0.22
0.22
0.22
0.22

0.122
0.146
0.142
0.13725

0.077783458
0.058384655
0.047251391
0.055327679

0.733109091
1.001427273
0.966890909
0.904390909

90
96
95
93.5

9.425
10.053
9.948
9.79125

0.077783458
0.099614769
0.097194502
0.092165391

23

0.544765
0.5810634
0.5749944
0.56593425

Table 5: Result Calculated for Savonius Wind Turbine system at wind speed of 3 m/s with Savonius blades at
30o,60o,90o, and 120o
Savonius, 3 m/s, 30°
No

Voltage,
V (V)

Resistance
(Ω)

1
2
3
4
Average

0.993
0.798
1.132
0.809
0.933

0.22
0.22
0.22
0.22
0.22

Resistance
Voltage,
VΩ (VΩ)
0.097
0.083
0.128
0.089
0.09925

1
2
3
4
Average

1.534
2.01
2.772
2.544
2.215

0.22
0.22
0.22
0.22
0.22

0.151
0.198
0.279
0.253
0.22025

1
2
3
4
Average

2.974
3.331
4.055
3.65
3.5025

0.22
0.22
0.22
0.22
0.22

0.298
0.349
0.403
0.373
0.35575

1
2
3
4
Average

4.531
4.377
4.83
4.652
4.5975

0.22
0.22
0.22
0.22
0.22

0.457
0.381
0.612
0.588
0.5095

Current, I (A)

Power, P (W)

Torque, T
(Nm)

Tip Speed
Ratio, λ

90
89
93
91
90.75

Angular
Speed, ω
(rad/s)
9.425
9.32
9.739
9.529
9.50325

0.04645334
0.032302965
0.06762688
0.034345395
0.045182145

0.302369708
0.299001133
0.312443352
0.305706202
0.304880099

102
114
120
116
113

10.681
11.938
12.566
12.147
11.833

0.09857521
0.15153292
0.279754894
0.240849592
0.192678154

0.347488533
0.388382933
0.408813867
0.3951824
0.384966933

124
131
146
137
134.5

12.985
13.718
15.289
14.347
14.08475

0.310236287
0.385200268
0.485840979
0.431338196
0.403153932

0.46746
0.493848
0.550404
0.516492
0.507051

163
153
198
170
171

17.069
16.022
20.735
17.802
17.907

0.551416177
0.473109985
0.647995265
0.698434292
0.59273893

0.657725467
0.617381067
0.798988667
0.6859704
0.6900164

Rotational
Speed (RPM)

0.440909091
0.437822727
0.377272727
0.301063636
0.581818182
0.658618182
0.404545455
0.327277273
0.451136364
0.431195455
Savonius, 3 m/s, 60°
0.686363636
1.052881818
0.9
1.809
1.268181818
3.5154
1.15
2.9256
1.001136364
2.325720455
Savonius, 3 m/s, 90°
1.354545455
4.028418182
1.586363636
5.284177273
1.831818182
7.428022727
1.695454545
6.188409091
1.617045455
5.732256818
Savonius, 3 m/s, 120°
2.077272727
9.412122727
1.731818182
7.580168182
2.781818182
13.43618182
2.672727273
12.43352727
2.315909091
10.7155

250
217
200

153
150

130
112

103
91

100

81

73

115

114

89

62
50

0
1 m/s

2 m/s
30 Deg.

60 Deg.

90 Deg.

3 m/s
120 Deg.

Figure 9: Savonius RPM Without Load Based on Blades Curve

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Vol.5, No.1, June 2022, pp. 13~27
200

24

184

180
160
140
140
121
120
100

82

80
60

93

91

101

99

81
70

69

51

40
20
0
1 m/s

2 m/s
30 Deg.

60 Deg.

90 Deg.

3 m/s
120 Deg.

Figure 10: Savonius RPM With Load Based On Blades Curve
Based on the bar chart in Figure 9 and 10 for Savonius RPM without load and with load respectively, it
shows that by overall all types of blades able to produce higher RPM if there is any load including motor
attached to it. From those two figures, it shows that 120o of blades curve angle from its center produce the
highest among the other blades while 30o blades curve angle from its center shows lowest RPM generated. By
mechanical theory and concept, higher RPM means higher torque and power able to be produced, and thus
120o curve of blades would be able to produce highest power among the other blades. The reason on why the
RPM of all the blades decreased when having load attached on it was because of the weight of the other part
of the turbine that the blades and whole assembly of the Savonius wind turbine have to counter. The coupling
mechanism also influenced the smoothness of the system. Besides that, the wind distribution also biased to the
surrounding as the test did not run inside a total enclosed area.
0,7
0,6
0,5

30 Degree

Torque, T (𝜏)

0,4

60 Degree
0,3

90 Degree

0,2

120 Degree

0,1
0
0

0,5

1

1,5

2

Wind Speed, V (m/s)

2,5

3

3,5

Figure 11: Graph of Torque, 𝜏 Against Wind Speed, V Produce for Savonius Rotor

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25

1,2

Tip Speed Ratio, 𝜆

1
0,8

30 Degree

0,6

60 Degree
90 Degree

0,4

120 Degree
0,2
0
0

0,5

1

1,5

2

2,5

3

3,5

Wind Speed, V (m/s)

Figure 12: Graph of Tip Speed Ratio, 𝜆 Against Wind Speed, V for Savonius Rotor
12
10

Power, P (W)

8
30 Degree

6

60 Degree
4

90 Degree
120 Degree

2
0
0

0,5

-2

1

1,5

2

2,5

3

3,5

Wind Speed, V (m/s)

Figure 13: Graph of Power, P Against Wind Speed, V for Savonius Rotor
By referring to Fig. 11, Fig. 12, and Fig. 13, it clearly shows that the torque, tip speed ratio, and power
generated at its best when mix wind turbine - Savonius turbine blades at 120o and at its worst performance at
blades curve degree angle of 30o.
4.

CONCLUSION

The mix wind turbine project main objectives were to analyze the outcome based on three-bladed savonius
blade design, and to study the torque and power produced by the turbine based on the savonius blade profile
or specification. The data and analysis show that this kind of turbine, mix wind turbine is workable as it able
to rotate even in low wind speed from 1 m/s to 3 m/s. Furthermore, it able to generate power from kinetic
mechanical energy as a result from rotation. All this objective intended to determine the best dimension or type
of savonius blade for the three-bladed savonius section of the mix wind turbine. Based on the data analysis of
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Vol.5, No.1, June 2022, pp. 13~27

the experimental works, it shows that 120o blades curve angle from its centre shows highest RPM in increasing
wind speed compared to the other blades either in without load or with load condition, and 30o blades curve
angle shows the lowest RPM among the other type of blades. Furthermore, 120o blades curve angle of Savonius
wind turbine from its centre shows the best production of power, torque and tip speed ratio among the other
types of blade starting from 1 m/s to 3 m/s. Meanwhile, 30o of blades shows the worst performance among the
other types of blade. There are difference between the value obtained from design theoretical calculation results
and experimental results and it might cause by some errors in material and design, or test tools and equipment.
Based on the experimental data analysis, by overall, it shows that three-bladed wind turbine able to works as
well as two-bladed savonius rotor as the performance was quite good, and tip speed ratio can be reached slightly
more than ideal tip speed ratio with value of 1. 120o blades curve angle from its centre is the best and most
suitable type of blade that can be used for savonius wind turbine and mix wind turbine itself for better
performance and efficiency.Future works should focus more on the design of the mix wind turbine, or more
specifically to the synchronization mechanism between two types of wind turbine system. A more thorough
design calculation should be endorsed and a better selection of material for fabrication should be upgraded for
a better result outcome, but still have to considered for all required and relative cost.
ACKNOWLEDGEMENT
We would like to express our sincere gratitude to the faculty of mechanical and manufacturing, and also
to innovation committee, of Sandakan Vocational College for their financial and facility supports provided
upon completion of this research project.
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