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1. Savonius-Darrieus Hybrid Vertical Axis Wind Turbine
with Different Number of Blades
Lydia Nurkumalawati*)
Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State
University
Pemuda No. 10 Rawamangun street, East Jakarta 13220
*) Email: 91.lydianur@gmail.com
Abstract
A Savonius-Darrieus hybrid type wind turbine design method has been developed with
different numbers of blades. Savonius wind turbines are designed in single step type, while
darrieus is used in H-Rotor type. Turbine designs are made of 2 types with different
numbers of blades between Savonius and Darrieus turbines. The first design is the number
of Savonius turbine blades (3 blades) more than the number of darrieus blades (2 blades).
In contrast, in the second design the number of darrieus turbine blades (3 blades) is greater
than the number of savonius turbine blades (2 blades). The two designs were tested with
different wind speeds then RPM (Rotation Per Minute) data, voltage and current strength
at each wind speed. Then the output power is calculated. And the resulting RPM and output
power in the second design is greater than the first design at each wind speed.
1. Introduction
Indonesia is a region that has the
potential for renewable technology power
plants, from EBTKE statistical data in 2012
through random samples from 51 regions in
Indonesia, 36 regions were proven to be
included in the classification of medium-
scale wind power potential with an average
level of wind speed at 24 meters elevation
above sea level[1]. The development of this
renewable power generation technology is
carried out due to the reduction in fossil
energy power plants. This wind potential can
be utilized by Indonesia as a cheap and
environmentally friendly renewable energy
source. By using wind turbines, wind energy
is converted into a source of electricity.
While wind turbines that are suitable for use
are vertical axis wind turbines because
vertical axis wind turbines can be driven by
even low-speed winds. During its
development, the latest vertical wind turbine
is a hybrid type. The hybrid type in a vertical
axis wind turbine is a combination of
savonius rotor and darrieus rotor in one of
vertical axis. The advantage of this type of
turbine is that it has 2 forces in its rotation,
namely the drag force (on savonius) and the
lift force (darrieus). Where the drag is
functioning in self starting turbine, while the
lift force on the airfoil serves to accelerate
the turbine rotation.
In Nature's journal, hybrid vertical wind
turbines are examined which consist of a
double stage savonius and 4 H-rotor
blades. At the same time, Rassoulinejad's
journal is conducted an experimental test
with the effect of blade arrangement on
hybrid type hybrid angina turbines. Based
on these reference journals, the research
was developed by selecting variations in
the number of blades in each rotor
(savonius & darrieus) in a hybrid type wind
turbine axis. It aims to determine the effect
of variations in the number of blades on
each rotor blade in the hybrid type vertical
angina turbine on the RPM (Rotation Per
Minute) of the turbine.
Hybrid wind turbines can be find in
the journal Nature (2010) entitled “A
Low Cut-In Speed Marine Current
Turbine”[2], a development carried out by

2. Nature and Iqbal on the design of hybrid
turbines with 4 rotor darrieus and 2
savonius double rotor blades, angular 90°
in each one. The use of sovanius dual
rotors is intended to obtain initial motion
so that the turbine runs well. The turbine
test uses water as a driving fluid, and the
maximum output power is around 21
watts when the water velocity is 0.8 m/s
and the turbine speed is around 4 rad/s.
Whereas the efficiency is around 15%
when the TSR is 2.6.
in the future, Rassoulinejad - Mousavi
conduct a research development on the
effect of blades arrangement on savonius
type vertical wind turbines such as using
single step and darrieus in the form of H-
rotors. The study was conducted with
variations in the position of savonius and
darrieus. Where high output power is
obtained in the H-rotor arrangement in
the middle of Savonius[3].
Mahendra et al (2013), in their study
entitled "Effect of Number of Blades on
the Performance of Savonius Wind
Turbine Type L", by comparing the
performance of 3 type L Savonius
turbines, each of which amounted to 2, 3,
and 4 blades. And the results on savonius
wind turbines which have the highest
performance with a total of 3 blades. In
the journal, explained the relevant
research belonging to Hendra A, whose
topic is the same as Mahendra's but has
different types of savonius turbines,
Hendra A's Savonius turbines are of type
U[4] . The results of the study are the
same, Savonius with 3 blades has a
greater performance than Savonius with
2 and 4 blades.
2. Experimental setup
the development of hybrid type
vertical axis wind turbine research has
been developed previously used to a
method (fig. 2.1). By designing turbines
with various variations in the number of
blades in each rotor. Turbine testing is
done several times in the laboratory, and
the wind source comes from the wind
tunnel.
Fig. 2.1 Hybrid type vertical turbine
Hybrid type wind turbine designs are
made in 3 types with different number of
blades between Savonius rotor and H-
rotor or H-darrieus, Savonius rotor uses
U type and one step while Darrieus rotor
uses H-Rotor or H-Darrieus type. Design
one (figure 2.1) has the same number of
blades in a wind turbine between
Savonius rotors (2 blades) and H-rotor (2
blades). In the second design (figure 2.3)
the number of H-rotor blades (3 blades)
is made more than the number of
savonius rotor blades (2) the number of
blades while in third design the H-rotor
blades (2 blades) are made less than the
number Savonius rotors (3 blades).
Fig 2.2 Design 1, hybrid type wind
turbine h-rotor (2 blades) and savonius
rotor (2 blades)
Fig 2.3 Design 2, hybrid type wind
turbine h-rotor (3 blades) and savonius
rotor (2 blades)

3. Fig 2.4 Design 2, hybrid type wind
turbine h-rotor (2 blades) and
savonius rotor (3 blades)
For making turbines, materials
from iron and for savenius rotors from
thinner used cans while for H-rotor
turbines made from balsa wood in the
form of an NACA 0021 type airfoil
where the chord length is 11 cm, the
airfoil dimeter is 2.31 cm and the height
is 45 cm. Whereas 2 blade Savonius
rotors have dimensions of 35 cm in
diameter, 19 cm in height, and blade gap
of 3 cm. For savonius 3 blades the
dimensions are 35 cm, the gap gap is 3
cm, and the position of each blade with
the other blades is 120 ° to each other.
The study was conducted at the Physics
Mechanics Laboratory, FMIPA UNJ.
Wind speed is taken by placing a
digital anemometer in front of the
blower with a distance of 0.6 meters.
Data for wind speed is taken with
variations of 0.5 m / s, 1 m / s, 1.5 m / s,
2 m / s, 2.5 m / s, 3 m / s, 3.5 m / s, 4 m
/ s, 4.5 m / s s, 5 m / s, 5.5 m / s, 6 m / s,
6.5 m / s, 7 m / s, 7.5 m / s, and 8 m / s.
Then each design was tested using
a blower with variations in wind speed
of 0.5 m / s, 1 m / s, 1.5 m / s, 2 m / s,
2.5 m / s, 3 m / s, 3.5 m / s, 4 m / s , 4.5
m / s, 5 m / s, 5.5 m / s, 6 m / s, 6.5 m /
s, 7 m / s, 7.5 m / s, and 8 m / s. The data
taken in the test are the RPM and the
output power of each design, where the
RPM is taken using a tachometer, the
output power is calculated from the
voltage and the strong current generated
by the DC motor. Where the pulley
system that connects the turbine rotation
with a DC motor.
3. Results.
After testing, RPM data and output
power at each wind speed in each turbine
design are obtained. Where the data shows
that there is an effect of the number of
different blades on the RPM and output
power.
In each turbine design an analysis is
made of the relationship between input
power and wind speed (figure 3.1), cut-in
speed analysis, RPM characteristics,
output power along with the performance,
torque, Cp, and TSR of the turbine
supported by turbine aeordinamiika
especially the lift force and the drag force .
The turbine rotor is calculated Cp each
with the formula: λ =
𝜔𝑅
𝑉 𝑤
With: ω = turbine angular velocity (rad/s)
R = turbine radius (m)
Vw= wind speed (m/s)
Figure 3.1 Graphic relationship of wind
speed to input Power in each design
Then the results of the experiments are
compared to get the turbine design with
the highest efficiency and output power,
and then reinforced with graphs. The
following graphs the results of testing
wind speed with RPM and wind speed
with the output power of each design:
Fig. 3.2 Graphs the relationship of
wind speed to RPM in each design

4. Figure 3.3 Graphic Relationship of
Wind Speed to Voltage generated in
each turbine design (variation in number
of blades)
Figure 3.4 Graphic Relationship
between Wind Speed and Output Power
in the Three Designs
In the first design, the position of the
vertical transverse darrieus just to the left
and right of the turbine (the location of
the airfoil with each other 180⁰), which
locks the turbine rotation and wind speed
can not penetrate the lock. However, at a
speed of 3.5 m/s the turbine can rotate
which can overcome the airfoil blade
locking.
The second design has 3 pieces of
darrieus blades, does not lock the turbine
rotation. This is because the number of
darrieus blades is more and the position
of the airfoil with the other airfoil is 120⁰.
The third design has 3 Savonius rotor
blades and 2 darrieus rotor blades, the
turbine rotation has a drag due to fewer
airfoil positions.
From the experimental results, design
2 which has the greatest output power is a
design that has more darrieus blades (3
blades) than the number of savonius
blades (2 blades) at each wind speed.
Optimal output power is produced by
design 2 at an 8 m / s wind speed of 1,436
x 10-2 watts. So that it can work more
optimally because the airfoil can rotate at
lower wind speeds (low wind speed). The
airfoil blade in the third design has
advantages in terms of lift force, where
the function of the lift force is to give the
turbine force to spin faster. Even the lift
force of the airfoil allows the turbine
speed to exceed the speed of the given
wind source.
Whereas in design 3, savonius blades
are more numerous than darrieus blades.
In accordance with its function, Savonius
blade moves by utilizing the drag force.
Inhibition plays a role in conducting the
initial rotation (self-starting) on the
turbine, but has limitations in turning the
turbine. Where can not also make the
turbine speed exceeds the speed of the
wind source.
From the graph we can also see the
relationship of wind speed with turbine
RPM, where the greater the speed of the
wind source given to the turbine, the
greater the turbine RPM.
Whereas in Figure 3.4, design 2
output power is always greater than
designs 1 and 3. Where the results
obtained are influenced by lift and drag.
It is also caused by the RPM and turbine
output power directly proportional to
each other. If the RPM is getting bigger,
then the output power it produces will
also be greater.
From the three graphs above, we can
see the relationship of wind speed with
RPM and output power. The relationship
is directly proportional, where the greater
the wind source, the greater the RPM and
turbine output power.
4. Conclusions
Research on the design of vertical
savonius-darrieus hybrid axis wind
turbines with variations in the number of
blades. Where design 1 number of
Savonius rotor blades (2 blades) equals
Darrieus rotor blades (2 blades), Design 2

5. Savonius rotor blades (3 blades) more
than the number of darrieus rotor blades
(2 blades), Design 3 Savonius rotor
blades (2 blades) less than the darrieus
rotor blades (3 blades). in the second
design, the number of darrieus blades is
more than the number of savonius blades,
which has a higher RPM and output
power than the first and third designs with
equal Savonius blades and more than
darrieus blades. The difference in the
number of blades in the turbine in this
study affects the output power of the
turbine, where the darrieus blade has
more influence on the lift force received
by the turbine, making the turbine rotate
more optimally.
In making turbines, the dimensions of
the turbine tower, the distance of the shaft
to the pulley, can reduce the possibility of
energy loss due to mechanical
transmission losses to the rotor generator.
5. Acknowledgments
On this occasion the authors would
like to thank all of the colleagues in the
Renewable Energy Laboratory and the
Laboratory of Physics at the Jakarta State
University Physics who helped in the
manufacture of equipment and during the
research.
Reference List
[1] Ministry of Energy and Mineral
Resources (2012). 2012 EBTKE
Statistics.
Jakarta: Ministry of Energy and Mineral
Resources.
[2] Nature, Jahangir. (2010). A low Cut-In
Speed Marine Current Turbine. Journal
of Ocean Technology, Vol 5, No.4.
[3] Rassoulinejad-Mousavi, M.S. Jamil, M.
and Layeghi, M. (2013). Experimental
Study of a Combined Three Bucket H-
Rotor with Savonius Wind Turbine.
World Applied Sciences Journal 28 (2):
205-211.
[4] Mahendra, Bayu. (2013). Effect of
Number of Blades on Performance
Savonius Turbine Type L. Journal of
FT-UB Mechanical Engineering
Students, Volume II,
No. 78.24.VII. 360.