VAWT Project

DESIGN AND FABRICATION OF VERTICAL AXIS
WIND TURBINE
A project report submitted at
Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal
in partial fulfillment of the degree
Bachelor of Engineering
in
Mechanical Engineering
Submitted by
Harshit Singh (0827ME101021)
Punit Purohit (0827ME101038)
Rohit Nayek (0827ME101044)
Saket Sharma (0827ME101047)
Shreyans Gangwal (0827ME101054)
Mechanical Engineering Department
Acropolis Institute of Technology and Research, Indore
2013-2014

CERTIFICATE
This is to certify that Harshit Singh (0827ME101021), Punit Purohit (0827ME101038), Rohit
Nayek (0827ME101044), Saket Sharma (0827ME101047), Shreyans Gangwal (0827ME101054)
have completed their project work, titled “DESIGN AND FABRICATION OF VERTICAL
AXIS WIND TURBINE” as per the syllabus and have submitted a satisfactory report as a
partial fulfillment towards the degree of Bachelor of Engineering in Mechanical Engineering
from Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal.
Prof. Himanshu Bhiwapurkar
Project Guide
Prof. Prashant Geete
Project Coordinator
Prof. Tapan Jain
Head of Department
______________ _ _______________
Internal Examiner External Examiner
I

ACKNOWLEDGEMENT
I am thankful to our technical university RGPV, Bhopal that they have given me chance to
convert my theoretical knowledge into the practical skills through this project.
Any work of this magnitude requires input, efforts and encouragement of people from all sides
in compiling this project. I have been fortunate enough to get active and kind co-operation from
many people without my endeavors wouldn’t have been a success.
The project work has been made successful by the cumbersome effort of the faculties.
I would like to express my deep gratitude to my project guide Prof. Himanshu
under whose valuable guidance I was able to complete my project smoothly.
I am thankful to our Head of Mechanical Engg. Department Prof. Tapan Jain for encouraging me
regularly and providing me each and every facility.
Lastly, I am thankful to each and every person involved directly or indirectly in the project work.
Harshit Singh (0827ME101020)
Punit Purohit (0827ME101034)
Rohit Nayek (0827ME101044)
Saket Sharma (0827ME101047)
Shreyans Gangwal (0827ME101020)
II

ABSTRACT
We know that there is enough wind globally to satisfy much, or even most, of humanity's energy
requirements – if it could be harvested effectively and on a large scale. If the efficiency of a wind
turbine is increased, then more power can be generated thus decreasing the need for expensive
power generators that cause pollution. Vertical axis wind turbines (VAWTs), which may be as
efficient as current horizontal axis systems, might be practical, simpler and significantly cheaper
to build maintain than horizontal axis wind turbines (HAWTs).
Savonius wind turbine also have other inherent advantages, such as they are always facing the
wind, which might make them a significant player in our quest for cheaper, cleaner renewable
sources of electricity.
VAWTs might even critical in mitigating grid interconnect stability and reliability issue currently
facing electricity producers and suppliers. Additionally, cheap VAWT’s may provide an
alternative to the rain forest destruction for the growing of bio-fuel crops.
Vertical-axis wind turbines (VAWTs) are a type of wind turbine where the main rotor shaft is set
vertically. Among the advantages of this arrangement are that generators and gearboxes can be
placed close to the ground, and that VAWTs do not need to be pointed into the wind.
Major drawbacks for the early designs (Savonius, Darrieus, and cycloturbine) included the
pulsatory torque that can be produced during each revolution and the huge bending moments on
the blades. Some geographic features such as mountains also have an influence upon wind.
Mountains can create mountain breezes at night, because of the cooler air flowing down the
mountain and being heated by the warmer valley air causing convection current.
In this project we attempt to design and fabricate a Savonius Vertical Axis Wind Turbine with
the help of various interfaces software Catia V5R16, Autodesk Simulation CFD 2014.
III

CONTENTS
CHAPTER 1
INTRODUCTION………………………………………………………………………………...1
1.1 BACKGROUND OF THE VAWT…………………………………………………………...3
1.2 SAVONIUS WIND TURBINE……………………………………………………………….4
1.3 PRINCIPLE OF OPERATION……………………………………………………………….5
1.4 CHARACTERISTICS OF VAWT……………………………………………………………6
1.5 REQUIRMENT OF PLACING……………………………………………………………….6
CHAPTER 2
LITERATURE REVIEW…………………………………………………………………………8
CHAPTER 3
PROBLEM DEFINATION……………………………………………………………………...11
CHAPTER 4
METHODOLGY………………………………………………………………………………...13
4.1 DESIGN AND ANALYSIS…………………………………………………………………14
4.2 CALCULATIONS…………………………………………………………………………...17
CHAPTER 5
EXPERIMENTATION AND RESULTS………………………………………………………..24
CHAPTER 6
CONCLUSION AND FUTURE SCOPE………………………………………………………..28
IV

List of Figures
Figure 4.1 : Wind speed data……………………………………………………….15
Figure 4.2 : Direction wise wind data……….……………………………………...16
Figure 4.3 : Various view of cad model of single blade……………………………18
Figure 4.4 : Various cad views of Coupled Blades…………………………………19
Figure 4.5 : Isometric view of complete assembly…………………………………19
Figure 4.6 : Various views of complete assembly………………………………….20
Figure 4.7 : Vector representation of CFD Result………………………………….21
Figure 4.8 : Shaded and vector representation of CFD Result……………………..21
Figure 4.9 : Complete view of CFD Result Screen………………………………...21
Figure 4.10 : Variation of wind speed along direction of wind…………………...…22
Figure 4.11 : Variation of wind speed perpendicular to the direction of wind………22
Figure 4.12 : Pressure change along direction of wind………………………………23
Figure 4.13 : Pressure change perpendicular direction of wind……………………...23
Figure 5.1 : View of final model……………………………………………………25
Figure 5.2 : View of Dynamo Assembly…………………………………………...25
Figure 5.3 : Velocity of air vs. power developed…………………………………...26
Figure 5.4 : Air velocity vs. efficiency……………………………………………..27
V

LIST OF TABLES
Table 4.1 : Value of cut-in speed, rated wind speed, and cut-out speed……………15
Table 4.2 : Summary of design parameters………………………………………...17
Table 4.3 : Summaries of rotor blade design……………………………………….18
Table 5.1 : Experimentation Result………………………………………………..26
VI

2
INTRODUCTION
If the efficiency of a wind turbine is increased, then more power can be generated thus
decreasing the need for expensive power generators that cause pollution. This would also reduce
the cost of power for the common people. The wind is literally there for the taking and doesn't
cost any money. Power can be generated and stored by a wind turbine with little or no pollution.
If the efficiency of the common wind turbine is improved and widespread, the common people
can cut back on their power costs immensely.
Ever since the Seventh Century people have been utilizing the wind to make their lives easier.
The whole concept of windmills originated in Persia. The Persians originally used the wind to
irrigate farm land, crush grain and milling. This is probably where the term windmill came from.
Since the widespread use of windmills in Europe, during the Twelfth Century, some areas such
as the Netherlands have prospered from creating vast wind farms. The towers without guy wires
are called freestanding towers. Something to take into consideration about a tower is that it must
support the weight of the windmill along with the weight of the tower.
The first windmills, however, were not very reliable or energy efficient. Only half the sail
rotation was utilized. They were usually slow and had a low tip speed ratio but were useful for
torque.
Since its creation, man has constantly tried to improve the windmill. As a result, over the years,
the number of blades on windmills has decreased. Most modern windmills have 5-6 blades while
past windmills have had 4~8 blades. Past windmill also had to be manually directed into the
wind, while modern windmills can be automatically turned into the wind. The sail design and
materials used to create them have also changed over the years.
In most cases the altitude of the rotor is directly proportional to its efficiency. As a matter of fact,
a modern wind turbine should be at least twenty feet above and three hundred feet away from an
obstruction, though it is even more ideal for it to be thirty feet above and five hundred feet away
from any obstruction.
Different locations have various wind speeds. Some places, such as the British Isles, have few
inhabitants because of high wind speeds, yet they are ideal for wind generation. Did you know
that the world's largest wind farm is located in California, and the total wind power generated
there exceeds 1,400 megawatts of electricity? (A typical nuclear power plant generates 1,000
megawatts.)

3
Some geographic features such as mountains also have an influence upon wind. Mountains can
create mountain breezes at night, because of the cooler air flowing down the mountain and being
heated by the warmer valley air causing a convection current. Valleys are affected in much the
same way. In the daytime, the cooler air is above the valleys and the hot air is above the
mountains. The hot air above the mountain rises above the valleys and cools, thus creating a
convection current in the opposite direction and creating a valley wind. The oceans create
convection currents, as well as they mountains or valleys. In the day, the hotter air is above the
same and the cooler air is above the ocean. The air heats up over the sand and rises above the
ocean and then cools, creating the convection current. At night, the cooler air is above the sand
and the warmer air is above the ocean, so the air heats up over the ocean and cools over the sand.
As you can clearly see, the time of day also affects the wind.
We know that for windmills to operate there must be wind, but how do they work? Actually
there are two types of windmills -- the horizontal axis windmills and the vertical axis windmills.
-The horizontal axis windmills have a horizontal rotor much like the classic Dutch four-arm
windmill. The horizontal axis windmills primarily rely on lift from the wind. As stated in
Bernoulli's Principle, "a fluid will travel from an area of higher pressure to an area of lower
pressure." It also states, "as the velocity of a fluid increases, its density decreases." Based upon
this principle, horizontal axis windmill blades have been designed much like the wings of an
airplane, with a curved top. This design increases the velocity of the air on top of the blade thus
decreasing its density and causing the air on the bottom of the blade to go towards the top ...
creating lift. The blades are angled on the axis as to utilize the lift in the rotation. The blades on
modern wind turbines are designed for maximum lift and minimal drag.
1.1 BACKGROUND
Vertical axis windmills, such as the Savonius (built in 1930) use drag instead of lift. Drag is
resistance to the wind, like a brick wall. The blades on vertical axis windmills are designed to
give resistance to the wind and are as a result pushed by the wind. Windmills, both vertical and
horizontal axis, have many uses. Some of them are: hydraulic pump, motor, air pump, oil pump,
churning, creating friction, heat director, electric generator, Freon pump, and can also be used as
a centrifugal pump.
There are many types of windmills, such as: the tower mill, sock mill, sail windmill, water pump,
spring mill, multi-blade, Darrieus, savonis, cyclo-turbine, and the classic four-arm windmill. All
of the above windmills have their advantages. Some windmills, like the sail windmill, are
relatively slow moving, have a low tip speed ratio and are not very energy efficient compared to
the cyclo-turbine, but are much cheaper and money is the great equalizer.

4
There have been many improvements to the windmill over the years. Windmills have been
equipped with air breaks, to control speed in strong winds. Some vertical axis windmills have
even been equipped with hinged blades to avoid the stresses at high wind speeds. Some
windmills, like the cyclo-turbine, have been equipped with a vane that senses wind direction and
causes the rotor to rotate into the wind. Wind turbine generators have been equipped with
gearboxes to control [shaft] speeds. However, Europeans had been experimenting with curved
blades on vertical wind turbines for many decades before this. Wind turbines have also been
equipped with generators which convert shaft power into electrical power. Many of the sails on
windmills have also been replaced with propeller-like airfoils. Some windmills can also stall in
the wind to control wind speed. But above all of these improvements, the most important
improvement to the windmill was made in 1745 when the fantail was invented. The fantail
automatically rotates the sails into the wind.
Most wind turbines start to generate power at 11 m/s and shut down at speeds near 32m/s.
Another variable of the windmill's efficiency is its swept area. The swept area of a disk--shaped
wind wheel is calculated as: Area equals pi times diameter squared divided by four (pi equals
3.14).
Another variable in the productivity of a windmill is the wind speed. The wind speed is
measured by an anemometer. Savonius and other vertical-axis machines are good at pumping
water and other high torque, low rpm applications and are not usually connected to electric
power grids.
Another necessity for a windmill is the tower. There are many types of towers. Some towers
have guy wire to support them and others don't. The towers without guy wires are called
freestanding towers. Something to take into consideration about a tower is that it must support
the weight of the windmill along with the weight of the tower. Towers are also subject to drag.
Scientists estimate that, by the 21st Century, ten percent of the world's electricity will come from
windmills.
1.2 SAVONIUS WIND TURBINE
Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting the
force of the wind into torque on a rotating shaft. The turbine consists of a number of aerofoils,
usually—but not always—vertically mounted on a rotating shaft or framework, either ground
stationed or tethered in airborne systems.

5
The Savonius wind turbine was invented by the Finnish engineer Sigurd Johannes Savonius in
1922. However, Europeans had been experimenting with curved blades on vertical wind turbines
for many decades before this. The earliest mention is by the Italian Bishop of Czanad, who was
also an engineer. He wrote in his 1616 book Machinae novae about several vertical axis wind
turbines with curved or V-shaped blades. None of his or any other earlier examples reached the
state of development made by Savonius. In his Finnish biography there is mention of his
intention to develop a turbine-type similar to the Flettner-type, but autorotationary. He
experimented with his rotor on small rowing vessels on lakes in his country. The Savonius
turbine is one of the simplest turbines.
Savonius turbines are used whenever cost or reliability is much more important than efficiency.
Most anemometers are Savonius turbines for this reason, as efficiency is irrelevant to the
application of measuring wind speed. Much larger Savonius turbines have been used to
generate electric power on deep-water buoys, which need small amounts of power and get very
little maintenance. Design is simplified because, unlike with horizontal axis wind turbines
(HAWTs), no pointing mechanism is required to allow for shifting wind direction and the turbine
is self-starting. Savonius and other vertical-axis machines are good at pumping water and other
high torque, low rpm applications and are not usually connected to electric power grids. They
can sometimes have long helical scoops, to give smooth torque.
The most ubiquitous application of the Savonius wind turbine is the Flettner Ventilator, which is
commonly seen on the roofs of vans and buses and is used as a cooling device. The ventilator
was developed by the German aircraft engineer Anton Flettner in the 1920s. It uses the Savonius
wind turbine to drive an extractor fan. The vents are still manufactured in the UK by Flettner
Ventilator Limited.
Small Savonius wind turbines are sometimes seen used as advertising signs where the rotation
helps to draw attention to the item advertised. They sometimes feature a simple two-
frame animation.
1.3 PRINCIPLE OPERATION
Aerodynamically, it is a drag-type device, consisting of two or three scoops. Looking down on
the rotor from above, a two-scoop machine would look like an "S" shape in cross section.
Because of the curvature, the scoops experience less drag when moving against the wind than
when moving with the wind. The differential drag causes the Savonius turbine to spin. Because
they are drag-type devices, Savonius turbines extract much less of the wind's power than other

6
similarly-sized lift-type turbines. Much of the swept area of a Savonius rotor may be near the
ground, if it has a small mount without an extended post, making the overall energy extraction
less effective due to the lower wind speeds found at lower heights.
1.4 CHARACTERISTICS OF VAWT
Wind Speed
This is very important to the productivity of a windmill. The wind turbine only generates power
with the wind. The wind rotates the axis (horizontal or vertical) and causes the shaft on the
generator to sweep past the magnetic coils creating an electric current.
Blade Length
This is important because the length of the blade is directly proportional to the swept area.
Larger blades have a greater swept area and thus catch more wind with each revolution. Because
of this, they may also have more torque.
Base Height
The height of the base affects the windmill immensely. The higher a windmill is, the more
productive it will be due to the fact that as the altitude increases so does the winds speed.
Base Design
Some base is stronger than others. Base is important in the construction of the windmill because
not only do they have to support the windmill, but they must also be subject to their own weight
and the drag of the wind. If a weak tower is subject to these elements, then it will surely collapse.
Therefore, the base must be identical so as to insure a fair comparison.
1.5 REQUIREMENT OF PLACEMENT
Site Selection considerations
The power available in the wind increases rapidly with the speed; hence wind energy conversion
machines should be located preferable in areas where the winds are strong & persistent. The
following point should be considered while selecting site for Wind Energy Conversion System
(WECS).
High annual average wind speed
The wind velocity is the critical parameter. The power in the wind P
w
, through a given X section
area for a uniform wind Velocity is
P
w
= KV
3
(K is constant)

7
It is evident, because of the cubic dependence on wind velocity that small increases in V
markedly affect the power in the wind
e.g. doubling V, increases P
w
by a factor of 8.
Availability of wind V
(t)
curve at the proposed site
This important curve determines the maximum energy in the wind and hence is the principle
initially controlling factor in predicting the electrical o/p and hence revenue return of the WECS
machines, it is desirable to have average wind speed V such that
V≥12-16 km/hr i.e. (3.5 – 4.5 m/sec).
Wind structures at the proposed site
Wind especially near the ground is turbulent and gusty, & changes rapidly indirection and in
velocity. This departure from homogeneous flow is collectively referred to as ―the structure of
the wind‖.
Altitude of the proposed site
If affects the air density and thus the power in the wind & hence the useful WECS electric power
o/p. The winds tends to have higher velocities at higher altitudes.
Local Ecology
If the surface is bare rock it may mean lower hub heights hence lower structure cost, if trees or
grass or ventation are present. All of which tends to destructure the wind.
Nature of ground
Ground condition should be such that the foundations for WECs are secured, ground surface
should be stable.
Favorable land cost
Land cost should be favorable as this along with other sitting costs, enters into the total WECS
system cost.

9
The Source of Winds
In a macro-meteorological sense, winds are movements of air masses in the atmosphere mainly
originated by temperature differences. The temperature gradients are due to uneven solar heating.
In fact, the equatorial region is more irradiated than the polar ones. Consequently, the warmer
and lighter air of the equatorial region rises to the outer layers of the atmosphere and moves
towards the poles, being replaced at the lower layers by a return flow of cooler air coming from
the Polar Regions. This air circulation is also affected by the Coriolis forces associated with the
rotation of the Earth. In fact, these forces deflect the upper flow towards the east and the lower
flow towards the west. Actually, the effects of differential heating dwindle for latitudes greater
than 30
o
N and 30
o
S, where westerly winds predominate due to the rotation of the Earth. These
large-scale air flows that take place in all the atmosphere constitute the geotropic winds.
The lower layer of the atmosphere is known as surface layer and extends to a height of 100 m. In
this layer, winds are delayed by frictional forces and obstacles altering not only their speed but
also their direction. This is the origin of turbulent flows, which cause wind speed variations over
a wide range of amplitudes and frequencies. Additionally, the presence of seas and large lakes
causes air masses circulation similar in nature to the geotropic winds. All these air movements
are called local winds.
The Power in the Wind
The power in the wind can be computed by using the concepts of kinetics. The wind mill works
on the principle of converting kinetic energy of the wind to mechanical energy. The kinetic
energy of any particle is equal to one half its mass times the square of its velocity,
Kinetic Energy =½ mv
2
.
Amount of Air passing is given by
m = ρ AV …………………..(1)
Where
m = mass of air transversing
A=area swept by the rotating blades of wind mill type generator
ρ = Density of air
V= velocity of air
Substituting this value of the mass in expression of K.E.
= ½ ρ AV.V
2
watts
= ½ ρ AV
3
watts ………………….. (2)
Second equation tells us that the power available is proportional to air density (1.225 kg/m
3
) & is
proportional to the intercept area. Since the area is normally circular of diameter D in horizontal
axis aero turbines, then,

10
A = πD
2
(Sq. m)
4
Put this quantity in equation second then
Available wind power Pa = ρ π D
2
V
3
watt.
8

11
CHAPTER 3
PROBLEM DEFINATION

12
The development of vertical axis wind turbines can be traced back to 300 – 900 A.D. where
these were utilized for grain grinding and water pumping processes. VAWTs offer a number of
advantages over traditional horizontal-axis wind turbines (HAWTs). They can be packed closer
together in wind farms, allowing more in a given space. They are quiet, Omni-directional, and
they produce lower forces on the support structure. They do not require as much wind to
generate power, thus allowing them to be closer to the ground where wind speed is lower. By
being closer to the ground they are easily maintained and can be installed on chimneys and
similar tall structures.
Research at Caltech has also shown that carefully designing wind farms using VAWTs can result
in power output ten times as great as a HAWT wind farm the same size.
VAWTs are much quieter than HAWTs, with dB levels at ground level ten meters from the
tower measured at around 95 dB for a HAWT versus 38dB for a VAWT. This is due to several
factors, starting with the much lower tip speed of VAWTs.
However most of the above claims are considered debatable by people with experience of wind
engineering such as Paul Gipe, Mick Sagrillo and most of the active installers. There is very little
history of successful VAWT operation, despite their long history.
Thus in this project we aim to carefully design, analyze, fabricate and calculate the performance
of a Vertical axis wind turbine to determine problems with these turbines and attempt to suggest
some solution to the determined problem.

14
4.1 Design Methodology
Wind power, Pw is defined as the multiplication of mass flow rate, ρAV and the kinetic energy
per unit mass, ½ V2
(Musgrove, 2010). The wind power is denoted by the equation of:
Pw = ½ ρAV3
(1)
Hayashi, et al. (2004) found that the swept area for Savonius Wind Turbine is calculated by
multiplication of rotor diameter, D and the rotor height, H. The larger the swept area, the larger
the power generated.
A = D.H (2)
The wind power in Equation (3) represents the ideal power of a wind turbine, as in case of no
aerodynamic or other losses during the energy conversion processes. However, as stated by
Manwell et al., (2009) there is not possible for all energy being converted into useful energy. The
ideal efficiency of a wind turbine is known as Betz limit. According to the Betz limit, as
supported by Musgrove (2010) there is at most only 59.3 % of the wind power can be converted
into useful power. Some of the energy may lose in gearbox, bearings, generator, transmission
and others (Jain, 2011). The maximum power coefficient, Cp for Savonius rotor is 0.30. Hence,
the Cp value used in this project is 0.30 and the power output, P with considering the power
efficiency is:
P = 0.15 ρAV3
(3)
4.2 Parameters
Wind speed is the major element that affects the power output. The three wind speed parameters
involve in this project is cut-in speed, rated wind speed and cut-out speed. Jain (2011) stated that
the three wind speed parameters related to the power performance are as follow:
Vcut-in = 0.5 Vavg (4)
VRated = 1.5 Vavg (5)
Vcut-out = 3.0 Vavg (6)

15
All these parameters depend on the value of average wind speed. The average wind speed, Vavg
was found by gathering the data of wind speed from march 2013 to feburary 2014 from
windfinder.com website and the average wind speed was found to be 3m/s in Indore. Table 1
summarizes the value of these three wind speed parameters.
Table 4.1: Value of cut-in speed, rated wind speed, and cut-out speed.
Wind Speed Parameter Equation Calculation
Cut-in speed, Vcut-in Vcut-in = 0.5 Vavg 1.5 m/s
Rated wind speed, VRated VRated = 1.5 Vavg 4.5 m/s
Cut-out speed, Vcut-out Vcut-out = 3 Vavg 9 m/s
4.3 Selection
Aspect ratio is a crucial criterion to evaluate the aerodynamic performance of Savonius rotor.
Johnson (1998) suggests the Savonius rotor is designed with rotor height twice of rotor diameter
and this lead to better stability with proper efficiencies.
Figure 4.1: Wind Speed data of Indore

16
Aspect ratio is a crucial criterion to evaluate the aerodynamic performance of Savonius rotor.
Johnson (1998) suggests the Savonius rotor is designed with rotor height twice of rotor diameter
and this lead to better stability with proper efficiencies.
AR = H/D (7)
Tip speed ratio, λ is defined as the ratio of the linear speed of rotor blade ω.R to the undisturbed
wind speed, V (Solanki, 2009). ω is the angular velocity and R represent the radius revolving
part of the turbine. The maximum tip speed ratio that Savonius rotor can reach is 1. Manwell et
al., (2009) write that high tip speed ratio improves the performance of wind turbine and this
could be obtained by increasing the rotational rate of the rotor.
λ = ω.R /V (8)
Figure 4.2: Direction wise wind data

17
According to Manwell et al., (2009) solidity is related to tip speed ratio. A high tip speed ratio
will result in a low solidity. Musgrove (2010) defines solidity as the ratio of blade area to the
turbine rotor swept area. For VAWT, the solidity is defined as
σ = nd /R (9)
Where n is the number of blades, d is the chord length or can be defined as the diameter of each
half cylinder, and R is radius of wind turbine. Many researchers have proved that the higher the
number of blades, the higher the performance of most wind turbine. However, Saha et al., (2008)
and Zhao et al., (2009) found that the two-bladed Savonius rotor has higher performance than
three-bladed Savonius rotor. Referring to Saha then the two-blade rotor has been chosen for this
project. Table 3.2 shows the design parameters used in this research.
Table 4.2: Summary of design parameters.
Parameter Value
Power Available in the wind 17 W
Swept Area 0.31 m2
Rated Wind Speed 4.5 m/s
Aspect Ratio 1.2
Tip Speed Ratio 1.0
Solidity 2.114
Diameter – Height 0.51 m – 0.61 m
Number of Blade 2
4.4 Design specification.
The design of the Savonius rotor blade is shown in Figure 2, while Table 3 shown the detail
dimension of the Savonius rotor blade. The material proposed for the Savonius rotor blade in this
project is Aluminium.

18
Table 4.3: Summaries of rotor blade design and the material properties of Aluminum.
Parameter Value
Swept Area, A 0.31 m2
Rotor Diameter, D 510 mm
Rotor Height, H 610 mm
Chord Length, d 260 mm
Overlap Distance, e 101.6 mm
Blade Thickness, t 1 mm
Density 2700kg/m3
Young’s modulus 0.69 GPa
Poisson’s ratio 0.33
Tensile yield strength 276MPa
Analysis
CAD model of Savonius blade and assembly was done using Caria v5 for the purpose of
Computational fluid Dynamics analysis and to simplify fabrication process
Below the figure shows various views of the CAD model of Savonius blades and the overall
assembly

19
The above picture is a clip of Savonius blade taken from Catia v5 software. The blade were
modeled in catia v5 to exact dimension as produced above in design to visualize actual size of
the model and for proper assembly.
The next Figure below shows the combine geometry of the blades after combining the two
blades this model was used for CFD analysis of the model to produce reliable results as the
models were of actual size. Complete assembly was modeled in Catia V5 software as shown in
pictures below.
Figure4.4: Various cad views of Coupled Blades
Figure4.5: Isometric view of complete assembly

20
Computational fluid dynamics
Air flow around the turbine was simulated using Autodesk Simulation CFD 2014 this was done
to understand the flow around the turbine and understand the variation in wind speed in various
regions around.
For visualization of flow and Variation in wind speed, the inlet air velocity was set at 5m/s
second and static zero gauge pressure. The flow pattern and variation as observed are shown
below in the following pictures
The flow pattern observed were as expected wind deep blue regions near the blades surface
shows the boundary layer formation and the bend of air around the blades and through the
overlap region. The contour plot analysis gives an idea about the flow physics of a wind rotor.
The contour plot analysis gives an idea about the flow physics of a wind rotor and its power
production mechanism. In the present study, relative velocity magnitude (velocity of the rotor
relative to wind) and static pressure contours of the Savonius rotor are analysed. The contour
plots are obtained for tip speed ratio at which power coefficient of the rotor is the highest for
each overlap condition. Picture show the relative velocity contours of the two-bucket Savonius
rotor for overlap conditions of 12.37%, The relative velocity magnitude contours show that there
is a decrease of relative velocity magnitude from the upstream side to the downstream side of the
rotor. Fig. 6(a) for 12.37% overlap shows that relative velocity decreases from upstream to
downstream across the rotor.
Figure 4.6: Various views of complete assembly

21
Figure 4.7: Vector representation of
CFD Result
Figure 4.8: Shaded and vector representation
of CFD Result
Figure 4.9: Complete view of CFD Result Screen

22
Figure 4.10: Variation of wind speed along the direction of wind through the Savonius
blade
Figure 4.12: Pressure change along direction of wind

23
Figure 4.11: Variation of wind speed perpendicular to the direction of
wind
Figure 4.13:Pressure change perpendicular direction of wind

24
CHAPTER 5
EXPERIMENTATION AND RESULT.

25
Model
The model of the Savonius turbine was made in college workshop. Pictures of model are shown
below. To get electrical power output a DC motor was used inversely with Savonius input
connected to motor shaft and electrical output taken from terminals of the motor. This energy
was used to charge battery and thus making the model a reliable source of continuous energy.
Figure 5.1: View of final model
Figure 5.2: view of Dynamo Assembly

26
Observations.
To test the model at different speeds an external fan was used to generate the desired speed of
wind and then electrical power generated was determined using a multi-meter. From thus
accumulated data the efficiency of the turbine was determined.
RPM
Velocity of air in
m/s
Power available power
(watts) VI (watts) Efficiency
46 0.1175 0.069 0.0103 14
54 0.877 0.124 0.018 15
67 1.036 0.209 0.032 15.5
75 1.19625 0.3245 0.051 16
83 1.355 0.466 0.0745 16
98 1.595 0.776 0.124 16.9
118 1.915 1.941 0.226 17
163 2.553 3.143 0.55 17.5
188 3.05 5.17 0.939 18.18
223 3.58 8.699 1.54 17.8
0
0.5
1
1.5
2
2.5
3
3.5
4
VI 0.0103 0.018 0.032 0.051 0.0745 0.124 0.226 0.55 0.939
Velocityofairinm/s
Figure 5.3Velocity of air vs Power developed
Table 5.1 Experimentation Result

27
Efficiency of the model was variable with wind speed with maximum of 18.18% in the region of
wind speed produced by the fan.
0
2
4
6
8
10
12
14
16
18
20
Efficiencyin%
Figure 5.4: Air velocity vs Efficiency

28
CHAPTER 6
CONCLUSION AND FUTURE SCOPE

29
Conclusion
The efficiency of the fabricated wind turbine was found to be around 18 percent with variation at
different velocities of the wind. Though the efficiency seems quite low but It can be seen as
usable power generated from nothing. These turbines have a great advantage over Horizontal
axis wind turbine that they can work on low height thus these turbines can be installed on
individual houses for their particular use. The power generated from the turbine can be stored or
used to charge a storage device and then the storage device can be used as a continuous power
source. Having said that there are some limitation of these turbines VAWT blades are rarely at
an optimal angle to the wind or in clean air, so they can never be as efficient as a tripled HAWT
and won’t generate more electricity, HAWTs almost never collapse due to lateral stress, and
VAWTs typically have very asymmetrical front and rear stresses on their bearings, and To
generate the same electricity, VAWTs would have to be as tall as HAWTs, so visual impact will
be virtually identical.
Yet with more and more engineers and researchers working on the design and development of
Vertical axis wind turbine the efficiency can be increased and the usability of these turbines can
be increased.
Future Consideration
Due to the large variations in testing data, additional testing is required. This testing should focus
on the following key areas to improve testing results:
Data Acquisition System– Increase the sampling frequency of the DAQ to allow for a more
accurate reading of the rotational speed of the shaft. Increasing the sample rate will permit the
use of a LED sensor that can count the number of rotations made by the turbine.
Braking Mechanism– The friction brake presented problems in pulse loading. It should be
determined if the use of an eddy current is feasible. Alternatively, a friction brake more suited to
the current testing methods can be acquired and used.
Additional considerations to validate or invalidate this particular design include:

30
Install a small generator– Connect the turbine to a small generator to determine the power
output of the entire system. This particular study focused on the blade performance but the full
concept should include the total system efficiency.
Reliability Testing– Testing of the turbine should be conducted under various weather
conditions to determine the reliability of the turbine. This turbine should be subjected fully
developed and turbulent winds under icing and snowing conditions. The components should also
undergo longer term reliability testing when subjected to Newfoundland’s environment.

31
REFERENCES.
 Becker, W. S. ―Wind Turbine Device.‖ US Patent # 7,132,760 B2. Filed (Jul. 29, 2003).
 Benesh, A. ―Wind Turbine System Using Twin Savonius-Type Rotors.‖ US Patent #
4,830,570. Filed (Dec. 15, 1987).
 Bertony, J. ―Vertical Axis Wind Turbine with Twisted Blade or Auxiliary Blade.‖ US
Patent Application # 2008/0095631 A1. Filed (Oct. 19, 2005).
 Cleanfield Energy. V3.5 ―Vertical Axis Wind Turbine System: Product Overview and
Key Benefits‖. Retrieved From:
http://www.cleanfieldenergy.com/site/sub/p_we_overview.php.
 Cooper, P. & Kennedy, O. ―Development and Analysis of a Novel Vertical Axis Wind
Turbine‖. University of Wollongong. Filed (March, 2003).
 Savonius, S. J. Wind Rotor. US Patent #1,766,765. Filed (Oct. 11, 1928).
 Mario Pozner, ―Early history through 1875‖ Retrieved From:
http://telosnet.com/wind/early.html
 Mike Bernard, ―Why aren’t vertical-axis wind turbines more popular?‖ Retrieved From:
http://barnardonwind.com/2013/02/23/why-arent-vertical-axis-wind-turbines-more-
popular/
 James F. Manwell, Jon G. McGowan, Anthony L. Rogers ―Wind Energy Explained:
Theory, Design and Application‖ December 2009: published by: Wiley.
 Ion Paraschivoiu ―Wind Turbine Design: With Emphasis on Darrieus Concept‖, Presses
inter Polytechnique, 2002

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