LOW EXPENSE VERTICAL AXIS WIND TURBINE USING … · Low Expense Vertical Axis Wind Turbine Using Permanent Magnets

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International Journal of Mechanical Engineering and Technology (IJMET)

Volume 7, Issue 2, March-April 2016, pp. 244–260, Article ID: IJMET_07_02_026

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LOW EXPENSE VERTICAL AXIS WIND

TURBINE USING PERMANENT MAGNETS

Ramu S

Assistant Professor

Sree Narayana Institute of Technology, Adoor, Kerala

Abhilash M, Ajay M, Aravind S, Hariprasad M

Students, Sree Narayana Institute of Technology,

Adoor, Kerala

ABSTRACT

Wind turbines are devices that convert the wind's kinetic energy into

electrical power. The result of over a millennium of windmill development and

modern engineering, today's wind turbines are manufactured in a wide range

of horizontal axis and vertical axis types. The smallest turbines are used for

applications such as battery charging for auxiliary power. Slightly larger

turbines can be used for making small contributions to a domestic power

supply while selling unused power back to the utility supplier via the electrical

grid. Arrays of large turbines, known as wind farms, have become an

increasingly important source of renewable energy and are used in many

countries as part of a strategy to reduce their reliance on fossil fuels.

Key word: Design, Material Selection, Modelling, Analysis

Cite this Article Ramu S, Abhilash M, Ajay M, Aravind S and Hariprasad M,

Low Expense Vertical Axis Wind Turbine Using Permanent Magnets.

International Journal of Mechanical Engineering and Technology, 7(2), 2016,

pp. 244–260.

http://www.iaeme.com/currentissue.asp?JType=IJMET&VType=7&IType=2

1. INTRODUCTION

When 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. Windmills have 5-6 blades. While past

windmills have had 48 blades. Past windmill also had to be manually directed into the

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Low Expense Vertical Axis Wind Turbine Using Permanent Magnets


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 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. Some geographic features such as mountains also have

an influence upon wind. Mountains can create mountain breezes at night, because of

the cooler air owing 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. 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

wind-mill. 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. Vertical axis

windmills, such as the Durries (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. 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 cycloturbine, 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. 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 aerofoils. 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 disc 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. Another necessity for a windmill is the tower. There are many types of

Ramu S, Abhilash M, Ajay M, Aravind S and Hariprasad M


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.

2. SCOPE OF WORK

To utilize the available wind resources and to reduce the usage of non-renewable

energy resources. Wind energy is by far the fastest-growing renewable energy

resource. The wind energy industry so far has been supported by market incentives

backed by government policies fostering sustainable energy resources. Large-scale

wind facilities approaching the output rating of conventional power plants, control of

the power quality is required to reduce the adverse effects on their integration into the

network. These wind turbines can be used to provide constant lighting. Building’s

rooftops can be an excellent location for this type of wind mill, both because the

electric power generation is close to the user and because they allow taking

advantages of faster winds and also it is possible for generating power in rural areas

and hilly tops where electric transmission lines are difficult to reach. It can be

installed in more locations like highways, in parking areas etc.

3. LITERATURE REVIEW

The forces and the velocities acting in a Darrieus turbine are depicted. The resultant

velocity vector W, is the vectorial sum of the undisturbed upstream air velocity U, and

the velocity vector of the advancing blade. Types of vertical axis wind turbines are as

follows.

3.1. Darrieus Wind Turbine

Commonly described as “Eggbeater” turbines, or Darrieus turbines, were named after

the French inventor, Georges Darrieus. They have good efficiency, but produce large

torque ripple and cyclical stress on the tower, which contributes to poor reliability.

They also generally require some external power source, or an additional Savonius

rotor to start turning, because the starting torque is very low. The torque ripple is

reduced by using three or more blades which results in greater solidity of the rotor.

Solidity is measured by blade area divided by the rotor area. Newer Darrieus type

turbines are not held up by guy-wires but have an external superstructure connected to

the top bearing. The Darrieus design, the aerofoils are arranged so that they are

symmetrical and have zero rigging angle, that is, the angle that the aerofoils are set

relative to the structure on which they are mounted. This arrangement is equally

effective no matter which direction the wind is blowingin contrast to the conventional

type, which must be rotated to face into the wind. When the Darrieus rotor is

spinning, the aerofoils are moving forward through the air in a circular path. Relative

to the blade, this oncoming airflow is added vectorially to the wind, so that the

resultant airflow creates a varying small positive angle of attack to the blade. This

generates a net force pointing obliquely forwards along a certain ’line-of- action’.

This force can be projected inwards past the turbine axis at a certain distance, giving a

positive torque to the shaft, thus helping it to rotate in the direction it is already

travelling in. The aerodynamic principles which rotate the rotor are equivalent to that

in autogiros, and normal helicopters in autorotation. As the aerofoil moves around the

back of the apparatus, the angle of attack changes to the opposite sign, but the

generated force is still obliquely in the direction of rotation, because the wings are

symmetrical and the rigging angle is zero. The rotor spins at a rate unrelated to the



windspeed, and usually many times faster. The energy arising from the torque and

speed may be extracted and converted into useful power by using an electrical

generator. The blades of a Darrieus turbine can be canted into a helix, e.g. three

blades and a helical twist of 60 degrees, similar to Gorlov’s water turbines The

aeronautical terms lift and drag are, strictly speaking, forces across and along the

approaching net relative airflow respectively, so they are not useful hereUnder rare

conditions, Darrieus rotors can self-start, so some form of brake is required to hold it

when stopped. A Darrieus wind turbine used to generate electricity on the Magdalen

Islands Giromill A subtype of Darrieus turbine with straight, as opposed to curved,

blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and

is self-starting.The advantages of variable pitch are: high starting torque; a wide,

relatively flat torque curve; a lower blade speed ratio; a higher coefficient of

performance; more efficient operation in turbulent winds; and a lower blade speed

ratio which lowers blade bending stresses. Straight, V, or curved blades may be used.

Giromill VAWTs are also self-starting.

Figure 1 Orking of Darrieus Wind Turbine

3.2. Savonius Wind Turbine

Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-

type devices, 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 the drag when moving against the wind

than when moving with the wind. The differential drag causes Savonius turbine to

spin. Because they are drag-type devices, Savonius turbines extract much less of the

wind’s power than other 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.

3.3. Advantages of Savonius Turbines

Savonius turbines are used whenever cost or the reliability is much more important

than efficiency. For example, most anemometers are Savonius turbines, because

efficiency is completely irrelevant for that application. 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. 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.

4. CHARACTERSTICS AND SPECIFICATIONS OF WIND

TURBINES

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 warm 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 defect the upper flow towards the east and the lower flow

towards the west. Actually, the effects of differential heating dwindle for latitudes

greater than 30ºN and 30ºS, 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 geostrophic 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 geostrophic winds. All these air movements are

called local winds.

4.1. The Power of 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.

4.2. 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.



4.3. 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

4.4. 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.

4.5. 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.

Figure 2 Block Diagram of Vertical Axis Wind Turbine

5. INDIAS MARKET OVERVIEW OF WIND ENERGY

OVERVIEW

The development of wind power in India began in the 1990s, and has significantly

increased in the last few years. Although a relative newcomer to the wind industry

compared with Denmark or the US, India has the fifth largest installed wind power

capacity in the world. In 2009-10 India’s growth rate is highest among the other top

four countries. The worldwide installed capacity of wind power reached 157,899 MW

by the end of 2009. USA (35,159 MW), Germany (25,777 MW), Spain (19,149 MW)

and China (25,104 MW) are ahead of India in fifth position. The short gestation

periods for installing wind turbines, and the increasing reliability and performance of

wind energy machines has made wind power a favoured choice for capacity addition

in India. India has a vast supply of renewable energy resources. India has one of the

world’s largest programs for deployment of renewable energy products and systems

3,700 MW from renewable energy sources installed.



Table I Capacity of Indias Wind Powerplants

States with potential Potential MW Installed MW

Andra Pradesh 8285 93

Gujarat 9675 173

Madya Pradesh 5500 23

Maharashtra 3650 401

Orissa 1700 1

Karnataka 6620 124

Rajastan 5400 61

Tamil Nadu 3050 990

West Bengal 450 1

6. MATERIALS USAGE IN CURRENT WIND TURBINES

A wide range of materials are used in wind turbines. There are substantial differences

between small and large machines and there are projected changes in designs that will

accommodate the introduction of new material technologies and manufacturing

methods. To arrive at a total, the material usage is weighted by the estimated market

share of the various manufacturers and machines types. In general the materials used

for wind turbines are Steel, Aluminium, Copper and PVC Pipes In this project we

have used Aluminium discs and PVC Pipes. The following are certain important

properties present in the materials.

6.1. Young’s modulus

Its defined as the ratio of stress and strain, where the strain does not have units.

Therefor youngs modulus has the units of stress, N/mm2 , MPa , GPa The value for

PVC is 10 GPa.

6.2. Hooke’s law

This law states that stress is directly proportional to strain within the elastic limit.

Yield stress it is the value of stress at which the material continues to deform at

constant load conditions. The value for PVC Pipe is 20MPa.

6.3. Ultimate stress

It is the maximum stress induced in the specimen and it occurs in the plastic region.

The value for PVC Pipe is 6.89 MPa.

6.4. Fracture Stress

As the reduction in cross sectional area continues, the load bearing capacity of

specimen reduces gradually. At a certain stage cross sectional of specimen is so small

that it cannot sustain the load and hence it breaks. The stress at which the specimen

breaks is known as fracture stress. It is generally less than ultimate stress for ductile

and plastics materials.

6.5. Hardness

It is the measure of resistance to penetration and abrasion, which is a function of

stress required to produce some specified type of failure. It is generally expressed as a

number. Toughness The ability of material to absorb energy in the plastic range is



known as toughness. Toughness per unit volume of the material is known as modulus

of toughness.

7. PRINCIPLE OF GENERATOR OPERATION

7.1. Generator

The generator uses rotating coils of wire and magnetic fields to convert mechanical

rotation into a pulsing direct electric current through Faraday’s law of induction. A

dynamo machine consists of a stationary structure, called the stator, which provides a

constant magnetic field, and a rotating winding called armature which turn within that

field. The motion of the wire within the magnetic field causes the field to push on the

electrons in the metal, creating an electric current in the wire. On small machines

constant magnetic field may be provided by one or more permanent magnets; larger

machines have constant the magnetic field provided by one or more electromagnets,

which are usually called field coils. The commutator was needed to produce direct

current. When a loop wire rotates in a magnetic field, the potential induced in it

reverses with each half turn generating an alternating current. However, in early days

of electric experimentation, alternating current generally no known use. The few uses

for electricity, such as electroplating, used direct current provided by messy liquid

batteries. The generation of electricity by a dynamo is based on a principle of

magnetism called induction. When the lines of force that pass from the north to the

south pole of a magnet are cut by a wire there is produced or induced in the wire a

current of electricity. That is, if we take a loop or coil of wire which has no current in

it and a magnet which also has no current, and move the loop or coil between the

poles, a momentary current is produced. If a series of loops or coils are used instead

of one loop, a current may be generated continuously. This method of generating

electric current is called induction.

Figure 3 Magnetic Field Showing Loop of Wire Rotating Between the North (N) and South

(S) Poles of A Magnet

7.2. Direction of an Induced Current

The direction of an induced current depends upon two factors: (1) the direction of the

motion of the wire, and (2) the direction of the magnetic lines of force. A very

valuable method of determining the direction of current used in practical life is called

Fleming's Rule. Place the thumb, forefinger, and center finger of the right hand so as

to form right angles to each other. If the thumb points in the direction of the motion of

the wire, and the fore finger in the direction of the magnetic lines of force, the center

finger will point in the direction of the induced current. It is very important to know



the direction of the current in revolving a loop of wire between the poles of a magnet

in order to understand the working of a generator. The loop of wire between the poles

of the magnet. If the loop is rotated to the right, as indicated by the arrow head, the

wire XB moves down during the first half of the revolution. As the result of the first

half of the revolution, the current would flow in the direction AYBX. Repeat the

reasoning for the second half of the revolution. Notice that for every complete

revolution, the current reverses its direction twice. As the strength of the current

depends upon the number of lines of force cut, so the induced electromotive force

starts at zero, goes to a maximum, and then back to zero in the first half-turn. That is,

the induced electromotive force reaches its maximum when the loop is in a horizontal

position because it cuts the most lines of force at this position. It cuts the least number

of lines of force at the beginning and at the end of each half-vertical revolution.

8. DESIGN OF WIND TURBINE

8.1. Design of Blade

Wind turbine blades have on aero foil type cross section and a variable pitch. While

designing the size of blade it is must to know the weight and cost of blades. In the

project nine blades with vertical shaft are used, it has a height and width of 100cm

and 6inch respectively. So if one Blade moves other blades comes in the position of

first blade, so the speed is increases. Since we are making a low cost wind turbine, the

blades are made using PVC pipes.

Figure 4 Design of Blades

8.2. Shaft Designing

While designing the shaft of blades it should be properly fitted to the blade. The shaft

should be as possible as less in thickness and light in weight for the nine blade, the

shaft used is very thin in size are all properly fitted. So no problem of slipping and

fraction is created, we are cycle rims at the top and bottom side they are easily

available, cheap and works perfectly. Length of shaft is 1m.



Figure 5 Shaft Designing

8.3. Design of Bearing

For the smooth operation of Shaft, bearing mechanism is used. To have very less

friction loss the two ends of shaft are pivoted into the same dimension bearing. The

Bearing has diameter of 2.54cm. Bearing are generally provided for supporting the

shaft and smooth operation of shaft. We have used ball bearings for the purpose of

ease of maintenance.

8.4. An Electric Dynamo

For generation of electricity from the designed our vertical axis wind turbine, we

chose generator that can be made by our surrounding materials. We select an old

ceiling fan, since it have the windings in it. We remove the rotating aluminium disk ie

the rotor and placed permanent magnets (neodymium) between the air gaps.14

magnets were placed according to the coils and closed the fan.

Figure 6 Ceiling Fan with Magnet Placed



Table 2 Specification of Vertical Axis Wind Turbine

Base Dimension

Height 100cm

Width 150cm

Blade Dimensions

Height 100cm

Diameter 6 in

Thickness 0.125 in

Angle between blades 40 degrees

Shaft Dimension

Diameter 2.54cm

Length 100cm

9. OPERATIONS INVOLVED IN FABRICATION PROCESS

9.1. Gas Cutting

A cutting torch is used to heat metal to kindling temperature. A stream of oxygen is

then trained on the metal and metal burns in that oxygen and then flows out of the cut.

For cutting, the set-up is a little different. A cutting torch has a 60- or 90-degree

angled head with orifices placed around a central jet. The outer jets are for preheat

flames of oxygen and acetylene. The central jet carries only oxygen for cutting. The

use of a number of preheating flames, rather than a single flame makes it possible to

change the direction of the cut as desired without changing the position of the nozzle

or the angle which the torch makes with the direction of the cut, as well as giving a

better preheat balance . Manufacturers have developed custom tips for Map, propane,

and polypropylene gases to optimize the flames from these alternate fuel gases.

9.2. ARC Welding

Arc welding uses a welding power supply to create an electric arc between an

electrode and the base material to melt the metals at the welding point. They can use

either direct (DC) or alternating (AC) current, and consumable or non-consumable

electrodes. The welding region is sometimes protected by some type of inert or semi-

inert gas, known as a shielding gas, and/or an evaporating filler material. The process

of arc welding is widely used because of its low capital and running costs. The

following gauge lengths of electrodes are used in this process 8, 10 and 12mm. The

number of electrodes used in this fabrication is around 40-45 electrodes.

9.3. Aluminium Welding

Welding of aluminium is easily done and only requires a little extra equipment and

skills. Extra equipment will be needed no matter what and if welding out of position it

will require a journeyman skill level (that’s an understatement). Aluminium welds

very well with MIG and it is best used on thicker materials that are in the flat position.

You can weld thinner materials and out of position but those areas are only for the

highly skilled and experienced aluminium MIG Welders. In most cases even if you

are an experienced welder this is going to be very difficult to learn because of the way

the puddle looks and the fast travel speeds used to weld out of position.



10. OPERATIONS MODELING OF VAWT

The modelling of VAWT prototype is carried out in solid edge ST6, and this should

be helpful in predict the failure of wind turbine at various load. The different parts of

VAWT are shown in below.

10.1. Wind turbine

The VAWT consists of nine blades of PVC sectioned pipes and has a diameter of 15

cm and a length of 1 m. As we consider about the weight it is the most efficient

material that satisfies both strength and light weight with minimum cost. The nine

blades are attached to the cycle rim with the help of nut and bolt. The rotation of the

turbine is transmitted to the generator and power is generated. The turbine has the

capacity to withstand 9.8 m/s velocity of wind. Since the power developed in wind

turbine is directly proportional to cubic times of velocity of air and area of blades.

Figure 7 Wind Turbine

10.2. Joining between Blades and Rim

The blades are attached to the rim though the nut and bolt. The bolts has length of 30

mm and 10mm diameter. Each blades consists of 8 nut and bolt joints. The nut and

bolts are attached to the rim with help of a 3mm thickness metal plate.



Figure 8 Joining Between Blades and Rim

10.3. Pulley

A driven pulley is attached on the top of the generator. The driven pulley has a

diameter of 10 cm and the driver pulley has a diameter of 6cm. the center to center

distance between the pulley and turbine is made adjustable and we take the mean

distance as 90cm. there is also a mechanism for adjusting the height of the generator

through a lever mechanism.

Figure 9 Pulley



10.4. Belt Drive

There is a belt drive that connected between the wind turbine and the driven pulley

that is connected with the generator. Round belt is used as the transmission drive,

because the area of contact is minimum and high efficient and cost effective. The

length of the belt is 296 cm which can be find from the below equation.

L= π (r1 + r2) + 2x + [(r1 – r2)2/x] (1)

Where x = center to center distance between the driver and the driven pulley.

The angle of contact of the assembly is 147.76 degree which can be calculated

from the below equation.

Ø = (180 - 2α) π/180 (2)

Figure 10 Belt drive

11. THEORTICAL CALCULATIONS

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, or mv2

K.E = mv2 (3)

K.E = kinetic energy

m = mass

v = velocity M is equal to its Volume multiplied by its density of air

M = AV (4)

Substituting equation (4) in equation (3) we get

KE = AV.V 2

KE = AV 3 watts

P= ρAV3 / 2 (5)

P= power of the turbine ρ= density of air (1.225 kg/m3)

A= Area of air in m2

V= Velocity of striking air m/s

A = length*breadth (m2)

A = πDL/2 (6)



D = Diameter of the blade (m

L = Length of the blade (m)

12. ANALYSIS OF VAWT

Analysis of wind turbine blades are conducted in solid edge ST6. It gives maximum

stress that can withstand , and the deflection diagram at maximum principle stress.

Analysis conducted on blade material gives positive results.

12.1. Result of Analysis

(a) The optimum power is generated when the wind is blow at 4 to 5m per second and

deflection is minimum at this speed. The stress value that develop in the joining

portion is found to be the maximum and its value is 5.65 MPa. Which is less than the

ultimate stress.

(b) The failure of the turbine blades occur , when the wind blows at a speed of 9.8 m/s

and the deflection of the blades are maximum and the von misses stress is 6.9 MPa.

At this condition a cracking on the joining face of the blades will occur.

Figure 11 Analysis of Blades

13. STORAGE SYSTEM

13.1. Inverter

A power inverter, or inverter, is an electronic device or circuitry that changes direct

current (DC) to alternating current(AC) The input voltage, output voltage and

frequency, and overall power handling depend on the design of the specific device or

circuitry. The inverter does not produce any power; the power is provided by the DC

source. A power inverter can be entirely electronic or may be a combination of

mechanical effects (such as a rotary apparatus) and electronic circuitry. Static

inverters do not use moving parts in the conversion process

13.2. Batteries

The runtime of an inverter is dependent on the battery power and the amount of power

being drawn from the inverter at a given time. As the amount of equipment using the

inverter increases, the runtime will decrease. In order to prolong the runtime of an

inverter, additional batteries can be added to the inverter. Battery used for this

construction is Lead Acid Battery.



Figure 11 Block Diagram For The Battery And Inverter Setup

14. ADVANTAGE OF VERTICAL AXIS WIND TURBINE OVER

HORIZONTAL AXIS WIND TURBINE

There are several reasons why we would choose a vertical axis wind turbine over

a horizontal axis windmill.

1. They are mounted lower to the ground making it easy for maintenance if needed

2. They start creating electricity at speeds of only 6 mph.

3. They may be able to build at locations where taller structures, such as the horizontal

type can’t

4. Higher power utilization

5. Lower noise level–only 27-37 DB, suitable for your living condition.

6. Safer operation–Spin at slower speeds than horizontal turbines, decreasing the risk of

Injuring birds and also decreasing noise level.

7. Simpler installation and maintenance– besides the traditional installation site, it can

be Mounted directly on a rooftop, doing away with the tower and associated guy

lines.

8. Not affected by orientation variation no matter the wind blow from any orientation,

VAWT can work without regard to its face. Economical and practical-Although one-

time investment expenses are larger, but you don’t have to pay higher tariffs forever.

15. CONCLUSION

Our work and the results obtained so far are very encouraging and reinforce the

conviction that vertical axis wind energy conversion systems are practical and

potentially very contributes to the production of clean renewable electricity from the

wind even under less than ideal sitting conditions. It is hoped that they may be

constructed used high-strength, low- weight materials for deployment in more

developed nations and settings or with very low tech local materials and local skills in

less developed countries. The Savonius wind turbine designed is ideal to be located on

top of a bridge or bridges to generate electricity, powered by wind. The elevated

altitude gives it an advantage for more wind opportunity. With the idea on top of a

bridge, it will power up street lights and or commercial use. In most cities, bridges are

a faster route for everyday commute and in need of constant lighting makes this an

efficient way to produce natural energy.

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