2. INTRODUCTION TO WIND POWER
The power in the wind can be computed by using the concepts of kinetics. The kinetic energy of any
particle is given by the following formula
Kinetic Energy =½ mv2.
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.V2 watts
= ½ ρ AV3 watts ………………….. (2)
Second equation tells us that the power available is proportional to air density (1.225 kg/m3)
is proportional to the intercept area. Since the area is normally circular of diameter D in horizontal
axis aero turbines, then,
A = 0.25πD2 (Sq. m)
Put this quantity in equation second then
Available wind power Pa =0.125 ρ π D2 V3 watt
4. VERTICAL AXIS WIND TURBINE
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, giromill and
cycloturbine) included the pulsatory torque that can be produced during
each revolution and the huge bending moments on the blades. Later designs
solved the torque issue by using the helical twist of the blades almost
similar to Gorlov's water turbines.
A VAWT tipped sideways, with the axis perpendicular to the
wind streamlines, functions similarly. A more general term that includes
this option is "transverse axis wind turbine". For example, the original
Darrieus patent , includes both options.
Drag-type VAWTs, such as the Savonius rotor, typically operate
at lower tipspeed ratios than lift-based VAWTs such as Darrieus rotors and
cycloturbines.
6. DARRIEUS WIND TURBINE
The Darrieus wind turbine is a type of vertical axis wind turbine (VAWT)
used to generate electricity from the energy carried in the wind. The turbine
consists of a number of aerofoils usually—but not always—vertically mounted
on a rotating shaft or framework.
DARRIEUS WIND TURBINE WORKING METHODOLOGY
7. GIROMILL WIND TURBINE
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.
8. 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 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 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.
10. ADVANTAGES OF SAVONIUS WIND
TURBINE OVER OTHER WIND TURBINES
• Savonius turbines are used whenever cost or 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. 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.
• 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.
12. DESIGN OF BLADE
In the project three blade with vertical shaft are used, it has a height &
width of 18 inches & 13 inches respectively. The angle between two blades
is 600. So if one Blade moves other blades comes in the position of first
blade, so the speed is increases.
13. 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 &
light in weight for the six blade, the shaft used is very thin in size
are all properly fitted. So no problem of slipping & fraction is
created, it is made up of hollow Aluminum which is having very
light weight. Length of shaft & diameter are 18 inches & 2.54cm
respectively. And at the top and bottom ends mild steel of length
1inch each are respectively are fixed to give strength to the hollow
shaft.
14. 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
15. AN ELECTRIC DYNAMO
For generation of electricity from the designed our vertical axis wind
turbine, we chose a Bicycle dynamo which has the capacity to light a bulb
of 12 V. This electric dynamo has the capacity.
20. 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,
K.E=½ mv2. ………………….. (1)
K.E = kinetic energy
m = mass
v = velocity,
M is equal to its Volume multiplied by its density ρ of air
M = ρ AV ………………….. (2)
Substituting eqn(2) in eqn(1)
We get,
K E = ½ ρ AV.V2
K E = ½ ρ AV3 watts
ρ = density of air (1.225 kg/m3)
A = π D2 /4 (Sq.m)
D = diameter of the blade
A = π*(1.22) 2 /4
A = 1.16Sq.m
P = 1/8 ρ π D2 V3
Available wind power Pa = (½ ρ π D2 V3)/4
21. TRAIL 1
FOR VELOCITY 4.5m/s
Pa = (½ ρ π D2 V3)/4
Pa = (½*1.225*π*1.222 *4.53)/4
Pa = 65.244watt
TRAIL 2
FOR VELOCITY 5.5m/s
Pa = (½ ρ π D2 V3)/4
Pa = (½*1.225*π*1.222 *5.53)/4
Pa = 119.12watt
TRAIL 3
FOR VELOCITY 7.5m/s
Pa = (½ ρ π D2 V3)/4
Pa = (½*1.225*π*1.222 *7.53)/4
Pa = 302.06watt
TRAIL 4
FOR VELOCITY 10m/s
Pa = (½ ρ π D2 V3)/4
Pa = (½*1.225*π*1.222 *103)/4
Pa = 716.00watt
22. ADVANTAGES
• There are several reasons why we would choose a vertical axis wind turbine
over a horizontal axis windmill.
• They are mounted lower to the ground making it easy for maintenance if
needed.
• They start creating electricity at speeds of only 6 mph. And
• Third, they may be able to be built at locations where taller structures, such as
the horizontal type, can't be.
• Higher power utilization-- 20% higher than HAWT.
• Lower noise level--only 27-37 DB, suitable for your living condition.
• Safer operation--Spin at slower speeds than horizontal turbines, decreasing
the risk of injuring birds and also decreasing noise level.
• 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.
• 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.
24. FUTURE DEVELOPMENTS
The development of effective alternators and dynamos can be
used to harness wind energy from relatively small winds. The
use of materials like Acrylic Plastic Sheets can be used to
develop low cost VWAT
25. BIBILOGRAPHY
• Eggleston, David M. Wind Turbine Engineering
Design. Van Nostrand Reinhold, 1987.
• Hunt, Daniel V. Wind power: A Handbook on Wind
Energy Conversion Systems. Van Nostrand Reinhold,
1981.
• Kovarik, Tom, Charles Pupher, and John Hurst. Wind
Energy. Domus Books, 1979.
• Park, Jack. The Wind Power Book. Cheshire Books,
1981.
• Putnam, Palmer Cosslett. Power from the Wind. Van
Nostrand Company,
