A Study Made By three Mechanical Engineering Students In the Lebanese University Faculty Of Engineering ROOMIEH About the Wind Trubines

1. WIND TURBINES
STUDY ABOUT RESIDENTIAL WIND TURBINES
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2. Prepared by 4th year Mechanical Engineering Students
Lebanese University Faculty of Engineering Roomieh
EliaTohme
WadihKhater Jamil Chibany
INSTRUCTOR
Elias Kinnab, PhD
Professor
Professor Department of Mechanical Engineering
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3. Definition:
A wind turbine is a machine for converting the kinetic
energy in wind into mechanical energy.
Types of wind turbines:
Windmills: Vertical Axis Wind Turbine Horizontal Axis Wind Turbine
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4. VERTICAL WIND TURBINES
SAVONIUS WIND TURBINE
It is useful for grinding grain,
pumping water, and many other
tasks, but its slow rotational
speeds make it unsuitable for
generating electricity on a large-scale.
FLAPPING PANEL WIND
TURBINE
This illustration shows the wind
coming from one direction, but
the wind can actually come from
any direction and the wind turbine
will work the same way.
DARRIEUS WIND
TURBINE
It is characterized by its C-shaped
rotor blades which give it its
eggbeater appearance. It is
normally built with two or three
blades.
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5. HORIZONTAL AXIS WIND TURBINES
UP-WIND TURBINES
Some wind turbines are designed
to operate in an upwind mode
(with the blades upwind of the
tower). Smaller wind turbines use
a tail vane to keep the blades
facing into the wind.
DOWN-WIND TURBINES
Other wind turbines operate in a
downwind mode so that the wind
passes the tower before striking
the blades. Without a tail vane, the
machine rotor naturally tracks the
wind in a downwind mode.
SHROUDED WIND
TURBINES
Some turbines have an added
structural design feature called an
augmenter. The augmenter is
intended to increase the amount
of wind passing through the
blades.
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6. CHARACTERISTICS
Cut-in Speed
Rated Speed
Cut-out Speed
Turbine size
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7. Betz’s Law
According to Betz's law, no turbine can capture more than
16/27 (59.3%) of the kinetic energy in wind
η =
power
1
2 ρAtUu
3
=
1
2
1 −
Ud
Uu
1 +
Ud
Uu
2
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8. EQUATIONS
Available Wind Power:
3
1
P A V a T  
2
Wind Turbine Power and Efficiency
3
1
2
P
T
A V
C
a T
p


Wind Turbine Torque
1

F A V a T 
2
2
1
T A V a T  
2
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9. Rotor Torque
Rotor Tip Relative Speed
NR
V
1

R
V
Vrw
T
r
 2
 
R
P 
 
V
V
C
C
rw
T
A V T
C
a T
T
2
2

ρ = Density of air = 1.2 kg/m3 (.0745 lb/ft3), at sea level, 20 oC and dry air
A = swept area = (radius)2, m2
V = Wind Velocity, m/sec.
ρ = 1.16 kg/m3, at 1000 feet elevation
ρ = 1.00 kg/m3, at 5000 feet elevation 9

10. 10

11. ENERGY CONVERSION
Wind energy is created when the atmosphere is heated
unevenly by the Sun, some patches of air become warmer
than others. These warm patches of air rise, other air
rushes in to replace them – thus, wind blows.
A wind turbine extracts energy from moving air by slowing
the wind down, and transferring this energy into a
spinning shaft, which usually turns a generator to produce
electricity. The power in the wind that’s available for
harvest depends on both the wind speed and the area
that’s swept by the turbine blades.
Hot air goes up
and creates low
pressure region
Cooler air moves
from high pressure
region
• the wind is used to generate mechanical energy or
electrical energy.
• Wind turbines converts the kinetic energy of the wind
into mechanical energy first and then into electricity if
needed.
• The energy in the wind turns propeller like blades
around a rotor shaft.
• It is the design of the blades that is primarily responsible
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for converting the kinetic energy into mechanical energy.
• The rate of change of angular momentum of air at inlet
and outlet of a blade gives rise to the mechanical torque.

12. Power Generated by Wind Turbine
Wind turbines with rotors (turbine blades and hub) that
are about 8 feet in diameter (50 square feet of swept
area) may peak at about 1,000 watts (1 kilowatt; kW),
and generate about 75 kilowatt-hours (kWh) per month
with a 10 mph average wind speed.
Homes typically use 500-1,500 kilowatt-hours of electricity
per month. Depending upon the average wind speed in
the area this will require a wind turbine rated in the range
5-15 kilowatts, which translates into a rotor diameter of
14 to 26 feet.
Doubling the tower height increases the expected wind
speeds by 10% and the expected power by 34%.
doubling the altitude may increase wind speed by 20% to
60%.
Tower heights approximately two to three times
the blade length have been found to balance material
costs of the tower against better utilization of the more
expensive active components.
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13. THE INSIDE OF A WIND TURBINE:
Nacelle
Anemometer Blades
Wind vane Yaw drive
Brake Controller
Tower Wind direction
Gear box
Generator High-speed shaft
Low-speed shaft
Pitch Rotor
Yaw motor 13

14. RESIDENTIAL WIND TURBINE
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15. BLADES DESIGN: NUMBER OF BLADES
NUMBER OF BLADES :
ONE
Blades easier to install because entire
rotor can be assembled on ground.
Captures 10% less energy than two blade
design.
Ultimately provide no cost savings.
Higher speed means more noise, visual, and
wildlife impacts.
NUMBER OF BLADES :
TWO
Advantages & disadvantages similar
to one blade.
Need teetering hub and or shock
absorbers because of gyroscopic
imbalances.
Capture 5% less energy than three
blade designs.
NUMBER OF BLADES :
THREE
Balance of gyroscopic forces.
Slower rotation.
Increases gearbox &
transmission costs.
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More aesthetic, less noise, fewer
bird strikes.

16. BLADES DESIGN: BLADE COMPOSITION
WOOD
Strong, light weight, cheap,
abundant, flexible.
Solid plank.
Laminates.
Veneers.
Composites.
METAL
Steel: Heavy & expensive.
Aluminum: Lighter-weight and
easy to work with.
Expensive.
Subject to metal fatigue.
FIBERGLASS
Lightweight, strong, inexpensive, good fatigue
characteristics
Variety of manufacturing processes:
Cloth over frame.
Pultrusion .
Filament winding to produce spars.
Most modern large turbines use fiberglass.
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17. Lift/Drag Forces Experienced by Turbine Blades
Airfoil Shape
Twist & Taper
Fastest
Faster
Fast
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18. Tip-Speed Ratio
There is an optimum angle of attack which creates the
highest lift to drag ratio.
Because angle of attack is dependent on wind speed,
there is an optimum tip-speed ratio
TSR=Ω푅/푉
Performance over Range of Tip Speed Ratios
• Power Coefficient Varies with Tip Speed Ratio.
• Characterized by Cp vs Tip Speed Ratio Curve.
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19. Rotor Solidity
 Solidity is the ratio of total rotor platform area to total
swept area.
1-Low solidity (0.10) = high speed, low torque 2-High solidity (>0.80) = low speed, high torque
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20. Location for a small or micro-scale wind turbine
Many residential areas are not suitable for wind turbines
as buildings and trees shade the wind and create
turbulence which can reduce the efficiency and lifespan of
a turbine considerably. Generally speaking, the ideal
location is on top of a high mast on a south westerly
facing hill with gently sloping sides surrounded by clear
countryside which is free from obstructions such as trees,
houses or other buildings. Here the wind flows relatively
smoothly and steadily enabling it to drive wind turbines
with greater efficiency.
Ideally, the turbine should be 10m above any obstacle
within 100m. As a rule of thumb, a wind generator should
be installed no closer to an obstacle than at least ten
times the object's height, and on the downwind side. The
preferred distance is twenty times the height of the
object.
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21. Calculation of the energy produced over a year:
Here is a chart that estimates annual energy production
for different sized turbines in different annual mean wind
speeds.
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22. The figure below shows the data from which the power curve (the green line) was obtained as
an average of the binned power and wind speed readings. The peak power is obviously
electronically regulated so that there is a sharp cut-off at 5.2 kilowatts.
The table below shows the equivalent annual energy production in kilowatt-hours obtained by
multiplying the mean power results by 8,760 - the number of hours in a year.
Annual energy production in kilowatt-hours
Mean wind speed (m/s) = 5 6 7 8 9 10
Power calculation 8,669 13,101 17,378 21,222 24,544 27,341
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23. Economical Approach:
Leading Manufacturers of Wind Turbine:
1. Vestas (Denmark) - 35,000 MW
2. Enercon (Germany) - 19,000 MW
3. Gamesa (Spain) – 16,000 MW
4. General Electric (USA, Germany) – 15,000 MW
5. Siemens (Denmark, Germany) – 8,800 MW
6. Suzlon (India) – 6,000 MW
7. Nordex (Germany) – 5,400 MW
8. Acciona (spain) – 4,300 MW
9. Repower (Germany) – 3,000 MW
10. Goldwind (china) – 2,889
1.0 – 2.5 million per MW for large scale
- Most commercial wind turbine are in the range of 2 MW
$3,000 – 5000 per kW in range less than 10kW
- $15,000 - $25,000 for residential home application
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24. References:
American Wind Energy Association (AWEA). 2013a. AWEA U.S.
Wind Industry Annual Market Report: Year Ending 2012.
Washington, D.C.: American Wind Energy Association.
Anderson, D. A., Tannehill, J. C., Pletcher, R. H., 1984:
Computational Fluid Mechanics and Heat Transfer. New York:
Hemisphere Publishing Corporation, pp. 599.
Wind Turbines Theory - The Betz, Equation and Optimal Rotor Tip
Speed Ratio, Magdi Ragheb1 and Adam M. Ragheb2,
1Department of Nuclear, Plasma and Radiological Engineering,
2Department of Aerospace Engineering
en.wikipedia.org
IEEE PES Wind Plant Collector System Design Working Group
National Energy Education Development Project (public domain)
University of Tennessee, October 28, 2009 at 11:26 from IEEE
Xplore
University of Illinois at Urbana-Champaign, 216 Talbot Laboratory,
USA
www.telosnet.com
www.whirlopedia.com
www.windenergy.gov
Xcel Energy and EnerNex Corp. 2011. Public Service
Company of Colorado 2 GW and 3 GW Wind Integration
Cost Study. Denver, Colorado: Xcel Energy.
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25. THANKS FOR YOUR
ATTENTION
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