FLOATING WIND TURBINES
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Joined: Sep 2010
16-10-2010, 05:36 PM
Mr. Thomas Abraham
Mr. K.R Arjun
Delano Mathew Felix
FLOATING WIND TURBINES.ppt (Size: 3.16 MB / Downloads: 691)
Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable.
Climate change concerns, high oil prices, and increasing government support, accelerates the growth of this sector.
In 2008, about 19% of global final energy consumption came from renewable sources.
With nations pledging to reduce the carbon emission to counter global warming, the need for systems that generate renewable energy has been
on a rise.
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Joined: Feb 2012
08-03-2012, 03:21 PM
FLOATING WIND TURBINES
Floating Wind Turbines.pdf (Size: 1.87 MB / Downloads: 247)
Non-renewable resources such as coal, natural gas, oil, and nuclear power are the primary
sources of energy for many parts of the world. Burning fossil fuels, however, is harmful
to the environment and fossil fuel supplies are limited and subject to price volatility. And
the safe storage and disposal of radioactive waste, the potential for radioactive
contamination from accidents or damage and the threat of nuclear explosion are serious
challenges to the success of nuclear power. Renewable resources such as wind possess
great potential because they are indigenous, non-polluting, and inexhaustible. The vision
for large-scale offshore floating wind turbines was introduced by Professor William E.
Heronemus at the University of Massachusetts in 1972 .
2 OFFSHORE WINDS, WAVES AND RESOURCES
2.1 Offshore wind speeds
Offshore wind speeds are higher than coastal wind speeds at sea level. Ten kilometres
from the shore, speeds may be 25% higher than at the coast and there are large areas of
the North Sea and Baltic with wind speeds above 8 m/s (at 50m). Offshore winds are less
turbulent than onshore winds, and wind shear is less. As the roughness of the sea
increases with wind speed (as wave heights increase), so shear and turbulence slowly rise
with wind speed above about 10 m/s.
2.2 Offshore wind farms vs. onshore wind farms
Compared with onshore wind farms, offshore wind farms have several advantages. First
of all, due to the larger wind speeds at sea, offshore wind farms may yield up to 50%
more annual electricity than onshore wind farms of equal capacity and type. Second,
onshore wind farms often meet public resistance from visual impact, noise production and
shadow casting; for offshore locations, with sufficient distance to shore, these issues are
far less important. Third, for some countries, the available technical potential is very large
compared with other renewable electricity options.
3.1 Wind power
Wind power is defined as energy derived from the conversion of kinetic energy of
moving air into useful forms such as electric energy for powering homes and industries.
Wind energy is not only a renewable form of energy, but also a clean energy source, since
it does not produce any harmful by-products or emissions that can damage the
environment. Wind energy is also an attractive form of energy generation, because it
utilizes wind which is found abundantly in many areas of the world.
3.2 Offshore wind power
Offshore wind power utilizes the vast wind energy resources found offshore to produce
electricity. More accurate wind data collection shows that most of the wind resources lie
off the coast, and this is evident in the US wind map in section 1 of this report . It is
this abundance of wind resources offshore that has brought an increased interest in the
development of electricity-generating wind facilities in open sea waters.
Joined: Apr 2012
28-07-2012, 11:22 AM
THE WIND TURBINE
BonusTurbine.pdf (Size: 677.99 KB / Downloads: 34)
THE AERODYNAMICS OF
THE WIND TURBINE
important and most visible part of the
wind turbine. It is through the rotor
that the energy of the wind is transformed
into mechanical energy that turns
the main shaft of the wind turbine.
We will start by describing why the
blades are shaped the way that they are
and what really happens, when the
Aerodynamics is the science and study
of the physical laws of the behavior of
objects in an air flow and the forces that
are produced by air flows.
The front and rear sides of a wind
turbine rotor blade have a shape roughly
similar to that of a long rectangle,
with the edges bounded by the leading
edge, the trailing edge, the blade tip and
the blade root. The blade root is bolted to
The radius of the blade is the distance
from the rotor shaft to the outer edge of
the blade tip. Some wind turbine blades
have moveable blade tips as air brakes,
and one can often see the distinct line
separating the blade tip component from
the blade itself.
If a blade were sawn in half, one
would see that the cross section has a
streamlined asymmetrical shape, with the
flattest side facing the oncoming air flow
or wind. This shape is called the bladeÕs
THE AERODYNAMIC PROFILE
The shape of the aerodynamic profile is
decisive for blade performance. Even
minor alterations in the shape of the
profile can greatly alter the power curve
and noise level. Therefore a blade designer
does not merely sit down and outline
the shape when designing a new blade.
The shape must be chosen with great care
on the basis of past experience. For this
reason blade profiles were previously
chosen from a widely used catalogue of
airfoil profiles developed in wind tunnel
research by NACA (The United States
National Advisory Committee for Aeronautics)
around the time of the Second
BEHAVE IN THE SAME WAY
Returning to the wind turbine blade, just
as in the situation for the cyclist, we can
observe the aerodynamic and force
diagrams in two different situations,
when the wind turbine is stationary and
when it is running at a normal operational
speed. We will use as an example the
cross section near the blade tip of a
Bonus 450 kW Mk III operating in a
wind speed ÒvÒ of 10 m/s.
WHAT HAPPENS WHEN
THE WIND SPEED CHANGES?
The description so far was made with
reference to a couple of examples where
wind speed was at a constant 10 m/s.
We will now examine what happens
during alterations in the wind speed.
In order to understand blade behavior
at different wind speeds, it is necessary
to understand a little about how lift and
drag change with a different angle of
attack. This is the angle between the
resulting wind ÒwÓ and the profile chord.
In the drawing below the angle of
attack is called ÒaÓ and the setting
angle is called ÒbÓ.
The setting angle has a fixed value at
any one given place on the blade,
but the angle of attack will grow as the
wind speed increases.