Vertical axis wind turbine

Mechar: Since you are going to present a paper, you should know about the topic. If you have any specific doubts, feel free to ask them here.

can you narrow down your question or help needed?

Why are you mad/angry, that you have to give a presentation?

what is the the main advantage of vertical axis wind turbine over other type of wind turbine??????????

Hi,

vertical axis windmill provide power at the base, needs no direction control ( wind direction doesn't matter). can be designed as a power generating turbine as well as high solidity (used to derive mechanical power) turbine.

mechar

what is the the main advantage of vertical axis wind turbine over other type of wind turbine??????????

Hey mechar you are going to present a paper on vertical axis wind turbine
and how can you ask a question like this "difeerence between verticle axis and other type of wind turbine?"
you can easily find it on internet I thik you are not clear with your topic!!!

Wind Turbines: Horizontal or Vertical Axis Machines?
Horizontal Axis Wind Turbines
Most of the technology described on these pages is related to horizontal axis wind turbines (HAWTs, as some people like to call them).
The reason is simple: All grid-connected commercial wind turbines today are built with a propeller-type rotor on a horizontal axis (i.e. a horizontal main shaft).
The purpose of the rotor, of course, is to convert the linear motion of the wind into rotational energy that can be used to drive a generator. The same basic principle is used in a modern water turbine, where the flow of water is parallel to the rotational axis of the turbine blades.
Vertical Axis Wind Turbines
Eole C, a 4200 kW Vertical axis Darrieus wind turbine with 100 m rotor diameter at Cap Chat, Québec, Canada. The machine (which is the world's largest wind turbine) is no longer operational. Photograph Soren Krohn
© 1997 DWIA
As you will probably recall, classical water wheels let the water arrive at a right angle (perpendicular) to the rotational axis (shaft) of the water wheel.
Vertical axis wind turbines (VAWTs as some people call them) are a bit like water wheels in that sense. (Some vertical axis turbine types could actually work with a horizontal axis as well, but they would hardly be able to beat the efficiency of a propeller-type turbine).
The only vertical axis turbine which has ever been manufactured commercially at any volume is the Darrieus machine, named after the French engineer Georges Darrieus who patented the design in 1931. (It was manufactured by the U.S. company FloWind which went bankrupt in 1997). The Darrieus machine is characterised by its C-shaped rotor blades which make it look a bit like an eggbeater. It is normally built with two or three blades.
The basic theoretical advantages of a vertical axis machine are:
1) You may place the generator, gearbox etc. on the ground, and you may not need a tower for the machine.
2) You do not need a yaw mechanism to turn the rotor against the wind.
The basic disadvantages are:
1) Wind speeds are very low close to ground level, so although you may save a tower, your wind speeds will be very low on the lower part of your rotor.
2) The overall efficiency of the vertical axis machines is not impressive.
3) The machine is not self-starting (e.g. a Darrieus machine will need a "push" before it starts. This is only a minor inconvenience for a grid connected turbine, however, since you may use the generator as a motor drawing current from the grid to to start the machine).
4) The machine may need guy wires to hold it up, but guy wires are impractical in heavily farmed areas.
5) Replacing the main bearing for the rotor necessitates removing the rotor on both a horizontal and a vertical axis machine. In the case of the latter, it means tearing the whole machine down. (That is why EOLE 4 in the picture is standing idle).

It is true VAWT are not popular commercial models unlike the horizontal axis turbines. In terms of energy conversion propeller type HAWTs are better than VAWTs due to high tip speed ratio (TSR). Wel,l darrieus has reasonably good TSR and efficiency, but the effect of centrifugal force is very high on the blades as you must be knowing.

BUT VAWTs are simple to build and in urban environment they may become popular. Well lesser theoretical efficiency dosen't have any effect on operating cost!

They are easier to build. May be you can try one. I am suresmall urban models have a good market potential. Any comments?

Vertical Axis Wind Turbines
Eole C, a 4200 kW Vertical axis Darrieus wind turbine with 100 m rotor diameter at Cap Chat, Québec, Canada. The machine (which is the world's largest wind turbine) is no longer operational. Photograph Soren Krohn
© 1997 DWIA
As you will probably recall, classical water wheels let the water arrive at a right angle (perpendicular) to the rotational axis (shaft) of the water wheel.
Vertical axis wind turbines (VAWTs as some people call them) are a bit like water wheels in that sense. (Some vertical axis turbine types could actually work with a horizontal axis as well, but they would hardly be able to beat the efficiency of a propeller-type turbine).
The only vertical axis turbine which has ever been manufactured commercially at any volume is the Darrieus machine, named after the French engineer Georges Darrieus who patented the design in 1931. (It was manufactured by the U.S. company FloWind which went bankrupt in 1997). The Darrieus machine is characterised by its C-shaped rotor blades which make it look a bit like an eggbeater. It is normally built with two or three blades.
The basic theoretical advantages of a vertical axis machine are:
1) You may place the generator, gearbox etc. on the ground, and you may not need a tower for the machine.
2) You do not need a yaw mechanism to turn the rotor against the wind.
The basic disadvantages are:
1) Wind speeds are very low close to ground level, so although you may save a tower, your wind speeds will be very low on the lower part of your rotor.
2) The overall efficiency of the vertical axis machines is not impressive.
3) The machine is not self-starting (e.g. a Darrieus machine will need a "push" before it starts. This is only a minor inconvenience for a grid connected turbine, however, since you may use the generator as a motor drawing current from the grid to to start the machine).
4) The machine may need guy wires to hold it up, but guy wires are impractical in heavily farmed areas.
5) Replacing the main bearing for the rotor necessitates removing the rotor on both a horizontal and a vertical axis machine. In the case of the latter, it means tearing the whole machine down. (That is why EOLE 4 in the picture is standing idle).