Savonius Wind Turbine
These plans are for the construction of a machine called a Savonius wind turbine. Wind turbines come in two general types, those whose main turning shaft is horizontal and points into the wind, and those with a vertical shaft that points up. The Savonius is an example of the vertical axis type. It consists of two simple scoops that catch the wind and cause the shaft to turn.
This type of turbine is simple to build, but is not nearly as efficient as a well-designed horizontal axis turbine. The Savonius turbine relies solely on drag to produce the force that turns their shaft. One side of the turbine catches the moving air more than the other, causing the turbine to spin. This design does not allow the turbine to spin faster than the oncoming wind, which makes them a poor choice in areas where winds are light.
|
Horizontal axis turbines are by far the most common kind of wind turbine. They can be seen at several places across Canada and the United States. They are also becoming common in Europe and many other countries around the world. These turbines feature wing-like blades that generate aerodynamic lift as the wind blows past them, causing the central shaft to turn. To operate at peak efficiency, this type of turbine must always face directly into the wind. Many horizontal turbines have a large wind vane that acts like a sail, helping them to stay pointed in the right direction.
Making electricity
A horizontal axis turbine.
We are surrounded by hundreds of appliances that use electricity to do work. But what is electricity? Basically, electricity is a flow of electrons in a metal wire, or some other conductor. Electrons are tiny particles found inside atoms, one of the basic building blocks of all matter. We call the flow of electrons through any conductor a "current of electricity."
Each electron carries a tiny negative charge. When they move through a conductor, they produce an invisible field of magnetic force, similar to that found around a magnet. The strength of that field depends on how many electrons are in motion. You can concentrate this field by winding the wire in which the electrons move into a tight coil with many turns. This causes many more electrons to be in motion in a small space, resulting in a stronger field. If you then place a piece of iron in the middle of the coil, the electromagnetic field will turn the iron into a powerful magnet.
While it is true that electrons moving through a conductor produce a magnetic field, the reverse is also true. You can make electrons move in a wire by "pushing" them with a moving magnet. This is in fact how an electrical generator works. Electrical generators usually contain powerful magnets that rotate very close to dense coils of insulated wire. The coils develop a flow of electrons that becomes an electrical current when the generator is connected to an electric circuit.
You will be building an electrical generator as part of this project. It uses moving magnets to create a current of electricity in coils of wire. This generator is technically called an alternator because the electrons move back and forth in the wire, rather than flowing in just one direction as they do from a battery. A meter connected to the wire would show that the charge of the wire switches or alternates between positive and negative as the electrons change directions. Such an electrical current is called alternating current or AC. Household electrical current is alternating current. Appliances have to be specially designed to use it. The other type of current is called direct current, because the electrons move in one direction only. Most battery-powered appliances such as calculators and portable CD players use direct current.
Safety Precautions
- Utility knives and scissors can be dangerous! Use caution when cutting materials using them. The blades of most utility knives can be extended and locked in place. Extend the blades only far enough to cut all the way through the material, no farther. Be sure they are locked in position while cutting.
- For a safe and easy cutting make sure the blades of your utility knives are always sharp (ask your teacher for assistance in breaking off dull blades)
- Hot glue guns can cause serious burns, as can the glue if it comes in contact with your skin.
- The magnets you will be using can cause serious damage to computers or other electronic devices. Be sure to keep them away from credit cards, computer disks, audio tapes, or any other materials on which information is stored magnetically.
Build It!
(Click to continue to the construction plans)
- Set the selector on the digital volt meter to read Volts AC. At this setting, the meter will detect the number of volts of alternating current your turbine produces. The Pembina Institute
- Attach the test clips on the volt meter to the wire leads on your turbine.
- Blow on your turbine to cause it to spin. Have a partner watch the readings on the display of the meter. Record your results. A well-assembled wind turbine should be able to produce between 1 and two volts by blowing on it. A more consistent way to test your turbine is to use a stream of air from an appliance such as a blow dryer (set for COOL) or a vacuum cleaner with the hose plugged into the discharge end. Measure the voltage of your turbine and compare with others.
- You may make small modifications to improve the efficiency of your turbine. Look for sources of friction that might slow down its rotation, or find ways to bring the coils closer to the spinning magnets.
