In years past, the designs were often used to pump water. Before rural areas had plant-provided electricity, farmers used the same design to light their homes and operate essential farm equipment. The designs have become popular once again for several reasons.
Basically, all turbines can be strategically positioned in order to allow the prevailing winds to turn the blades.
As the blades or rotors turn, gears inside of a gearbox turn along with them. It is the gears that actually generate the electricity.
Aerodynamic modeling is used to determine the optimal height for the tower. The tower is typically the most expensive part of the whole system. It must be sturdy enough to withstand the pressure of the prevailing winds and strong enough to hold up the rotors.
DIY Wind Turbine Blade Basics
The number of blades is a variable. Typically, three or four blades are included in the design. But, a DIY wind turbine could have five or more.
The shape of the blades is another consideration. Straight or curved blades may be used to capture the most kinetic energy. In modern wind-farms, three curved blades are typically included in the design.
The length of the blade is another variable. In professional models, the blades range in length from 20-40 meters. In a few cases, they are even longer. The longer blades can capture more energy, but they require a taller and stronger tower.
HAWT Design & DIY Wind Turbine Considerations
A DIY wind turbine is usually modeled after the HAWT design. The turbines rotate on a horizontal, rather than a vertical axis. The main rotor shaft and electrical generator are located at the top of the tower and are pointed into the wind. A kind of weather vane is used to point the apparatus in the right direction.
A material called aero-elastic is used in the smallest turbines. The blades of large turbines are rigid in order to prevent them from being bent by strong winds and driving into the tower. They are typically made of steel or another strong metal.
The aero-elastic blades are lighter weight and flexible. If they hit the supporting pole, they do not cause damage. The towers for the lighter blades cost less to build and install.
If you want to build your own wind turbine, you might want to start with one of the smaller models. Some great things come in small packages.
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