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Wind Turbine Blades
Wind turbine blades can be made from wood, metal or fiberglass. Some home turbine blades are also cut from pieces of PVC pipe. Fiberglass is used for most of the giant commercial wind turbines in production today because it is light, very long lasting and not subject to stress fatigue. For DIY turbines, the size of the machine will determine the best material to use for the blades.
Some wind turbines have 1 or 2 blades, but most small home wind turbines have 3 or more blades. The configuration higher number of blades 3 blade configuration is more efficient because it can spin the rotor at higher speeds in lower wind. Three blade designs are also easier to balance. They are usually quieter than 1 and 2 blade designs too.
Design theory is mainly the same for all horizontal axis wind turbine blades. Wind turbine blades are generally airfoil shaped, like the wings on an airplane to create lift and help maximize efficiency. The blades usually have a twist to their shape, necessary because the blades move faster at the outer ends and slower at the bottom, toward the hub. This twist optimizes angle of attack along the blade. Similarly, the blades are tapered for improved aerodynamic performance.
Some wind turbines have 1 or 2 blades, but most small home wind turbines have 3 or more blades. The configuration higher number of blades 3 blade configuration is more efficient because it can spin the rotor at higher speeds in lower wind. Three blade designs are also easier to balance. They are usually quieter than 1 and 2 blade designs too.
Design theory is mainly the same for all horizontal axis wind turbine blades. Wind turbine blades are generally airfoil shaped, like the wings on an airplane to create lift and help maximize efficiency. The blades usually have a twist to their shape, necessary because the blades move faster at the outer ends and slower at the bottom, toward the hub. This twist optimizes angle of attack along the blade. Similarly, the blades are tapered for improved aerodynamic performance.
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For all these reasons, it is a very good idea to get a set of plans for the entire machine where the blade specifications are consistent with the other parts. Most of the online guides do a good job of sizing wind turbine blades along with the entire system. Of all the guides I've worked with or reviewed, this one is by far the best one out there.
Wind Turbine Blade Resources
Although wind turbine blade design is fairly consistent from one turbine to the next, several dimensional factors must be tailored to the overall machine design and location. The speed and torque at which a wind turbine rotates must be controlled to optimize aerodynamic efficiency in light winds.
The rotor can only spin so fast before it reaches the generator's maximum for power output and then it must be slowed. Therefore, the generator must be kept within its speed and torque limits and be prevented from spinning faster than its maximum capacity. Blade size, weight and diameter all play a part. If the blades are too big - or too small - for the generator the turbine won’t work properly, if at all. Likewise, if the tail assembly isn’t the correct size and weight, the turbine won’t turn into the wind, or furl to a slower speed when it is supposed to.
The rotor can only spin so fast before it reaches the generator's maximum for power output and then it must be slowed. Therefore, the generator must be kept within its speed and torque limits and be prevented from spinning faster than its maximum capacity. Blade size, weight and diameter all play a part. If the blades are too big - or too small - for the generator the turbine won’t work properly, if at all. Likewise, if the tail assembly isn’t the correct size and weight, the turbine won’t turn into the wind, or furl to a slower speed when it is supposed to.