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Diffuser-Augmented Wind Turbines A diffuser-augmented wind turbine (DAWT) is a wind turbine modified with a cone-shaped wind diffuser that is used to increase the efficiency of converting wind power to electrical power. The increased efficiency is possible due to the increased wind speeds the diffuser can provide. In traditional bare turbines, the rotor blades are vertically mounted at the top of a support tower or shaft. In a DAWT, the rotor blades are mounted within the diffuser, which is then placed on the top of the support tower. Additional modifications can be made to the diffuser in order to further increase efficiency. Mechanics Wind power measures how much energy is available in the wind, and it can be represented by the following equation w=(1/2)rAv^3 where r is air density, A is rotor area, and V is wind velocity.  |
Betz's Law
Betz's law indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. It was published in 1919 by the German physicist Albert Betz. The law is derived from the principles of conservation of mass and momentum of the air stream flowing through an idealized "actuator disk" that extracts energy from the wind stream. According to Betz's law, no turbine can capture more than 16/27 (59.3%) of the kinetic energy in wind. The factor 16/27 (0.593) is known as Betz's coefficient. Practical utility-scale wind turbines achieve at peak 75–80% of the Betz limit. The Betz limit is based on an open-disk actuator. If a diffuser is used to collect additional wind flow and direct it through the turbine, more energy can be extracted, but the limit still applies to the cross-section of the entire structure. Concepts Betz's law applies to all Newtonian fluids, including wind. If all of the energy coming from wind movement through a tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |