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Energies 2010, 3(4), 634-649; https://doi.org/10.3390/en3040634
2. Development of a Collection-Acceleration Device for Wind (Diffuser Shroud Equipped with a Brim, Called “Wind-Lens”)
2.1. Selection of a Diffuser-Type Structure as the Basic Form
2.2. Idea of a Ring-Type Plate Which Forms Vortices (It is called “Brim”)
2.3. Characteristics of a Wind Turbine with Brimmed Diffuser Shroud
- Four-fivefold increase in output power compared to conventional wind turbines due to concentration of the wind energy (“wind-lens” technology).
- Brim-based yaw control: The brim at the exit of the diffuser makes wind turbines equipped with a brimmed diffuser rotate following the change in the wind direction, like a weathercock. As a result, the wind turbine automatically turns to face the wind.
- Significant reduction in wind turbine noise: Basically, an airfoil section of the turbine blade, which gives the best performance in a low-tip speed ratio range, is chosen. Since the vortices generated from the blade tips are considerably suppressed through the interference with the boundary layer within the diffuser shroud, the aerodynamic noise is reduced substantially .
- Improved safety: The wind turbine, rotating at a high speed, is shrouded by a structure and is also safe against damage from broken blades.
- As for demerits, wind load to a wind turbine and structural weight are increased.
3. Development of a Shrouded Wind Turbine with Compact Brimmed Diffuser
3.1. Experimental Method in Output Performance Test of Compact Wind-Lens Turbines
3.2. Selection of Compact Brimmed Diffuser Shape as Wind-Lens
3.3. Output Power of Wind-Lens Turbine with the Compact Diffuser Length
3.4. Field Experiment
4. Application of 5 kW Wind-Lens Turbines for Supplying Stable Electricity to an Irrigation Plant in China
5. Efficient Utilization of Wind Energy on the Seashore in an Urban City
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