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Optimized Blade Design for Homemade Windmills

1,235 bytes added, 23:17, 3 April 2010
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[http://www.ted.com/talks/lang/eng/william_kamkwamba_how_i_harnessed_the_wind.html William Kamkwamba] is a fantastic example of who could benefit from the analysis presented in this report. His ambition for a better life and access to scrap materials was transformed into a working device that provides both light and irrigation to his community and inspiration to the rest of the world. As more people begin to develop solutions for their own energy needs, there is great value in optimizing these devices to maximize their social benefit.<br>&nbsp;
 
 
-- Engineering Calculations --
 
 
 
1. Power available to the turbine
 
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2. Maximum Possible Efficiency
 
 
The [http://en.wikipedia.org/wiki/Betz'_law#Three_independent_discoveries_of_the_turbine_efficiency_limit, Betz limit] was developed by Albert Betz and seeks to determine the maximum possible energy that can be derived by a device from a stream of fluid, flowing at a given speed. In the case of windmill, the maximum theoretical efficiency of a thin rotor can be found based on the following assumptions:
 
 
* The rotor is considered ideal, having an infinite number of blades and no drag.
 
 
* The flow into and out of the rotor is axial and in accordance conservation equations.
 
 
* The fluid is modeled based on incompressible flow.
 
 
 
The Betz limit has been able to predicted the maximum value for the power coefficient to be 0.593. This means that the theoretical limit of power removed from from the fluid is 59.3%, although current commercial wind turbines are able to achieve 40 - 50% conversion efficiency.
 
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Angle of blade and the resulting forces to spin the blades versus surface area exposed
 
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Length = Additional rotational force Vs. torque / momentum required to spin blade
 
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