The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Template:425inprogress

  • The intent of this project, created in collaboration with Mech425, is to identify the best angle for flat, uniform blades that would typically be used to create homemade wind turbines


  • The project has been selected to provide support to individuals looking to generate electricity by harvesting the wind.


  • The target audience are people who can not afford commercially available models and have chosen to build their own.


Windmills have many functions and can be operated wherever there is access to wind. Windmills use their blades, or sails, to convert the energy in wind into rotational motion. This rotational motion can either be used for direct work or converted again into electricity. Originally, windmills were used to perform the grinding at mills. Today, they are still used for this purpose but have extended their range of uses to pumping water and primarily for electricity generation, In lesser economically developed countries, the electricity generated by homemade windmills are often used to charge batteries and cell phones or operate lighting, radios and irrigation pumps.

Modern, commercially available wind turbines are tailored to address specific wind speeds and are capable of generating megawatts of electricity from each turbine. However, homemade solutions are often low-tech and have undergone little scrutiny in terms of optimization. This report intends to identify to best angle to tilt the blades in relation to the oncoming wind and what length of blade is best suited for electricity generation.

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.
 


-- Engineering Calculations --


1. Power available to the turbine



2. Maximum Possible Efficiency


The 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.



Angle of blade and the resulting forces to spin the blades versus surface area exposed



Length = Additional rotational force Vs. torque / momentum required to spin blade



Cookies help us deliver our services. By using our services, you agree to our use of cookies.