sin αst

CONCEPTUALISATION
The embodiment design phase involves further development of the principal solution of
figure 4.17 into a design proposal, which is optimised and finalised in the detail design
phase. An overall presentation of the finalised layout is given in the following chapter. A
more thorough description of key design details such as rotor, tower and generator is
given in the subsequent chapters.
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4.6 Summary
This chapter has defined basic wind turbine terms such as lift, drag and tip-speed ratio,
thus making its content more comprehensible to engineers without a background in wind
turbine technology.
A survey of numerous different wind turbines and their key properties was performed
with focus on proven HAWT and VAWT designs, including Savonius, Giromill and Darrieus
turbines.
It was found that the concepts without a proven self-starting mechanism are unfit for use
in developing countries and hence candidates in this category were eliminated. The re-
maining concepts were subjected to a systematic evaluation facilitated by a decision-
matrix. From this it was evident that the HAWT and the Savonius wind turbine are the
front-runner candidates when taking into consideration the relative evaluation criteria.
Through a technical assessment, exploring further aspects of the two best candidates, it
was concluded that the Savonius wind turbine is very impractical and difficult to handle
when it has the required structural size. The HAWT concept has therefore been adopted as
the most suitable solution for the present purpose.