sin αst

CONCEPTUALISATION
Figure 4.14: Power coefficient as a function of tip-speed ratio for several wind turbine con-
cepts [10, p. 79]
A systematic evaluation of the concepts is carried out in the following section, which is
followed by a technical assessment in section 4.4.
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4.3 Evaluation
All of the wind turbine concepts, described in the previous section, will theoretically fulfil
the demands of the requirement specification and thus provide a functioning solution for
the present purpose. Prior to assessing the quality of the concepts by evaluation it has
been decided to eliminate concepts without a proven self-starting mechanism, as lack of
such will render the solutions useless in practice. This means that the following wind tur-
bine concepts are selected for further evaluation:
� HAWT
� Cycloturbine
� Savonius
� Helical Darrieus
The selected wind turbine concepts are evaluated with reference to the wishes of the re-
quirement specification, table 2.1. The evaluation criteria are compiled in a decision-
matrix that enables a comparative and multi-dimensional analysis of the wind turbine