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The Ideal Efficiency of Vertical-Axis Wind Turbines

BG

Membre a labase

Barry G. Newman

Résumé du colloque

Betz used actuator-disc theory to determine the maximum power coefficient of horizontal-axis wind turbines as a function of tip-speed ratio λ. This analysis has recently been formulated for vertical-axis machines and, when compared with experiment, seems to give slightly pessimistic results. The limit for large λ is the same as the conventional Betz value, \( \frac{16}{27} \). A pair of discs in tandem is a more suitable representation of a vertical-axis wind turbine and the limit for this configuration is shown to be \( \frac{16}{25} \). For academic interest the analysis has now been extended to actuator discs giving a maximum power coefficient of \( \frac{8n(n+1)}{3n(2n+1)^2} \) and thus a value of \( \frac{2}{3} \) when n is large.

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host icon Hôte : Université Laval

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