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Development and evaluation of passive variable-pitch vertical axis wind turbines

Vertical-axis wind turbines do not need to be oriented to the wind direction and offer direct rotary output to a ground-level load, making them particularly suitable for water pumping, heating, purification and aeration, as well as stand-alone electricity generation. The use of high-efficiency Darrieus turbines for such applications is virtually prohibited by their inherent inability to self-start. The provision of blade-articulation (variable-pitch blades) has been demonstrated by a number of researchers to make Darrieus turbines self-starting. One aim of this thesis is to evaluate the various concepts manifested in the numerous specific passive variable-pitch designs appearing in the literature, often without theoretical analysis. In the present work, two separate mathematical models have been produced to predict the performance of passive variable-pitch Darrieus-type turbines. A blade-element/momentum theory model has been used to investigate the relationships between the key parameter values and turbine steady-state performance. A strategy for parameter selection has been developed on the basis of these results. A free vortex wake model for passive variable-pitch turbines has been developed, allowing the study of unsteady performance. Significant reduction of average ef- ficiency in a turbulent wind is predicted for a Darrieus turbine. The improved low-speed torque of passive variable-pitch turbines is predicted to significantly improve turbulent wind performance. Two new design concepts for passive variable-pitch turbines are presented that are intended to allow greater control of blade pitch behaviour and improved turbulent wind performance. A prototype turbine featuring these design concepts has been designed, constructed and tested in the wind tunnel. As part of this testing, a technique has been developed for measuring the pitch angle response of one of the turbine blades in operation. This allows comparison of predicted and measured pitch histories and gives insight into the performance of turbines of this type. Results have demonstrated the usefulness of the mathematical models as design tools and have indicated the potential of one of the new design concepts in particular to make a vertical axis wind turbine self-starting.
Date January 2002
CreatorsPawsey, N.C.K., Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW
PublisherAwarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering
Source SetsAustraliasian Digital Theses Program
Detected LanguageEnglish
RightsCopyright N.C.K. Pawsey,

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