Development and analysis of vertical-axis wind turbines - Wind Power Generation and Wind Turbine Design - page 299

developed to the point where this viscous fl ow analysis tool is available to most
researchers in the academic and commercial sectors. However, application of this
tool to VAWTs is not straightforward as full transient analysis and signifi cant mesh
refi nement are necessary for meaningful results. CFD analysis of VAWTs does not
appear to have been widely reported in the literature to date, although the research
team at the École Polytechnique de Montréal have previously reported on their devel-
opment of several viscous analysis codes for VAWTs [39] and more recently articles
have appeared on CFD analysis of vertical-axis marine current turbines [33, 34].

4 Summary

This chapter has summarised the principles of operation and the historical develop-
ment of the main types of VAWT. The Darrieus turbine remains the most promis-
ing of the vertical-axis rotor types for application to the utility-scale generation of
electricity. The intense period of research, development and demonstration during
the 1970s and 1980s did not lead to the development of a technology that is able to
compete commercially with the three-bladed HAWTs that have come to dominate
the market at large scale. Nevertheless new opportunities are opening up in the
areas of marine current turbines and building-integrated wind turbines where the
VAWTs may yet be competitive. In principle, the aerodynamic analysis of VAWTs
is more complicated than that of HAWTs due to the signifi cant variation of air
velocity as a function of blade azimuth angle. The double-multiple-streamtube
analysis summarised herein provides a tool that is relatively straightforward to use
for those wishing to undertake an analysis of conventional VAWT designs.

R eferences

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