Development and analysis of vertical-axis wind turbines
Vertical axis turbines (VAWTs) have been demonstrated to be effective devices for extracting useful energy from the wind. VAWTs have been used to generate mechanical and electrical energy at a range of scales, from small-scale domestic applications through to large scale electricity production utilities. This chapter summarises the development of the main types of VAWT, including the SAvonius, Darrieus and Giromill designs. A summary of the multiple-streamtube analysis of VAWTs in also provided to illustrate how the complex aerodynamics of these devices may be analysed using relatively straightforward techniques. Results from a double-multiple-steamtube analysis are to illustrate the details of the performance of VAWTs in terms of turbine blade loads and rotor power output as a function of fundamental parameters such as tip speed ratio. The implications for VAWT design are discussed.