The design and testing of a vertical-axis wind turbine using sails

Abstract

A vertical-axis wind turbine using sails rather than solid blades has been designed and tested at large model scale in a 15 ft diameter wind tunnel. The turbine has a relatively high solidity, three blades and an operating range of tip speed ratios from zero to about 2.5. Two types of sail have been tested—a double sail consisting of two layers of cloth wrapped round a circular leading edge dowel, and a jib sail consisting of a single layer of cloth with the leading edge held by a taut wire. The measured power outputs are about half those of a turbine with solid aerofoil blades running at tip speed ratios of 5 or 6. However, the cost and skill required for manufacture of the sail turbines are less and it is concluded that the present designs, which can be self starting if the trailing edge tension is appropriately set, may have application for 1 kW machines in developing countries.