Small Vertical Axis Wind Turbines: aerodynamics and starting behavior

In urban areas the wind is very turbulent and unstable with fast changes in direction and velocity. In these environments, the use of small vertical axis wind turbines (VAWT) becomes increasingly attractive due to several advantages over horizontal axis wind turbines (HAWT). However, such designs have received much less attention than the more common propeller-type designs and the understanding of same aspects of their operation remains, to this day, incomplete. This is particularly true of their starting characteristics. Indeed, same authors heuristically maintain that they cannot start without external assistance. This paper reviews the cause of the inability of the low solidity fixed pitch vertical axis wind turbines to self-start, and investigates the way of overcoming this draw back.