Development of a cyclic pitch turbine

A novel wind turbine design is proposed that increases turbine efficiency. The design consists of blades symmetrically positioned around a vertical axis. The blades experience cyclic pitch variations while rotating about the axis. The pitch variation is accomplished by an innovative mechanism that rotates the blades about a horizontal axis during rotation of the turbine. This controlled pitch variation allows the blades travelling upstream to be oriented horizontally so minimum drag is obtained. On the other hand, the blades travelling downstream are oriented vertically so maximum drag is achieved. Since the aiding downstream drag is maximum and the adverse upstream drag is minimum, this configuration allows for higher power output compared to conventional vertical axis wind turbines. Experiments on the turbine conducted in a water tunnel suggest an increase in power efficiencies.