Design of wind turbines with shroud and lobed ejectors for efficient utilization of low-grade wind energy

A one stage horizontal axis wind turbine with a shroud and lobed ejector was designed for the efficient utilization of low-grade wind energy by taking into consideration the effect of the shroud and lobed ejector. The performance of the proposed wind turbine was evaluated using the commercial software CFX. Simulation results indicated that the wind energy utilization efficiency of the proposed wind turbine increased to 66-73% at a low wind speeds ranging from 2 to 6 m/s. It was found that the complex vortices in the flow field outside the wind turbine included stream-wise vortices, normal vortices behind the lobes, and three large scale vortex rings. The shroud and lobed ejector structure in the back of the proposed wind turbine produced such an effect that the pressure at the wind turbine exit was reduced so that the turbine power output was increased by 240%. It is therefore concluded that the proposed wind turbine can be used for efficient utilization of low-grade wind energy.