Mao Zhaoyong

A Numerical Study on the Improvement of the Performance of a Banki Wind Turbine

Banki wind turbine is a kind of vertical axis wind turbine (VAWT) with high solidity, and has been proved to have a relatively high starting torque and maximum power coefficient under low wind conditions. This study introduces an arc-shaped windshield to further improve the performance of Banki wind turbines. The windshield is placed in front of the turbine to deflect wind and reduce the negative torque on the blades in the upwind direction. Computational investigations are carried out to study the influence of the angle of the arc-shaped windshield on the performance of the turbine using the commercial computational fluid dynamics (CFD) code Fluent 13.0. The results demonstrated that the maximum power coefficient of the Banki wind turbine was increased by 66.9% with the optimal windshield angle of 60°. The maximum power coefficient was found to be 0.2784 at a tip speed ratio of 0.5 in the presence of the windshield.

Design of a Novel Vertical Axis Water Turbine With Retractable Arc-Type Blades

A drag-type vertical axis water turbine, like Savonius, experiences negative torque in the returning half cycle, which limits the power efficiency. A new drag-type turbine, which consists of several retractable blades that are mounted on a drum, is designed and analyzed in this paper. The open angle of each blade is controlled to achieve a high output performance. Kinematics analysis demonstrated that the returning blades can fit to the drum and negative torques can then be considerably deduced. Two-dimensional computational fluid dynamics simulations were performed to give detailed information about the output of the turbine. The simulation results show that the maximum averaged power coefficient is 0.2595, obtained at a flow coefficient of 0.4.