Abstract
The vertical axis marine current turbine is emerging as a promising candidate for renewable energy applications, while its wide application is currently limited by low and unsteady power output. In this paper, the influence of helical triangle blade on the performance of vertical axis marine current turbine has been investigated. Four types of helical triangle blades with helical wrap angle of 15°, 30°, 45° and 60° at half blade height have been studied, and compared with conventional straight blades. It is found that the stability of the power output of the turbines is improved by the helical triangle blade with the increase of helical wrap angle up to 15°. The helical triangle blade with 15° helical wrap angle named as “HT blade” has the best performance. Its maximum improvement of power coefficient is 13.4% as well as improvement of the stability of power output. Furthermore, we confirmed that HT blade effectively reduced the scale of wake and stall vortex as well as the amplitude of pressure fluctuation on its surface compared to that of the original straight blade. Therefore, the properly-designed helical triangle blades are conducive to the operation stability and power output of the vertical axis tidal current turbines.