Influence of blade numbers on start-up performance of vertical axis tidal current turbines

Abstract

To alleviate the energy crisis, the tidal energy extraction has become a hot topic in recent years. As a commonly utilized energy converter, a primary concern of vertical axis tidal turbines (VATTs) is the incapability to self-start. Previous studies have found that the starting performance has a great correlation with the number of blades. However, the detailed effects of blade number on starting characteristic are not fully understood. Therefore, it is necessary to further assess the influences of the number and azimuthal angle of blades on starting characteristics. In this study, we investigate the effects of the blade number on start-up performance of VATTs by means of the commercial Computational Fluid Dynamic (CFD) software CFX. It can be seen that the increase of the blade number results in a more homogeneous flow field, and the varying angles can lead to a high average torque. Besides, the region of 100°–120° is proved that all turbines with three different blade numbers can achieve a better starting performance.