Design and Performance Analysis of a Horizontal-axis Ducted Tidal Current Turbine

To enhance the generated power of tidal turbine in low-velocity regions, a relatively short ducted tidal current turbine is designed by the orthogonal experiment and response surface method. The effects of duct length, expansion angle, axial position, and tip clearance on the performance of the ducted turbine are analyzed by CFD (computational fluid dynamics) method. The results show that increasing the duct length and expansion angle can significantly increase the power generation. The interaction between rotor and duct is strong, and the reasonable design of axial position and tip clearance can improve the performance of ducted turbine. After optimization, the power coefficient of the ducted turbine is increased by 59.95% and the thrust coefficient is increased by 23.14%. Flow field analysis shows that the near-field wake velocity deficit of the ducted turbine is more serious. The interaction between duct shedding vortex and tip vortex reduces the stability of wake vortex belt, promotes the breaking of wake vortex, and is beneficial to wake velocity recovery. The results can provide references for the structural design and performance optimization of the ducted tidal current turbine.