Abstract
To design a high-efficiency bidirectional horizontal-axis tidal turbine (HATT) capable of adapting to tidal current energy's reciprocating characteristics, the designed S-type reversible airfoil is optimized. This study integrates class-shape transformation parameterization, computational fluid dynamics (CFD) method, and multi-island genetic algorithm to establish an optimization method for S-type reversible airfoil with the objective of maximizing lift-to-drag ratio and lift coefficient. Subsequently, the blade chord length and pitch angle distributions are obtained by designing a bidirectional HATT based on the Wilson design method. Finally, the hydrodynamic performance of the bidirectional HATT is analyzed based on the CFD method. Results demonstrate that the proposed optimization method significantly improves the lift-to-drag ratio of the S-type reversible airfoil, which is close to 40 at Reynolds number 7.3E05, and the lift-to-drag ratio increases gradually with the Reynolds number. The power coefficient of the bidirectional HATT based on the optimized S-type reversible airfoil is significantly improved, approaching 45% at a flow velocity of 2 m/s. Meanwhile, the thrust coefficient significantly decreases and then gradually decreases after the tip speed ratio reaches 6. Therefore, the bidirectional blade designed in this paper effectively improves the high efficiency and safety of bidirectional HATT, showing great potential for engineering applications.