Abstract
The hydrodynamic interaction between turbines in tidal arrays is strongly influenced by inter-device spacing, affecting both energy extraction and structural loading. This study numerically investigates the influence of transverse (1.5D and 2D) and longitudinal (4D and 6D) spacing on wake development, turbine performance, and blade-resolved moment loads in staggered three-turbine arrays of horizontal-axis tidal turbines. The simulations consider the full-scale SAFL RM1 turbine (rotor diameter D = 20m). Three-dimensional unsteady Reynolds-averaged Navier–Stokes simulations with fully resolved blade geometry were performed to capture wake interaction and cyclic load variation.
The results show that turbine staggering can enhance downstream turbine performance through a local duct effect between upstream devices; however, the magnitude of this enhancement depends strongly on transverse spacing. For the non-optimal 1.5D spacing, the downstream turbine exhibits only marginal performance gains (2–5%) due to interaction of the rotor with the upstream turbines wake. Increasing the transverse spacing to 2D increases downstream turbine performance by approximately 28–31% relative to the standalone case.
Blade load analysis shows that insufficient transverse spacing significantly amplifies cyclic loading, with direct implications for fatigue loading and blade life, whereas adequate spacing produces substantially reduced load variations. The results highlight the importance of transverse spacing in achieving both efficient energy extraction and improved structural reliability in staggered tidal turbine arrays.