Abstract
Flow perturbations carried in the wake of an upstream turbine can have a significant impact on the downstream one. To get a better understanding of the effect of unsteady asymmetric flow on a downstream turbine, fully transient simulations designed to study the effect of the wake of an upstream turbine on a downstream one were performed with a RANS k-ω SST turbulence model using ANSYS-CFX. Three different configurations were considered: the downstream turbine aligned with the upstream one, offset by 0.5D, and offset by 1D. A 10D clearance between both turbines was used. A horizontal axis tidal turbine (HATT) was used for the study. Results show that when fully in-line, the downstream turbine sees reduction in power coefficient by more than 69%, and temporal variation of this coefficient having a relative amplitude of more than 30%; and the blades see localized loading varying by a factor of up to 2 during their rotation and changes in the amplitude of loads applied at the same location varying by more than 13%.