The impact of platform motion phase differences on the power and load performance of tandem floating offshore wind turbines

The interactions between tandem floating offshore wind turbines remain an essential research topic with a view to optimizing future large-scale offshore wind farms. The focus of past floating offshore wind turbine aerodynamic research was centred on platform motion impact on rotor aerodynamics for standalone or in-phase tandem turbines. The question of how the differences in the surge motion phase of tandem turbines influence the performance of the downstream turbine remains open. Recent investigations reveal that these motions might not invariably be in-phase. This study seeks to determine the repercussions of platform motion phase differences on power, thrust, and wake recovery. Notably, it postulates that phase differences could detrimentally affect fatigue. Using a validated Navier–Stokes actuator line model rooted in the OpenFOAM® toolbox, the study aims to address this hypothesis. It was found that the out-of-plane root bending moment amplitude increase by 100% when the rotors are out of phase. A 72% increase in amplitude was also observed for CT. Both of these observations have also been linked to an increase in angle of attack amplitude over the blade span. This work stimulates future research in floating offshore turbine control strategies and provides guidance to minimize turbine failures and downtime.