An Experimental Investigation on the Performance and the Wake Characteristics of a Wind Turbine Subjected to Surge Motion

There are many advantages of floating wind turbines in deep waters, however, there are also significant technological challenges associated with it too. The dynamic excitation of wind and waves will induce excessive motions along each of the 6 degrees of freedom (6-DOF) of the floating platforms. These motions will then be transferred to the turbine, and directly impact the turbines’ performance and loadings. Advanced diagnostic technique methods were employed in order to elucidate the underlying physics of a wind turbine subjected to surge motion. In the absence of a combined wind-wave basin, and in order to replicate the dynamics of the surge motion of a floating offshore wind turbine (FOWT), a 1:300 scaled model wind turbine was installed on a high precision 3-DOF motion simulator device in a well-controlled, closed loop, dry-boundary layer wind tunnel. The inflow conditions of the wind tunnel were matched to that corresponding to the deep-water offshore environment. A Froude scaling method was employed in order to obtain the correct forces and responses on the floating turbine. In the case of the surge motion and in comparison with a traditional bottom-fixed turbine, the results of the wake study does show slight decrease in the entrainment of the turbulent kinetic energy from the high energy flow above the turbine. A slight increase in power output was also noted.