An Experimental Investigation on the Aeromechanics and Near Wake Characteristics of Dual-Rotor Wind Turbines (DRWTs)

An experimental study was conducted to investigate the aeromechanic performance and near wake characterstics of dual-rotor wind turbine (DRWT) models with co-rotating or counter-rotating configurations in comparison to a conventional single rotor wind turbine (SRWT) model in order to elucidate the underlying physics to explore/optimize design of wind turbines for higher power yield and better durability. The experiments were performed in a large-scale Aerodynamic/Atmospheric Boundary Layer (AABL) wind tunnel under neutral stability conditions. In addition to measuring the power output performance of the SRWT and DRWT models, static and dynamic wind loads acting on the test models were also investigated. Furthermore, a high resolution PIV system was used for detailed near wake flow field measurements (free-run and phase-locked) to quantify the characteristics of the near wake flows and to reveal the transient behavior of the unsteady vortex structures in the wakes of SRWT and DRWT models. In the light of the promising experimental results on DRWTs, this study can be extended further to investigate the turbulent flow in the far wake of DRWTs and utilize multiple DRWTs in different wind farm operations.