Small wind turbine augmentation: Numerical investigations of shrouded- and twin-rotor wind turbines

The outcomes of research in increased-efficiency wind energy converters – twin-rotor- and shrouded wind turbines – are presented. The results of URANS simulations for various configurations of single- and twin-rotor, bare and shrouded machines are evaluated. A Fully-resolved Rotor Model with a sliding mesh approach was implemented into ANSYS CFX. A good correlation with the experimental data was shown. The model was used in a general study of the flow nature in the rotor plane, notably velocity fields. The distribution of aerodynamic forces on the blades, which permitted the aerodynamic force (lift and drag) coefficients to be determined in a reverse-BET procedure and to see how the shrouding modifies blade tip losses, was also analysed. •Research and comparison of open and shrouded, single and twin-rotor wind turbines.•URANS numerical evaluation of small wind turbine performance and flow features.•Analysis of velocity fields and angle of attack of various rotor configurations.•Discussion on aerofoil properties and behaviour using reverse Blade Element Theory.•Formulation and evaluation of a new tip loss correction for shrouded rotors.