Aerodynamic enhancement and wake recovery of an asymmetric dual-rotor wind turbine: a coupled-dual rotor wake modelling and CFD investigation

This study proposes a novel asymmetric coaxial counter-rotating dual-rotor wind turbine (A-DRWT). Based on the asymmetric configuration of the A-DRWT, this study develops a Coupled-Dual Rotor (CDR) wake model by extending the Gaussian-distribution-based Jensen framework from a single-rotor representation to a coupled two-rotor formulation. The novelty of the model does not lie in introducing another Gaussian deficit function itself, but in separately resolving the wakes of the upwind rotor (UR) and downwind rotor (DR) and coupling them according to their asymmetric geometry and aerodynamic interaction. A dedicated correction is further introduced for the DR to account for the non-uniform inflow induced by the UR wake and the support struts. The model shows good agreement with the CFD results, with a maximum deviation of 5.39%, and indicates that the A-DRWT may allow a 30–40% reduction in downstream spacing compared with an equivalent SRWT. This work therefore provides a CFD-validated design concept and a low-order predictive framework for A-DRWT wake assessment. However, because wind-farm wake losses depend on the coupled effects of energy extraction, wake recovery rate and turbine spacing, further farm-scale assessment is required before drawing direct conclusions regarding net wind-farm energy gain or layout optimization.