Computationally efficient aerodynamic modeling of curved wind turbine blades and non-planar rotors using coupled near wake and vortex cylinder models

Abstract. Accurate aerodynamic modeling is essential for load calculation and optimization of modern wind turbine blades, which are increasingly flexible and may exhibit substantial sweep, prebend, coning, and deformation. Existing engineering models remain largely specialized to either sweep effects or prebend and non-planar effects, and therefore lack the ability to represent their combined influence within a single engineering formulation. This study develops a unified and computationally efficient framework for general curved and deformed blades by combining the coupled near and far wake model for swept blades with the vortex cylinder model for non-planar rotors. An idealized coupled formulation is first introduced as the highest-fidelity realization of the proposed framework before practical simplifications are introduced. Motivated by computational fluid dynamics (CFD) results showing that sweep and prebend effects can be modeled separately and then superimposed with good accuracy, simplified coupled models are then developed for practical applications. Comparisons with higher-fidelity free-wake lifting line (LL) and blade-resolved Reynolds-averaged Navier-Stokes (RANS) simulations show that the proposed models capture the aerodynamic load redistribution effects of curved blades with good accuracy across different blade configurations. In particular, for blades combining sweep and prebend, they close the gap between the previously separate sweep-only and prebend-only engineering approaches and provide clear improvements over existing specialized engineering models. The computational cost is higher than BEM but remains orders of magnitude lower than that of LL and CFD, making the simplified models attractive for time-domain aero-servo-elastic simulations and design optimization.