A nonlinear decambering-corrected vortex lattice framework for multi-airfoil wind turbine blades: application to the NREL 5 MW rotor

Abstract

This paper presents a decambering-corrected nonlinear Vortex Lattice Method (NL-VLM) combined with a dedicated interpolation strategy for multiple airfoil sections, enabling accurate aerodynamic load predictions for utility-scale wind turbines at a low computational cost. This combined methodology constitutes the main contribution of the present work, integrating an iterative decambering correction within a rotating VLM framework together with a consistent multi-airfoil interpolation strategy, and extends the applicability of classical VLM formulations to nonlinear, stall-influenced operating regimes commonly encountered in large wind turbines. As wind turbines continue to increase in size and operational complexity, accurate yet computationally efficient aerodynamic models are required for design, analysis, and digital shadow applications. Although Computational Fluid Dynamics (CFD) provides high-fidelity predictions, its high computational cost limits its use in parametric analyses and coupled aeroelastic simulations, whereas VLM offers an efficient alternative but is traditionally restricted to linear, attached-flow conditions. To overcome these limitations, the proposed NL-VLM formulation accounts for viscous and stall effects, retaining the computational efficiency of VLM while significantly improving its predictive capability at high angles of attack, even with multiple airfoils along the blade span. The model is validated using the NREL 5 MW reference wind turbine, with aerodynamic power and thrust predictions compared against reference data from technical documentation and high-fidelity CFD results reported in the literature. Seven operating conditions are analyzed, yielding mean relative errors of approximately 9% for power and 18% for thrust, demonstrating that the proposed NL-VLM formulation provides reliable aerodynamic load estimates for large-scale wind turbines and represents a robust alternative for engineering and research applications.