| 17 Aug 2026
Reduced-Order Modelling of Nonlinear Wind Turbine Blade Vibrations in a High-Fidelity Unsteady Aeroelastic Framework
Abstract. Accurate modelling of nonlinear wind turbine blade dynamics is essential for the reliable design and operation of modern wind turbines. Wind turbine blades have complex shapes with spatially varying sectional properties, twists and curvatures. The dynamics of long, flexible blades are strongly influenced by geometric nonlinearities, centrifugal effects, and material anisotropies. Conventional linear beam models are inadequate for capturing these complexities, since they are not designed to handle large deformations and nonlinear couplings. This study presents a high-fidelity nonlinear reduced-order model (ROM) for predicting the structural dynamics of modern wind turbine blades. The ROM uses a biorthogonal modal basis derived from the intrinsic mixed formulation of geometrically exact beam theory. The structural model is coupled to a high-fidelity unsteady vortex lattice solver in a two-way fluid-structure interaction framework, improving on the traditional blade element momentum method. The proposed model was validated using numerical and experimental results from the NREL 5-MW and SNL CX-100 wind turbine blades. Benchmark tests demonstrate that the ROM successfully captures the wind turbine blade’s nonlinear frequency response to harmonic loads and dynamic response to transient loads, including extreme wind gust, wind shear, and turbulence. Among the wind load cases tested, the ROM’s maximum out-of-plane tip displacement error was 0.77 % of reference tip deflection, compared with 20.90 % for conventional linear time-invariant models. This framework has applications in wind turbine control, structural health monitoring, fatigue life studies, and digital twins.
The manuscript is technically ambitious, but in its current form it's hard to follow. The principal contribution is obscured by the way the paper interweaves the IGEBT formulation, spectral finite-element discretization, full-order structural model, modal reduction, biorthogonal basis construction, SHARPy coupling, experimental validation, numerical benchmarking, and transient aeroelastic demonstrations.
The authors should establish a clearer hierarchy of models and evidence. In particular, the manuscript frequently blurs the distinction between validating the full-order structural model and validating the reduced-order model. The CX-100 experimental comparisons primarily validate the underlying structural formulation, whereas the NREL 5-MW ROM is benchmarked mainly against SHARPy. These are different levels of evidence and should not be described interchangeably.
The terminology also contributes to the confusion. The manuscript repeatedly refers to a “high-fidelity ROM,” although the high-fidelity elements are more properly the nonlinear beam formulation and the aeroelastic reference framework. The ROM is a reduced representation of that system. The paper should be more precise about which parts are full-order, which are reduced-order, which are used as reference solutions, and which are experimentally validated.
The paper would benefit from substantial restructuring around the actual scientific question: whether a biorthogonal modal reduction of IGEBT can reproduce the nonlinear structural response of a rotating wind-turbine blade with sufficient accuracy and computational advantage for aeroelastic applications. At present, this central thread is difficult to extract from the surrounding methodology.
I recommend that the authors reorganize the manuscript so that verification, validation, model reduction, and aeroelastic application are treated as clearly distinct stages. Without such restructuring, it is difficult to assess the significance of the reported results and the true level of validation of the proposed ROM.