Aerodynamic characterization of stalled Darrieus turbine via experiment and low–order modelling

This study investigates the aerodynamic behaviour of a two-bladed, H-type Darrieus Wind Turbine (DWT) operating in stall-dominated regime via integrated experimental and numerical techniques. A time-resolved planar Par- ticle Image Velocimetry (PIV) approach provides the unsteady velocity fields around blade mid-span to reconstruct the corresponding angle of attack and rel- ative velocity enabling a hybrid derivation of sectional loads. A sensitivity assess- ment is performed to quantify the influence of the sampling strategy on flowfield reconstruction. In parallel, an engineering-fidelity Double-Multiple Streamtube (DMST) model is implemented and assessed against the present PIV data and selected literature. Comparative analysis between numerical predictions and ex- perimental observations are categorized by flow regime – identified from velocity, vorticity, and streamline-topology analyses — to assess model performance in at- tached, transitional, and separated flow conditions. This paper provides a workflow linking PIV to blade-resolved metrics for model vs experiment comparisons and a regime-aware validation of low-order numerical models, identifying conditions under which the quasi-steady assumptions are valid and when additional unsteady-physics modelling is required.