Investigating wake reproduction of a model-scale wind turbine: experimental measurements versus Large Eddy Simulation with actuator line

Abstract. Accurate modeling of wind turbine wakes is essential for understanding turbine performance, wake interactions, and structural loading in wind energy applications. This work presents both numerical and experimental investigations aimed at evaluating the strengths and limitations of the Actuator Line Method (ALM) for wind turbine simulations in a controlled environment. Wind tunnel experiments were conducted using a purpose-built small-scale turbine TWIST (Turbine for Wind-tunnel Investigation & Scaled Testing) to provide high-resolution measurements of near wake velocity and blade deflection. In parallel, a numerical study was carried out using an ALM model developed with a force distribution designed to avoid averaging along the blade length in order to better capture variations in the near tip and hub regions. The inflow conditions in the simulations were carefully matched to the experimental profiles of mean velocity and turbulence intensity, ensuring that discrepancies would be mostly attributed to the modeling rather than to differences in inflow representation. Comparative analyzes between simulations and experiments were performed to assess the model’s ability to capture key near-wake features. Additionally, the influence of blade pitch angle on wake development was explored numerically. The blade deflection was analyzed both numerically and experimentally to evaluate the coupling between aerodynamic loading and structural response. The results show that the ALM, combined with distributing the hub drag over a Gaussian ellipsoid, is able to reproduce the main characteristics of the wake at 1.4 rotor diameter downstream, including the velocity deficit and the sharp transition between the wake and the free stream. Wake results at 4.35 diameter are also presented and are in line with the experiment, except very near the ground. Overall, the combined experimental and numerical approach provides valuable insight into the predictive capability of the ALM and its applicability for wind turbine modeling in controlled conditions.