The project examined the dynamic aerodynamics of wind‑turbine rotor‑blade sections, with a particular focus on the onset and evolution of dynamic stall when the angle of attack changes rapidly. High‑fidelity computational fluid‑dynamics (CFD) simulations were carried out for a range of thick airfoils, notably the DU91‑W2‑250 and the Clark‑Y profiles. The numerical results were compared with experimental data; the lift (Cl) and drag (Cd) curves from the simulations matched the measured values closely, confirming the validity of the turbulence modelling and grid resolution used. Sensitivity studies on grid density and turbulence‑production parameters demonstrated that a mesh with at least 48 cells in the chordwise direction and a spanwise resolution of 24 cells provided converged results for the 2.5‑D simulations.

The core scientific contribution was the development of an improved dynamic‑stall model based on the ONERA framework. The original ONERA model, which uses a second‑order ordinary differential equation (ODE) to describe the evolution of the lift coefficient, was found to exhibit weaknesses in the dynamic load case, particularly in predicting the detachment of the leading‑edge vortex. To address this, the team introduced a robust detachment criterion, reformulated the model in local coordinates, and added a term to capture the influence of the dynamic‑stall vortex. The resulting equations for lift, drag, and moment include additional coefficients that depend on the change in lift (ΔCl) and the instantaneous angle‑of‑attack rate. These coefficients were calibrated against the CFD data, yielding a model that reproduces the transient lift overshoot and the subsequent recovery with high fidelity. The improved model remains a second‑order ODE system, making it computationally efficient for integration into load‑prediction tools.

Implementation of the refined model into an industrial load‑analysis framework was completed, allowing the model to be used in rapid aero‑elastic simulations. However, transferring the model into the open‑source FAST code maintained by the National Renewable Energy Laboratory (NREL) was not achieved within the project timeline because the required structural changes to FAST exceeded the scope of the current effort. The report therefore outlines a future collaboration with NREL to port the model into OpenFAST, which would enable its use in large‑scale wind‑turbine design studies.

Collaboration and funding details: the project was led by the Carl von Ossietzky University Oldenburg and was financed by the German Federal Environmental Foundation under reference 34736/01. The industrial partner Windnovation contributed to the development of the model and later transferred its work to a subcontract with Fraunhofer IWES after Windnovation’s withdrawal. The project ran from early 2022 until the final report in September 2024, covering the design, simulation, model development, and implementation phases. The outcomes include a validated dynamic‑stall model, a set of calibrated coefficients for thick airfoils, and a pathway for future integration into widely used wind‑turbine simulation tools.