Aerodynamic modeling and wake characterization of a 15-MW offshore wind turbine: Insights from blade-resolved URANS simulations

As offshore wind turbines continue to scale up beyond 15 MW, their aerodynamic complexity and wake interactions present significant modeling and performance prediction challenges. This study investigates the aerodynamic behavior and wake characteristics of the IEA-15MW reference wind turbine using high-fidelity three-dimensional CFD simulations based on the URANS framework with the SST k − ω turbulence model. A series of blade-resolved simulations are conducted across a range of below-rated wind speeds to evaluate flow separation phenomena, spanwise force distribution, and local blade aerodynamics. The results reveal a nearly constant angle of attack (AOA) prior to pitch control engagement, with decreasing separation from root to mid-span and significant tip loss effects near the blade edge. A comparative analysis with Blade Element Momentum Theory (BEMT) demonstrates that BEMT overestimates the axial induction velocity and aerodynamic loading, which is attributed to an overprediction of the axial induction factor and limitations in the tip loss corrections. However, despite these differences in the force distribution along the blade, the results show comparable overall power estimates. Furthermore, the wake recovery process is governed by distinct mechanisms in the hub and tip regions: viscous and turbulent diffusion dominate recovery near the hub, whereas velocity shear primarily drives recovery in the tip region. In the far wake, the tip and hub vortices begin to interact and merge, enhancing the overall velocity recovery of the wake. Collectively, the findings provide critical insights into advanced aerodynamic modeling, accurate performance evaluation, and effective wake management strategies for next-generation ultra-large offshore wind turbines.